SLIDES Intro Embedded Linux 3day Color

Introduction to Embedded Linux

Student Guide

Revision 2.00 April 2013

Technical Training Organization

Important Notice

ii Introduction to Embedded Linux

Important Notice Texas Instruments and its subsidiaries (TI) reserve the right to make changes to their products or to discontinue any product or service without notice, and advise customers to obtain the latest version of relevant information to verify, before placing orders, that information being relied on is current and complete. All products are sold subject to the terms and conditions of sale supplied at the time of order acknowledgment, including those pertaining to warranty, patent infringement, and limitation of liability.

TI warrants performance of its semiconductor products to the specifications applicable at the time of sale in accordance with TI’s standard warranty. Testing and other quality control techniques are utilized to the extent TI deems necessary to support this warranty. Specific testing of all parameters of each device is not necessarily performed, except those mandated by government requirements.

Customers are responsible for their applications using TI components.

In order to minimize risks associated with the customer’s applications, adequate design and operating safeguards must be provided by the customer to minimize inherent or procedural hazards.

TI assumes no liability for applications assistance or customer product design. TI does not warrant or represent that any license, either express or implied, is granted under any patent right, copyright, mask work right, or other intellectual property right of TI covering or relating to any combination, machine, or process in which such semiconductor products or services might be or are used. TI’s publication of information regarding any third party’s products or services does not constitute TI’s approval, warranty or endorsement thereof.

Copyright 2012 Texas Instruments Incorporated

Revision History August 2012 – Revision 1.0

Mailing Address Texas Instruments Training Technical Organization 6550 Chase Oaks Blvd Building 2 Plano, TX 75023

Introduction to Embedded Linux - Module 01: Booting Linux 01 - 1

Module 01: Booting Linux

Introduction This module begins by showing how a Linux distribution may be booted using a provided u-boot bootloader, Linux kernel and Linux filesystem. Next it shows how those same three elements may be rebuilt from source code and possibly reconfigured. Finally, the module covers some details of the “System five” (sys-V) initialization standard that is used to specify the startup configuration of many Linux distributions, including Arago (Beaglebone distribution) and Ubuntu (x86 Distribution.)

Module Topics

01 - 2 Introduction to Embedded Linux - Module 01: Booting Linux

Module Topics Module 01: Booting Linux .........................................................................................................................1-1

Module Topics ..........................................................................................................................................1-2

Booting Linux from Pre-Built Binaries ....................................................................................................1-4

Rebuilding and Modifying SDK Components ..........................................................................................1-9

System Startup Details ........................................................................................................................... 1-13

Lab 1 Introduction ................................................................................................................................. 1-17

Module Topics


Booting Linux from Pre-Built Binaries



Linux in Three Parts

Flash

BootloaderProvides rudimentary h/w initCalls Linux kernel and passes boot arguments

KernelInitializes the system (and device)Manages system resourcesProvides services for user programs

FilesystemSingle filesystem (/ root)Stores all system filesAfter init, kernel looks to filesystem for “what’s next”bootarg tells linux where to find root filesystem

File System

Linux Kernel

Boot Loader

Linux Boot Process

U-Boot

Linux Kernel

Init Process

Login Prompt

Power On

ARM assembly codePasses args to Linux (bootargs)

Initialize hardware via static drivers

/sbin/init – 1st process exe by kernel

Login consoleUsually one of first prog’s to run

Mount root filesys



Where Do You Find …

ROM bootloader supports NAND, NOR or SPI-flash boot (determined by BOOTM pins high/low at device powerup)Linux supports flash-based filesystems such as YAFFS and JFFSAll components may be flashed using U-boot (initial load via MMC or bootp) or JTAG using flashing utility via Code Composer Studio

Where located: Flash Boot

1a. SBL, UBL or MLO n/a1b. Bootloader (U-Boot) Flash

2. Linux Kernel Flash

3. Filesystem Flash


Multimedia Card (MMC) or Secure Digital card (SD) may be flashed using an MMC/SD programmer using a variety of utilitiesSimple, low cost method for booting Linux (or just U-boot) on a development board that has nothing pre-programmed (or for recovery.)

Where located: Flash Boot MMC Boot

1a. SBL, UBL or MLO n/a MMC1b. Bootloader (U-Boot) Flash MMC

2. Linux Kernel Flash MMC

3. Filesystem Flash MMC



Device

Booting Linux – MMC/SD Boot

RBL MLO U-Boot Kernel

ROM Internal RAM DDR2 DDR2

MMC/SD

DDR3MLO

UBoot Linux Kernel

RBLMLO

UBoot LinuxKernel

The ROM bootloader cannot make assumptions about external memory, so it can only load to the device’s internal memoryuBoot with MMC driver is too large to fit into internal memory

OCMC (on-chip memory controller)Internal memory


NFS boot is typically used for development but not production devicesAll components of the system are loaded from host server at each bootFilesystem changes on host are instantly reflectedUBL, U-boot and Linux Kernel changes are reflected on each rebootGood method to ensure uniformity across multiple development boards

Where located: Flash Boot MMC Boot NFS Boot

1a. SBL, UBL or MLO n/a MMC bootp / tftp1b. Bootloader (U-Boot) Flash MMC tftp

2. Linux Kernel Flash MMC tftp

3. Filesystem Flash MMC nfs



Step 1: Setup EZSDKSetup and Rebuild Linux EZSDKhost $ sudo apt-get update

host $ cd ti-sdk-am335x-evm-xx.xx.xx.xx

host $ sudo ./setup.sh

Installs tftp server, nfs server , minicom and packages needed to rebuild u-boot and kernel (using Aptitude package manager)Extracts AM335x Linux filesystem to specified location (default ${HOME}/targetfs), exports it via nfs server, and updates Rules.mak EXEC_DIR variableConfigures tftp server with specified read directory (default /tftpboot) and copies in prebuilt Linux kernel Configures minicom for TTYS0 serial device for 115,200 Baud, 8-bit, no parity, 1 stop bitCreates setup.minicom script to configure u-boot for desired boot type (mmc or tftp/nfs).

Step 2: Boot Linux from MMCMMC BootAttach SD/MMC programmer with inserted Micro-SD adapterhost $ cd ti-sdk-am335x-evm-xx.xx.xx.xx/bin

host $ sudo ./create-sdcard.sh

MLO (i.e. x-loader)u-boot.imguImage (i.e. Kernel)

RootFilesystem

Partition 1(FAT32)

Partition 2(EXT3)

ROM bootloader will load a file named “MLO” from partition 1, which must be FAT32 filesystemMLO (per MMC default config) boots a file named “u-boot.bin” from partition 1 of FAT32 MMC

Linux root filesystem must be in its own partition.



U-boot Default Scripting

Detect MMC? Attempt to load uEnv.txt

Boot from NAND

Attempt to run uenvcmd

Attempt boot from MMC

Other Boot Options (Macros in Default U-boot Environment)1. NOR Flash boot2. SPI Flash boot3. TFTP/NFS (network) boot

Linux Boot Arguments for MMC Bootmmc_load_uimage=

fatload mmc 0 0x80007fc0 uImage

uBoot will attempt to load Linux kernel binary with filename “uImage” from mmc/sd partition 0, which must be fat32 formatted.

Kernel image will be loaded into physical address 0x80007fc0, an offset into DDR3. Subsequent call of “bootm” will boot the kernel from DDR3.bootargs=

console=ttyO0,115200n8 bootdelay=3 root=/dev/mmcblk0p2 rw rootfstype=ext3 rootwaitip=none

Linux boot arguments set up a serial console for login and specify the root filesystem location as mmc/sd device 0 partition 2, which must be ext3 formatted.

“ip=none” allows boot scripts in filesystem to define ip settings (/etc/network/interfaces).

bootdelay and rootwait provide delays for mmc.

Rebuilding and Modifying SDK Components



Rebuilding EZSDK

Rebuild SDKhost $ make help

host $ make clean

host $ make all

Install rebuilt components to export directory (default ${HOME}/targetfs)host $ make install

make all rebuilds:U-bootLinux KernelOpenGL graphics Demos

Example ApplicationsWireless Driver Support

Device

Booting Linux – MMC/SD Boot

RBL MLO (x-loader) U-Boot Kernel


MMC/SD

DDR3

MLO(x-loader)

UBoot Linux Kernel

RBLMLO

(x-loader)

UBoot LinuxKernel

The ROM bootloader cannot make assumptions about external memory, so it can only load to the device’s internal memoryuBoot with MMC driver is too large to fit into internal memory

OCMC (on-chip memory controller)Internal memory



MLO (U-boot_min) Build

host $ cd ti-sdk-am335x-evm-xxx/board_support/u-boot-xxx

host $ make distcleanhost $ make ARCH=arm CROSS_COMPILE=arm-arago-linux-gnueabi- am335x_evm_config*

host $ make ARCH=arm CROSS_COMPILE=arm-arago-linux-gnueabi- MLO

MLO (x-loader) U-Boot Kernel


RBL

* For available configs: host$ ls include/configs

U-Boot Build


host $ make distcleanhost $ make ARCH=arm CROSS_COMPILE=arm-arago-linux-gnueabi- am335x_evm_config

host $ make ARCH=arm CROSS_COMPILE=arm-arago-linux-gnueabi- u-boot.img



Both MLO and u-boot.img may be built simultaneously using host $ cd ti-sdk-am335x-evm-xxx/board_support/u-boot-xxx

host $ make distcleanhost $ make ARCH=arm CROSS_COMPILE=arm-arago-linux-gnueabi- am335x_evm

RBL



Kernel Build

host$ cd ti-sdk-am35x-evm_xxx/board_support/linux-xxx-psp-xxx

host$ make mrproper

host$ make ARCH=arm* am335x_evm_defconfig**

host$ make ARCH=arm menuconfig

host$ make ARCH=arm CROSS_COMPILE=arm-arago-linux-gnueabi- uImage

host$ make ARCH=arm CROSS_COMPILE=arm-arago-linux-gnueabi- modules

host$ make INSTALL_MOD_PATH=${HOME}/targetfs modules_install



* For available ARCH: host$ ls arch/** For available configs: host$ ls arch/arm/configs

RBL

“make menuconfig” options



Kernel Object Modules

# insmod <mod_name>.ko [mod_properties]

Use insmod (short for insert module) command to dynamically add modules into the kernelKeep statically built kernel small (to reduce size or boot-up time), then add functionality later with insmodInsmod is also handy when developing kernel modules

Linux Kernel source code is broken into individual modulesOnly those parts of the kernel that are needed are built in

Kernel Module Examples:fbdev frame buffer devv4l2 video for linux 2nfsd network file server devdsp oss digital sound proc.audio alsa audio driver

1. Static(built-in)

2. Dynamic(insmod)

.ko = kernel object

Linux Kernel

v4l2

fbdev

dsp

oss

nfsd ext3

httpd

System Startup Details



File System

Linux Kernel

Boot Loader

Linux Boot Process

U-Boot

Linux Kernel

Init Process

Login Prompt

Power On

ARM assembly codePasses args to Linux (bootargs)

Initialize hardware via static drivers

/sbin/init – 1st process exe by kernel

Login consoleUsually one of first prog’s to run

Mount root filesys

Linux Initialization ProcessThe initialization process is launched by the Linux Kernel after the root filesystem is mountedBy default it is located at /sbin/init, but it can be specified as a kernel boot argument

/etc/inittab /etc/init.d

/etc/rcX.d

bootmisc.sh syslog

mountnfs.sh telnetd

networking thttpd

S05networking S20syslog

S10telnetd S20thttpd

S20syslog S60mountnfs

/sbin/init



SysV Startup

Arago and most Linux distributions use the SysV(“System Five”) startup process/etc/init.d directory holds all scripts used for boot-up/etc/rcX.d (i.e. /etc/rc5.d) contains links to these scripts specifying which should run and in what order for a given run level 1-5 (5 is default)Sxx precedes the name of each link in rcX.d. “S” indicates it is run at startup, “xx” indicates the order

/etc/init.d

/etc/rcX.d

bootmisc.sh syslog

mountnfs.sh ...


S10telnetd ...

Beaglebone Arago Runlevel 5 Startup

S01psplash S10checkroot S37populate-volatile.sh S45mountnfs.shS02banner S12udev-cache S38devpts.sh S55bootmisc.shS03sysfs S20modutils.sh S39alsa-state S99finish.shS03udev S30ramdisk S40configureS06alignment S35mountall.sh S41networking

/etc/rcS.d

Sxx scripts are executed when entering a runlevel, according to the order of “xx” (01 first)Kxx scripts are executed when exiting a runlevel, according to reverse order of “xx” (99 first)

S10dropbear S20syslog S70lighttpd S98storage-gadget-initS10telnetd S20thttpd S97matrix-gui-2.0 S99gplv3-noticeS20netperf S30pvr-init S98parse-ip S99rmnologin

/etc/rc5.d



/etc/inittab# The default runlevel.id:5:initdefault:# Boot-time system configuration/initialization script.# This is run first except when booting in emergency (-b) mode.si::sysinit:/etc/init.d/rcS# Run-level configuration/initialziation scriptsl0:0:wait:/etc/init.d/rc 0l1:1:wait:/etc/init.d/rc 1l2:2:wait:/etc/init.d/rc 2l3:3:wait:/etc/init.d/rc 3l4:4:wait:/etc/init.d/rc 4l5:5:wait:/etc/init.d/rc 5# Other InitializationsS:2345:respawn:/sbin/getty 115200 ttyO0

Format:<id>:<runlevels>:<action>:<process>

/etc/fstab

# stock fstab - you probably want to override this with a machine specific one

rootfs / auto defaults 1 1proc /proc proc defaults 0 0devpts /dev/pts devpts mode=0620,gid=5 0 0usbfs /proc/bus/usb usbfs defaults 0 0tmpfs /var/volatile tmpfs defaults,size=16M 0 0tmpfs /dev/shm tmpfs mode=0777 0 0tmpfs /media/ram tmpfs defaults,size=16M 0 0

# uncomment this if your device has a SD/MMC/Transflash slot#/dev/mmcblk0p1 /media/card auto defaults,sync,noauto 0 0

Format:<device>:<mount point>:<filesys type>:<options>:<backup>:<check>



inetd/xinetduser@ubuntu:~$ ls /etc/xinetd.dchargen daytime discard echo tftp time

service tftp{protocol = udpport = 69socket_type = dgramwait = yesuser = nobodyserver = /usr/sbin/in.tftpdserver_args = /tftpbootdisable = no}

• Beaglebone Arago distribution does not use xinetd• Many desktop distributions do, including Ubuntu• Ubuntu launches xinetd from /etc/rc5.d/S20xinetd

xinetd is a replacement for inetd, the internet services daemon. It listens for requests and forwards to appropriate service according to port number.

/sbin/init vs distribution

/etc/inittab

/sbin/init

/etc/init.d

/etc/rcX.d

bootmisc.sh syslog

mountnfs.sh ...


S10telnetd ...

/etc/fstab

Ultimately, the meaning of initialization scripts are driven completely by /sbin/initInitialization scripts and tables only have meaning for a given distribution if recognized by /sbin/init

Beaglebone Arago

Lab 1 Introduction


Lab 1 Introduction

Lab 1: Booting Linux

A. Start and Configure Ubuntu VmwareB. Create Bootable SD CardC. Boot Linux on Beaglebone

Vmware:Software emulated “Computer within a computer.”

Allows us to run Ubuntu Linux on a Windows machine

Ubuntu:Very popular desktop distribution of Linux

Completely Free



MLO (i.e. x-loader)u-boot.imguImage (i.e. Kernel)

RootFilesystem

Partition 1(FAT32)

Partition 2(EXT3)

1. Use mkcard.txt script to format and partition card

2. Mount micro-SD partitions into root filesystem(Discussed in Module 5)

3. Copy MLO, u-boot and uImage into partition 1

4. De-archive filesystem into partition 2

Lab 1 Introduction




1. Map Serial-over-USB and Ethernet-over-USB to VM

2. Launch minicom serial terminal emulator

3. Manually load Ethernet-over-USB driver.

Introduction to Embedded Linux - Module 02: Linux Distributions 02 - 1

Module 02: Linux Distributions

Introduction A Linux distribution is the entire collection of software necessary to run Linux on a given platform. At the minimum, this is a bootloader, a Linux kernel and a Linux filesystem. Additionally, some distributions incorporate various tooling for configuring or debugging the distribution.

This module will discuss distributions genericly, then focus on the Arago distribution, which is the distribution that is tested and maintained by Texas Instruments for use on TI platforms.

Module Topics

02 - 2 Introduction to Embedded Linux - Module 02: Linux Distributions

Module Topics Module 02: Linux Distributions ................................................................................................................2-1

Module Topics ..........................................................................................................................................2-2

(Short) Product Overview ........................................................................................................................2-3

Linux Distributions ..................................................................................................................................2-7

MMU and Dynamic Libraries ................................................................................................................ 2-15

Lab 2: Terminal Manipulation ............................................................................................................... 2-19

(Short) Product Overview



TI Embedded Processors Portfolio

32-bitReal-time

32-bit ARM

ARMIndustry StdLow Power

<100 MHz

Flash64 KB to 1 MB

USB, ENET, ADC, PWM, SPI

Host Control

$2.00 to $8.00

16-bit

Microcontrollers

MSP430Ultra-Low

Power

Up to 25 MHz

Flash1 KB to 256 KB

Analog I/O, ADCLCD, USB, RF

Measurement,Sensing, General

Purpose

$0.49 to $9.00

DSP

C647x, C64x+, C674x, C55x

Leadership DSP Performance

24,000 MMACS

Up to 3 MBL2 Cache

1G EMAC, SRIO,DDR2, PCI-66

Comm, WiMAX, Industrial/

Medical Imaging

$4.00 to $99.00+

ARM+

ARM9Cortex A-8

Industry-Std Core,High-Perf GPP

Accelerators

MMU

USB, LCD,MMC, EMAC

Linux/WinCE User Apps

$8.00 to $35.00

DSP

C64x+ plusARM9/Cortex A-8Industry-Std Core +DSP for Signal Proc.

4800 MMACs/1.07 DMIPS/MHz

MMU, Cache

VPSS, USB, EMAC, MMC

Linux/Win +Video, Imaging,

Multimedia

$12.00 to $65.00

ARM + DSP

ARM-Based

C2000™Fixed &

Floating Point

Up to 300 MHz

Flash32 KB to 512 KB

PWM, ADC, CAN, SPI, I2C

Motor Control, Digital Power,

Lighting, Sensing

$1.50 to $20.00

ARM CPU Processor Cores

http://www.arm.com/products/processors/index.php

ARM11

ClassicARM Processors

ARM7Cortex-M3

Cortex-M4

Cortex-R4

Cortex-A8

EmbeddedCortex Processors

ApplicationCortex Processors

ARM9

Capability

Per

form

ance

, Fun

ctio

nalit

y

TI’s ARM core's supporting Linux...



TI ARM® investment and innovation

* TI licensed in July 2003, but publicly announced Oct 2005.

Newest DaVinci solution for

flexible, HD video

Two ARM Cortex-R4

cores for

automotive

TI Licenses

first ARM core

1995

1st single-chip digital baseband -

DSP/ARM multi-core

1st multi-core applications processor,

ARM9-based

2002 2005

*TI first licensee for ARM Cortex™- A8

Introduced DaVinci™ processors for

digital video – ARM9™-based SoCs

2006

1st ARM Cortex-A8

based silicon

2007

TI Licenses

ARM Cortex-A9

2009

TI Acquires Luminary

Micro

TI announces

31 new Stellaris®

andARM-based

MPUs

Stellaris®

Sandstorm Class

Stellaris®

Fury Class

2008

Stellaris®

DustDevil Class

Stellaris®

Tempest Class

StellarisMCUFixed/

Floating-Point ARM9 SoC

1993

TMS570FMCU

1st R4F-based floating-point, dual-core auto

MCU

DaVinci™

OMAP™

OMAP 3

OMAP™

OMAP1510

DaVinci™ TMS570MCU

OMAP™

OMAP-L138

2010 2011

Lead Licensee

on Cortex-

M4

Introduce ARM Cortex-A9

based siliconOMAP™

OMAP 4

Introduce ARM

Cortex-A15

based siliconOMAP™

OMAP 5

TI Licenses Cortex-A15

TI has shipped over 6 billion ARM-based products and continues to invest in a large portfolio of scalable platforms from $1 to >1GHz

TI Licenses Cortex-A7

AM335x Cortex™-A8 based processorsBenefits• High performance Cortex-A8 at ARM9/11 prices• Rich peripheral integration reduces complexity and cost

Sample Applications

Software and development tools• Linux, Android, WinCE and drivers direct from TI• StarterWare enables quick and simple programming of and

migration among TI embedded processors • RTOS (QNX, Wind River, Mentor, etc) from partners• Full featured and low cost development board options

Power Estimates• Total Power: 600mW-1000mW• Standby Power: ~25mW• Deep Sleep Power: ~5-7mW

Schedule and packaging• Samples: October 31, 2011; Production: 2Q’12• Dev. Tools: Order open October 31, 2011• Prelim docs: available today• Packaging: 13x13, 0.65mm via channel array

15x15, 0.8mm

• Home automation• Home networking• Gaming peripherals• Consumer medical appliances• Printers• Building automation• Smart toll systems

• Weighing scales• Educational consoles• Advanced toys• Customer premise equipment• Connected vending machines

Availability of some features, derivatives, or packages may be delayed from initial silicon availability Peripheral limitations may apply among different packagesSome features may require third party supportAll speeds shown are for commercial temperature range only * 720 MHz only available on 15x15 package. 13x13 is planned for 500 MHz.

** Use of TSC will limit available ADC channels. SED: single error detection/parity

ARM®

Cortex-A8up to

720* MHz

L3/L4 Interconnect

Serial Interface

32K/32K L1 w/SED

256K L2 w/ECC

64K RAM64K

SharedRAM

Display24 bit LCD Ctrl (WXGA)

Touch Scr. Ctrl.**

Securityw/ crypto acc.

PRU SSPRU x2200 MHz

12K RAMw/SED

Peripherals8K P. w/SED8K D. w/SED

System

Memory InterfaceLPDDR1/DDR2/DDR3

NAND/NOR(16b ECC)

ParallelEDMA

Timers x8WDTRTC

eHRPWM x3eQEP x3eCAP x3

JTAG/ETBADC (8ch)

12-bit SAR**

UART x6SPI x2I2C x3

McASP x2(4ch)

CAN x2(2.0B)

MMC/SD/SDIO x3

GPIO

USB 2.0 OTG+ PHY x2

EMAC 2port10/100/1Gw/1588 &

switch (MII,RMII, RGMII)

GraphicsPowerVR

SGX 3D Gfx



Demos

Kit Contents

Documentation

• User and Demo guide, Releases: TI Wireless Connectivity Wiki• Module WL1271-Type TN Datasheet from Murata

COM6M WL1271 Adapter Boardis included in AM335x EVM Kit

AM335x/WL1271 Development Kit

Software

AM335x EVMavailable for purchase throughTI E-store: TMDXEVM3358

• QT based WLAN and Bluetooth® demoApplications integrated into SDK

• WPA Supplicant and HostApd GUIs for WiFi Station and Soft APsetup

• Profusion Bluetooh GUI with BMG (Scan, Pair, Connect), A2DP, FTP, OPP and SPPdemos

• TI AM335x EVM Kit includes AM3358 Microprocessor, 512 MB DDR2, TPS65910 Power management IC, 7” LCD, Software & Tools, WL1271 COM6M Adapter Card

• Open Source Linux 3.2 drivers• Pre-Integrated with TI Linux SDK• mac80211 Open Source WLAN Driver• BlueZ Open Source Bluetooth® stack• BlueZ OpenObex Profiles

WL1271-TypeTN (Murata)WLAN 802.11 b/g/n and Bluetooth® v4.0 BLE Module

Features• IEEE 802.11 b/g/n compliant• Bluetooth 4.0 with Bluetooth Low Energy• Wi-Fi Direct• TI’s proven 6th generation Wi-Fi and

Bluetooth solution• Pre-integration with high performance

Cortex-A8 based AM335x processor platform• Open-source compliant Wi-Fi and Bluetooth

drivers• FCC Certified, ETSI & EMC Tested WL1271

module• Sample applications and demos

Applications• Mobile consumer devices• Industrial and home automation, metering• Portable data terminals• Video conferencing, video camera

Benefits• Seamless, direct and high throughput Wi-Fi

connectivity between devices (no external access points needed)

• High throughput, reliable signal integrity, best in class coexistence, enhanced low power

• Simplified and reduced hardware and software integration effort, get started quickly

• Platform enables high performance processing and increased level of integration at value-line pricing

• Open-source compliant Wi-Fi and Bluetooth drivers• Certified modules lowers manufacturing and

operating costs, saves board space and minimizes RF expertise required

www.ti.com/wl1271typetn

LBEE5ZSTNC-523



What is Pin Multiplexing?

How many pins is on your device?How many pins would all your peripheral require?Pin Multiplexing is the answer – only so many peripherals can be used at the same time … in other words, to reduce costs, peripherals must share available pins Which ones can you use simultaneously?

Designers examine app use cases when deciding best muxing layoutRead datasheet for final authority on how pins are muxedGraphical utility can assist with figuring out pin-muxing… Pin mux utility...

HPIuPP

Pin Mux Example

Pin Muxing Tools

Graphical Utilities For Determining which Peripherals can be Used SimultaneouslyProvides Pin Mux Register Configurationshttp://wiki.davincidsp.com/index.php?title=Pinmux_Utilities_for_Davinci_Processors

Linux Distributions


Linux Distributions

What Is a ‘Linux Distribution’A ‘Linux distribution’ is a combination of the components requiredto provide a working Linux environment for a particular platform:1. Linux kernel port

A TI LSP or Linux PSP is a Linux kernel port to a device, not just a set of device drivers

2. BootloaderUboot is the standard bootloader for ARM Linux

3. Linux ‘file system’This does NOT mean a specific type of file system like FAT file system or flash file system … rather, it more like the “C:\” drive in WindowsIt refers to all the ‘user mode’ software that an application needs such as graphics libraries, network applications, C run-time library (glibc, uclibc), codec engine, dynamically-loaded kernel modules (CMEM, DSPLINK)

4. Development toolsCodeSourcery - GCC, GDBMV DevRocket, CCSv5 (beta), GHS Multi, etc.

O/S Choices

Choices

Linux Android(arowboat.org) WinCE

Commercial Community

Others …

• QNX• Nucleus• BIOS• Etc.

Build ItYourself

Linux Distributions


O/S Choices

Choices



Others …


Build ItYourself

LinuxMontaVistaTimeSysWind RiverMentorRidgerun

WinCEAdeneoMistralMPC DataBSQUARE

Commercial O/S Vendors

Linux Partner StrategyCommercial: provide support, off-the-shelf Linux distributions or GNU toolsConsultants: provide training, general embedded Linux development expertise, or specific expertise for developing drivers or particular embedded applicationshttp://www.tiexpressdsp.com/index.php/Linux_Consultants_and_Commercial_Linux_Providers

RTOSGreen HillsWind River (VxWorks)ELogic (ThreadX)QNXMentor (Nucleus)

Linux Distributions


O/S Choices

Choices



Others …


Build ItYourself

Arago Lineage

Open Embedded

Angstrom

Arago

ubootsource

Various GNU appskernel.org

Many DistributionsMany Platforms

One DistributionMany Platforms

One DistributionTI Platforms

Linux Distributions


Arago Feedback Loop

Open Embedded

Angstrom

Arago

ubootsource

Various GNU appskernel.org

TI-specific drivers and patches pushed back to community

O/S Choices

Choices



Others …


Build ItYourself

Linux Distributions


Open EmbeddedOpen Embedded is a Linux open-source project to provide a build system for building and maintaining a Linux DistributionThe Open Embedded project contains contributions from many different Distribution maintainers (such as Angstrom and Arago)Most OE Distributions are aimed at Embedded Applications (but this is not a requirement.)Open Embedded uses a build system called “Bitbake” which builds a distribution from “recipe” files.OE Users may build community distributions from provided recipes or modify existing recipes to create a custom distribution.

Bitbake Recipe FileaDESCRIPTION = "nodeJS Evented I/O for V8 JavaScript“

HOMEPAGE = "http://nodejs.org"

LICENSE = "MIT"

DEPENDS = "openssl"

SRC_URI = " http://nodejs.org/dist/node-v${PV}.tar.gz

file://libev-cross-cc.patch

file://node-cross-cc.patch "

SRC_URI[md5sum] = "c6051dd216817bf0f95bea80c42cf262 "

S = "${WORKDIR}/node-v${PV}"

do_configure () {

./configure --prefix=${prefix} --without-snapshot }

do_compile () { make }

do_install () { DESTDIR=${D} oe_runmake install }

Includes download instructions, build instructions and dependencies

http://www.openembedded.org/wiki/How_to_create_a_bitbake_recipe_for_dummies

Linux Distributions


Arago Project Downloads

Arago install and updates are distributed via gitArago install includes Bitbake, Open Embedded recipesA separate page contains pre-built binaries (snapshots)

Ångström : Narcissus

(http://www.angstrom-distribution.org/narcissus)

Linux Distributions


Using opkg to Add New Packages

To see the commands the opkg package manager supportshost$ opkg

To install an opkg-compliant packagehost$ opkg install <packagename>.ipkg

To download a package but not install ithost$ opkg download <packagename>

To find out which packages provides a given filehost$ opkg whatprovides <filename>

To list which packages are availablehost$ opkg list

To update the list of available packages and “whatprovides” searchhost$ opkg update

Using opkg to Trim Down a Filesystem

You can start by listing all packages that are installed on the systemhost$ opkg list-installed

If you find a package you don’t think you need, good idea to check what other packages depend on it before removing

host$ opkg whatdepends <packagename>

Assuming you don’t need any of the packages that depend on this one, you can remove it and all dependent packages

host$ opkg remove <packagename> \--force-removal-of-dependent-packages

If you suspect a file is part of a package you don’t need, you can determine the package that installed it using

host$ opkg search <file>

Linux Distributions


Linux Distributions Options for TI

Ease of UseEasyTested

Experienced User Latest

Commercial Community Custom(Build it Yourself)

TimesysMontaVistaEtc.

TI SDK(PSP)

Ångström / Arago

Open Embedded

(OE)

Custom from

Sources

Binary(Update patches)

BinaryUpdated foreach SDKrelease

BinaryNarcissus(online tool)opkg

Bit-BakeRecipies

“GIT”from kernel.org, and others

MMU and Dynamic Libraries



FragmentationProblem:Over time, the system heap that is used to manage dynamic memory becomes fragmented.

Free Memory

Allocated Memory

FreeAllocated

Free

Allocated

FreeAllocated

Free

Allocated

mallocfreemallocfree…

Virtual MemorySolution:A Memory Management Unit (MMU) maps fragmented physical memory into “virtually contiguous” memory

FreeAllocated

Free

Allocated

FreeAllocated

Free

Allocated

Allocated Memory

Free Memory

MMU



Memory ProtectionThe memory management unit also provides memory protection by denying access to regions of physical memory that are not allocated to a given application

Application 1 Memory

(unused)


(unused)

Application 1

Application 2

Physical Memory

MMU

Memory ProtectionWhen application 1 is executing, it’s application memory is mapped to a valid virtual address. Disallowed memory is assigned no virtual address and is therefore unreachable.


(unused)


(unused)

Application 1Physical Memory

MMU

Allowed



MMU Details

All user-mode applications access memory via the MMUKernel and drivers bypass the MMU and access memory via physical addresses.In desktop systems (not commonly in embedded), virtual memory is used to extend ram by virtualizing storage media such as a hard disk (swap space/demand paging.)

Static Linking and .a Libraries (Archives)

Application 1

MMU

Application 2

Common libraries are shared across applications and dynamically linked


(unused)


(unused)

Physical Memory

Static Libs

Static Libs



Dynamic Linking and .so Libraries

Physical Memory

Application 1Application 1 Memory(unused)

Shared Libraries

(unused)


(unused)

MMU

Application 2

Common libraries are shared across applications and dynamically linked

Linking Linux Libraries

# gcc myfile.c –lm -lpthread

This links the dynamic libraries:libm.so – shared math librarylibpthread.so – shared POSIX thread library

or the static libraries (archives)libm.a – staic math librarylibpthread.a – static POSIX thread library

Depending on which library appears first in the library search path.

Lab 2: Terminal Manipulation



Lab 2 – Beginner and Advanced Tracks

Beginner(beginner) Basic Terminal Manipulation(beginner) Basic File Manipulation

Advanced(advanced) Linux Redirection(advanced) Linux Scripting

You may not have time to complete both tracks, so choose wisely!

Should I take the Beginner Track?

Commands Covered:cat cd cp pwd ls mkdir

mv rm rmdir touch

Concepts Covered:wildcard (*) home directory (~)autofill (<tab>) terminal history (arrow keys)text editor (gedit)



(Page intentionally left blank)

Introduction to Embedded Linux - Module 03: The git Tool 03 - 1

Module 03: The git Tool

Introduction The git tool is an open-source software package used for managing different versions of software. git is used throughout the Linux community, and is the version management tool used by the developers of the Linux kernel itself. Furthermore, Arago, the free, open-source distribution that is tested and maintained by Texas Instruments, uses git as its versioning software.

By learning the git tool, you will be able to apply updates and patches from the Arago distribution with far less effort than would be required to do the same task manually. Furthermore, git has a plugin to Code Composer studio that will be discussed in the next chapter. This plugin allows you to use git to seamlessly manage any CCS project.

Module Topics

03 - 2 Introduction to Embedded Linux - Module 03: The git Tool

Module Topics Module 03: The git Tool .............................................................................................................................3-1

Module Topics ..........................................................................................................................................3-2

git Overview .............................................................................................................................................3-3

Adding Commits .......................................................................................................................................3-5

Adding and Merging Branches .............................................................................................................. 3-11

Lab 3: Using git ..................................................................................................................................... 3-16

git Overview


git Overview

git Branches

Creating a new git repositoryYou may create a new git repositoryhost$ mkdir ~/git/my_project

host$ cd ~/git/myproject

host$ git init

host$ cp ~/project_files/* ~/myproject

host$ git add *

host$ git commit –m “initial_version”

Step 1: make a directory to hold your project filesStep 2: use “git init” to initialize the directory with git metadataStep 3: add files to the projectStep 4: use “git add” to add files from the directory to the git repository

(just placing the file in the git directory hasn’t added them to get yet!)Step 5: use “git commit” to commit the current state of the git repository,

with the reference tag “initial_version”

git Overview


Cloning an Existing git Repository

By cloning a public repository, you create a local copy that can be accessed without internet connectivity.host$ mkdir ~/git

host$ cd ~/git

host$ git clone git://git.kernel.org/pub/scm/git/git.git

Cloning is better than simply copying source files because1. Automatically creates a local git repository2. Allows you to pull external changes (patches) from the

public repository and merge them into your copy3. Depending on configuration, allows you to push your

changes back to the public repository

git Commit and Branches

branch 2

commit

commit

commit

commit

commit

commit

commitbranch 3

• Branch 1 is by default named “master”• Branch 2 is derived from master, branch 3 is derived from a branch 2 commit• Each commit is a diff (difference operation) from the previous commit

master(branch 1)

commit

Adding Commits


Adding Commits

Creating a Repository

host$ mkdir ~/my_project

host$ git init

host$ cp ~/project_files/* ~/myproject

host$ git add *

host$ git commit –m “initial_version”

HEAD

The HEAD marker indicates your position within the branch/commit structure.By default git names the first branch “master,” although this can be overridden.

master(branch 1)

Making Commits

commit

(make changes to “file1” and “file2”…)

host$ git add file1

host$ git commit

Only files that have been “git add”-ed since last commit will be committed, regardless of which files have been changed.As a shortcut, you can commit all files that have been previously added to the index with “git add” using:host$ git commit -a

HEAD

master(branch 1)

Adding Commits


Making Commits

commit

(make changes to “file1” and “file2”…)

host$ git add file1

host$ git commit

host$ git add file2

host$ git commit

commitHEAD

master(branch 1)

Commits and SHA1 sums

Each time a commit is made, an SHA1 hash operation is used to assign the commit a unique identifier.

host$ git log

commit b87bd642de3c1d6a47cde7bfa9305a29606c7781

Author: user <[email protected]>

Date: Wed Aug 1 11:49:53 2012 -0700

initial commit

A commit can be retrieved using the checkout command with its SHA1 sum

host$ git checkout b87bd642de3c1d6a47cde7bfa9305a29606c7781

Adding Commits


git tags

Checking out commits by their SHA1 sum is tedious and the SHA1 sum is not particularly informative. Instead, one may create a tag to reference the commit

host$ git tag –a myTag –m “message” b87bd642de3c1d6a47cde7bfa9305a29606c7781

This tag is now an alias for the commit’s SHA1 sum

host$ git checkout myTag

Tracked and Staged Filesfile1

file2

Index Staging Area

host$ touch file1 file2

host$

New files in a git repository are not tracked until added

git repository

Adding Commits



file2

file1

file2

file1

file2

Index Staging Area


host$ git add *

“git add” moves files to Staging Area and adds them to index

git repository


file2

file1

file2

Index Staging Area


host$ git add *

host$ git commit

“git commit” clears the staging area

git repository

Adding Commits



file2

file1

file2

file2

Index Staging Area


host$ git add *

host$ git commit

host$ git add file2

host$ git commit

Only files in Staging Area are committed by “git commit”

git repository


file2

file3

file1

file2

(file1)

(file2)

Index Staging Area


host$ git add *

host$ git commit

host$ git add file2

host$ git commit

host$ touch file3

host$ git commit -a

“git commit -a” commits all files in the index (not repository)

git repository

Adding Commits


git statusfile1

file2

file3

file1

file2

file2

Index Staging Area

host$ git status

# On branch master

# Changes to be committed

# modified: file2

# Changes not staged for commit:

# modified: file1

# Untracked files:

# file3

“git status” reports status of index and staging area

git repository

Adding and Merging Branches



Making a New Branch

host$ git branch branch2

Creating a branch does not change your current position (i.e. currently checked-out commit)

branch 2

commit

commitHEAD

master(branch 1)

Making a New Branch


(change file1)

host$ git commit -a

commit

commit

commit branch 2HEAD

master(branch 1)



Making a New Branch


(change file1)

host$ git commit -a

host$ git checkout branch2

Use “git checkout” to move to new branch

branch 2

commit

commit

master(branch 1)

HEADcommit

Making a New Branch (Example 2)

host$ git branch branch2(change file1)host$ git commit -ahost$ git checkout branch2(create file2)host$ git add file2host$ git commit -a

branch 2

commit

commit

commit HEAD

master(branch 1)

commit



Merging git Branches

branch 2

commit

commit

commit

HEAD

master(branch 1)

commit

commithost$ git checkout branch2host$ git merge masterhost$ git commit -a

U-boot Practical Example

commit

U-bootmaster

1. Ima Pro of Penguins, Inc. clones the Arago u-boot for AM335x EVM from arago-project.org




commit


2. Ima ports U-boot to the Penguins, Inc. production board

penguin

commit

U-bootmaster



2. Ima ports U-boot to the Penguins, Inc. production board3. As U-boot is updated on Arago git, Ima merges patches

commit

commit

commit

penguin

commit

U-bootmaster




commit penguin

commit

U-bootmaster

commit

commit

commit

commit

penguinpro 2e

commit

commit

commitcommit4. Ima gets promoted5. Ima takes up golf6. Ima retires in Tahiti

Lab 3: Using git


Lab 3: Using git

Lab 3: Exploring git

A. Exploring git’s own git repositoryB. Create a new git repository

A. Use “git branch,” “git tag” and “git log” to get the “lay of the land” from a real-world git repository and then use “git checkout” to rebuild a specific version

B. Use “git init” to create a new repository and then “git commit” and “git tag” to save files in various states and explore the effects of “git checkout” and “git merge.”

Introduction to Embedded Linux - Module 04: Application Debug 04 - 1

Module 04: Application Debug

Introduction Code Composer Studio version 5 is the current iteration of Texas Instrument’s integrated development environment. This IDE can be used to program any of TI’s processors from the low-cost, ultra-low-power MSP430 all the way up to the ultra-performance Arm Cortex-A8 devices such as the AM335x.

CCSv5 is based on eclipse, an open-source IDE. This provides many advantages. Firstly, customers who are familiar with other eclipse-based IDEs will have less learning curve, and those who are not are likely to run into eclipse-based IDEs in the future. Secondly, there is a large community of eclipse plugins that can be used with CCSv5. Also, eclipse runs on both Windows and Linux host machines.

This module will introduce the basic features of CCSv5 and provide details on setting up a debugging environment.

Module Topics

04 - 2 Introduction to Embedded Linux - Module 04: Application Debug

Module Topics Module 04: Application Debug..................................................................................................................4-1

Module Topics ..........................................................................................................................................4-2

Intro to Makefiles .....................................................................................................................................4-3

Code Composer Studio Overview ............................................................................................................4-7

Setting up a CCS5 GDB Session ............................................................................................................ 4-13

Setting up a CCS5 JTAG Session ........................................................................................................... 4-16

Lab 4: Application Build and Debug ..................................................................................................... 4-17

Intro to Makefiles


Intro to Makefiles

Build Overview

Build Tool

Build Instructions

Source Files“Dependencies”

app.capp.cfgapp.h

Build Tool Goals:1. Build executable (target) from input files (dependencies) using build

instructions (commands)2. Build for multiple targets at once (e.g. ARM, X86, DSP)

app.x64Papp.xv5Tapp.x470MVapp.x86U

Executables “Targets”

app.oapp.lib

“D” “CMD” “T”

Solution: command line (e.g. cl6x, gcc) or scripting tool (gMake, etc.)

Command Line (Examples 1-2)

Example 1: create an object file (app.o) from an input file (app.c)

Might be more convenient to place commands in a script/batch file…makefile…

gcc –g –c app.c –o app.o

Example 2: create an executable (app.x86U) from an object file (app.o) gcc –g app.o –o app.x86U

“Commands”

command flag dependency flag target

Command Line

“Dependencies”

app.capp.o

app.oapp.x86U

“Targets”

“D” “CMD” “T”

-c = compile only-g = build with debug enabled-o = output filename

Intro to Makefiles


Basic Makefile with Rules

gMake

“Dependencies”

app.capp.o

app.oapp.x86U

“Targets”

“D” “CMD” “T”

One of the more common “scripting” tools is GNU Make, aka gMake, aka Make…gMake uses “rules” to specify build commands, dependencies and targetsGenerically, a RULE looks like this:

Remember Example 2? Let’s make this into a simple Makefile rule:gcc –g app.o –o app.x86U

command flag dependency flag target

Makefile

TARGET : DEPENDENCY[TAB] COMMANDS…

app.x86U : app.o

gcc –g app.o –o app.x86U

Becomes….RULE

Creating Your First Makefile

gMake

“Dependencies”

app.capp.o

app.oapp.x86U

“Targets”

“D” “CMD” “T”

Makefile

gcc –c –g app.c –o app.o

gcc –g app.o –o app.x86U Command Lines

# Makefile for app.x86U (goal)

app.x86U : app.ogcc –g app.o –o app.x86U

app.o : app.cgcc –g –c app.c –o app.o

Makefile

Intro to Makefiles


User-Defined Variables & Include Files

User-defined variables simplify your makefile and make it more readable.Include files can contain, for example, path statements for build tools. We use this method to place absolute paths into one file.If “-include path.mak” is used, the “-” tells gMake to keep going if errors exist.

“D” “CMD” “T”

include path.mak

CC := $(CC_DIR)gcc

CFLAGS := -g

LINK_FLAGS := -o

app.x86U : app.o

$(CC) $(CFLAGS) $^ $(LINK_FLAGS) $@

CC_DIR := /usr/bin/

...# other paths go here…

Examples:

makefile path.mak

Using Built-in Variables“D” “CMD” “T”

Simplify your makefile by using these built-in gMake variables:• $@ = Target• $^ = All Dependencies• $< = 1st Dependency Only

Scope of variables used is the current rule only.Example:

app.x86U: app.o

gcc –g app.o –o app.x86U

Original makefile…

app.x86U: app.o

gcc –g $^ –o $@

Becomes…

Intro to Makefiles


Templated Rules Using “%”Using pattern matching (or pattern substitution) can help simplify your makefile and help you remove explicit arguments. For example:

app.x86U : app.o main.o$(CC) $(CFLAGS) $^ -o $@

app.o : app.c$(CC) $(CFLAGS) -c $^ -o $@

main.o : main.c$(CC) $(CFLAGS) -c $^ -o $@

Original Makefile

app.x86U : app.o main.o$(CC) $(CFLAGS) $^ -o $@

%.o : %.c$(CC) $(CFLAGS) -c $^ -o $@

Makefile Using Pattern Matching

The .x rule depends on the .o files being built – that’s what kicks off the .o rules% is a shortcut for $(patsubst …), e.g. $(patsubst .c, .o)

Code Composer Studio Overview



What is Code Composer Studio?Integrated development environment for TI embedded processors

Includes debugger, compiler, editor, simulator, OS…

CCSv5 is based on “off the shelf” Eclipse

TI contributes changes directly to the open source communityDrop in Eclipse plug-ins from other vendors or take TI tools and drop them into an existing Eclipse environmentCCSv5 runs on a Windows or Linux host

Integrate additional toolsOS application development tools (Linux, Android…)Code analysis, source control…

Low cost!

CCSv5 Environment

Tabbed editor windows

Tab data displays togetherto save space

Fast view windows don’t displayUntil you click on them

Perspectives contain separatewindow arrangements depending

on what you are doing.

Customize toolbars & menus



Eclipse ProjectsCCSv5 is PROJECT-centricEclipse uses managed makefiles as their build scripts – as opposed to pjt filesEclipse projects are folder based

“Adding file” copies it to folder“Linking file” references original fileProject explorer shows folder contents

Project explorer lists functions

make file

PerspectivesPerspectives – a set of windows, views andmenus that correspond to a specific set of tasksTwo default perspectives are provided with CCSv5:

C/C++• Code Dev’t Views• Project Contents• Editor

Debug• Debug Views• Watch/Memory• Graphs, etc.

Users can customize perspectives and save them:



Two Default Build ConfigurationsBuild Configuration – a set of build options for the compiler and linker(e.g. optimization levels, include DIRs, debug symbols, etc.) CCSv5 comes standard with two DEFAULT build configs: Debug & Release:

User can modify compiler/linker options via “Build Options”:

User can create theirown config if desired

18Many more details on compiler options in a later chapter…

User Mode DebuggingWhen debugging user mode programs, you often only want to debug – hence stop –one thread or program. GDB (GNU Debugger) works well for this. (GDB discussed on next slide)Connection is usually Ethernet or serial-port

Kernel Mode DebugDebugging kernel code requires complete system access. You need KGDB (Ethernet) or scan-based (JTAG) debuggers for this.

Debugging & Debugger’s

A debugger lets you Pause a programExamine and change variablesStep through code

Code Composer Studio (CCSv5)Latest version of TI’s graphical software debugger (i.e. IDE)IDE – integrated development environment: which combines editing, building and debugging into a single toolBuilt on Eclipse platform; can install on top of standard EclipseAllows debugging via GDB (Ethernet/serial) or JTAG (scan-based)Free license for GDB debugging



LANGdbserver on target

RS232Putty,Teraterm,Hyperterminal, CCS Serial Terminal

Linux application debug setup

LANGdb via Code Composer Studio

Debug system (PC) Target system (Board)

• Physically the connections of a typical linux application debug system are shown below.

JTAG

Linux kernel and driver debug setup

Debug system (PC) Target system (Board)

• Physically the connections of a typical uboot, linux kernel or driver debug system are shown below.



Open source debugger that is often supplied with the toolchainIn this workshop, it’s included in the Code Sourcery packageGDB has a client/server nature:

GDB Server:First start gdbserver, specifying connection and app to be debuggedServer then runs your app, following gdb commands

GDB (i.e. debug client)Command-line oriented debuggerTelnet, Bash terminal, IDE

GDB : GNU Debugger

(gdb) target remote 192.168.1.122:10000(gdb) step(gdb) b 43 (gdb) run

EVM> gdbserver 192.168.1.122:10000 myAppListening on port 10000Remote debugging from host 192.168.1.1

Hello World

Tera Term

GDB ServerRuns your app for you, based on the GDB commands you send

Graphical Debug with GDBEclipse (CCSv5) and other IDE’s can translate actions to GDB cmds

Other than starting gdbserver, it means we don’t have to know GDB syntaxThe debug (host) system runs:

Its own OS (Linux, Windows, etc.)Debugger IDE (optional) and GdbTerminal app (Tera Term, putty, etc.) to control the target/evm environment

Host PCCCSv5 (Eclipse)

Target (EVM)RS-232

Terminal

Ethernet

CCSv5 (Eclipse)

The target system runs:Embedded OS Gdbserver that controls app’s execution

GDB

Embedded O/S (ie. Linux)

GDB Server

App

ControlsTarget



CCSv5 Licensing & Pricing

20

Item Description Price AnnualPlatinum Eval Tools Full tools with 120 day limit (all EMU) FREEPlatinum Bundle EVM, sim, XDS100 use FREE Platinum Node Lock Full tools tied to a machine $495 (1) $99Platinum Floating Full tools shared across machines $795 (1) $159Microcontroller Core MSP/C2000 code size limited FREEMicrocontroller Node Lock MSP/C2000 $445 $99

Licensing• Wide variety of options (node locked, floating, time based…)• All versions (full, DSK, free tools) use same image• Updates readily available via the internet

Pricing• Reasonable pricing – includes FREE options noted below• Annual subscription – $99 ($149 for floating)

- recommended option: purchase Dev Kit, use XDS100v1-2, & Free CCSv5

Setting up a CCS5 GDB Session



Remote Systems View (1)Window Show View Other… Remote Systems Remote Systems

Remote Systems View (2)Files: tells CCS how to view remote files on and transfer files to remote system

Processes: tells CCS how to view and manipulate remote processes (applications)

Shells: tells CCS how to launch remote applications for debugging



Remote System View – Files / Terminal

Setting Up CCSv5 Application DebugRun Debug Configurations New Launch Configuration

Use remote system explorer to launch remote gdbserver



Setting Up CCSv5 Application Debug

Specify version of Gnu Debugger to use

CCSv5 Attached Remote Debugger

Setting up a CCS5 JTAG Session


Setting up a CCS5 JTAG Session Creating a New Target Config File (.ccxml)Target Configuration – defines your “target” – i.e. emulator/device used, GEL scripts (replaces the old CCS Setup)

Create user-defined configurations (select based on chosen board)

“click”

Specify GEL script here

Advanced Tab

16More on GEL files...

What is a GEL File ?GEL – General Extension Language (not much help, but there you go…)

A GEL file is basically a “batch file” that sets up the CCS debugenvironment including:

16

• Memory Map• DDR Configuration• PINMUX• PSC• PLL

The board manufacturer (e.g. SD or LogicPD) supplies GEL fileswith each board.To create a “stand-alone” or “bootable” system, the user mustwrite code to perform these actions (optional chapter covers these details)

Lab 4: Application Build and Debug



Lab 4: Application Build and DebugA. Test Secure Shell (ssh) protocolB. Create ProjectC. Set up CCS Remote System Explorer ConnectionD. Set up CCS Debug Configuration




Introduction to Embedded Linux - Module 05: Linux Files 05 - 1

Module 05: Linux Files

Introduction The Linux operating system has a wide range of filesystem support for many different block storage devices. The ability to store and manipulate files on NAND and NOR flash, multimedia and secure digital cards, hard disk drives and other media is important for many systems.

This section begins with an overview of Linux drivers that is applicable both to storage media drivers and device drivers. This module then continues to two case studys: the Arago NAND flash driver and GPIO driver. Though GPIO is a peripheral, the Arago GPIO driver is manipulated via virtual files and programming GPIO is therefore more akin to file manipulation than standard device driver manipulation. The next chapter will then focus on device drivers.

Module Topics

05 - 2 Introduction to Embedded Linux - Module 05: Linux Files

Module Topics Module 05: Linux Files ..............................................................................................................................5-1

Module Topics ..........................................................................................................................................5-2

Driver Basics ...............................................................................................................................................5-3

NAND Flash Driver .................................................................................................................................. 5-11

GPIO.......................................................................................................................................................... 5-13 Lab 5: GPIO via Virtual Files ............................................................................................................... 5-15

Module Topics


Driver Basics

Kernel vs User Space

Kernel SpaceThe Linux kernel manages the machine's hardware via driversDrivers provide hardware abstraction and protectionDrivers execute within the Linux kernel’s context, and are inserted into the running Linux kernel or statically linked in when kernel is built

User Space(Applications)Cannot access peripherals or memory directlyMake requests to kernel to access peripherals or storage media

User Process 1

User Process 3

User Process 2LinuxKernel

APIDriver

RAM Memory

Storage

Peripherals

File Sys

MMU

API

API

User Access to Kernel Space

Kernel Space

User Space

audio driver video driver

harddrive

ATA driver

buffer buffer

Memoryprocess

main(){

func1();

func2();

…

/dev/dsp /dev/video0

/mypath/myfile

/dev/hda1

filesystem

Block – random Character - sequential

‘mounted’ to root file system

Module Topics


Four Steps to Accessing Drivers

1. Load the driver’s code into the kernel (insmod or static)

2. Create a virtual file to reference the driver using mknod

3. Mount block drivers using a filesystem (block drivers only)

4. Access resources using open, read, write and close




How to add modules to Linux Kernel:1. Static (built-in) Linux Kernel

v4l2

fbdev

dsp

audio

nfsd ext3

httpd

Change static configuration using...

Module Topics


Static Linux Kernel Configuration

#> make ARCH=arm CROSS_COMPILE=arm_v5t_le- menuconfig


# modprobe <mod_name>.ko [mod_properties]

Use modprobe command to dynamically add modules into the Linux kernelKeep statically built kernel small (to reduce size or boot-up time), then add functionality later with modprobemodprobe is also handy when developing kernel modules



How to add modules to Linux Kernel:1. Static (built-in)

2. Dynamic(modprobe)

.ko = kernel object

Linux Kernel

v4l2

fbdev

dsp

oss

nfsd ext3

httpd

Module Topics


Examining The Steps in More Detail…





Linux Driver Registration

Register new drivers with mknod (i.e. Make Node) command.Major number determines which driver is used (the name does not affect which driver is used). Most devices have number assigned by Linux community.Minor number is significant for some drivers; it could denote instance of given driver, or in our example, it refers to a specific buffer in the FBdev driver.

# mknod <name> <type> <major> <minor>

<name>: Node name (i.e. virtual file name)

<type>: b blockc character

<major>: Major number for the driver

<minor>: Minor number for the driver

Example: mknod /dev/fb/3 c 29 3

Useage: Fd = open("/dev/fb/3", O_RDWR);

Module Topics


Linux Device RegistrationLinux devices are registered in /dev directoryTwo ways to view registered devices:

cat /proc/devicesls –lsa command (as shown below) to list available drivers

/ # cd /dev

/dev # ls –lsa

0 brw-rw---- 1 root disk 0, 0 Jun 24 2004 /dev/hda

0 crw-rw---- 1 root uucp 4, 64 Mar 8 2004 /dev/ttyS0

0 crw------- 1 user root 14, 3 Jun 24 2004 /dev/dsp

0 crw------- 1 user root 29, 0 Jun 24 2004 /dev/fb/0

0 crw------- 1 user root 29, 1 Jun 24 2004 /dev/fb/1

block vs char

Permissions (user,group,all)

Major number

Minor number Name

/dev directory






Module Topics


Mounting Block Devices

Mounting a block driver into the filesystem gives access to the files on the device as a new directoryEasy manipulation of flash, hard drive, compact flash and other storage mediaUse mkfs.ext2, mkfs.jffs2, etc. to format a device with a given filesystem

/ # mkdir /media/part1

/ # ls /media/part1

user – Shell – Konsole

Initially empty

Mounting Block Devices

Unlike Windows, there is only one filesystem – therefore you must mount to a mount point (i.e. empty directory) in the root filesystemEasy manipulation of flash, hard drive, compact flash and other storage mediaUse mkfs.ext2, mkfs.jffs2, etc. to format a device with a given filesystemThe above example shows mounting an external harddrive into the root filesystem

user – Shell – Konsole

Now populated

Initially empty

* Try ls –l : adds linefeeds

$ mount –t vfat /dev/mmcblk0p1 /media/part1

$ ls /media/part1

MLO u-boot.bin uImage

$ mkdir /media/part1

$ ls /media/part1

Module Topics


Some Common Filesystem TypesHarddrive File systems:

ext2 Common general-purpose filesystemext3 Journaled filesystem -

Similar to ext2, but more robust against unexpected power-downvfat Windows “File Allocation Table” filesystem

Memory File systems:jffs2 Journaling flash filesystem (NOR flash)yaffs yet another flash filesystem (NAND flash)ramfs Filesystem for RAMcramfs Compressed RAM filesystem

Network File systems:nfs Share a remote linux filesystemsmbfs Share a remote Windows® filesystem






Module Topics


Accessing Files

Manipulating files from within user programs is as simple as…

myFileFd = fopen(“/mnt/harddrive/myfile”,”rw”);

fread ( aMyBuf, sizeof(int), len, myFileFd );

fwrite( aMyBuf, sizeof(int), len, myFileFd );

fclose( myFileFd );

Additionally, use fprintf and fscanf for more feature-rich file read and write capability

File descriptor / handle Directory previously mounted File to open… Permissions

File descriptor / handleArray to read into / write from # of itemssize of item

Module Topics


NAND Flash Driver

NAND Partitions

# cat /proc/mtd

dev: size erasesize name mtd0: 00020000 00020000 "SPL" mtd1: 00020000 00020000 "SPL.backup1" mtd2: 00020000 00020000 "SPL.backup2" mtd3: 00020000 00020000 "SPL.backup3" mtd4: 001e0000 00020000 "U-Boot" mtd5: 00020000 00020000 "U-Boot Env" mtd6: 00500000 00020000 "Kernel" mtd7: 0f880000 00020000 "File System"

The Memory Technology Device (mtd) driver defines seven fixed partitions of NAND. Unlike most block devices, these partitions cannot be changed without modifying and rebuilding the driver source.

Examples of Using NAND

# flash_eraseall /dev/mtd4

Erase NAND partition 4

# nandwrite –p /dev/mtd4 u-boot.img

Write u-boot into NAND partition 4

# ubiformat /dev/mtd7 –f ubi.img –s 512 –O 2048

Write a UBI image into NAND partition 7

UBI images are created with mkfs.ubifs and ubinize commands. For more information:http://processors.wiki.ti.com/index.php/UBIFS_Support

Module Topics


Mounting a UBI Volume# ubinfo# mtdinfo

# mkdir /mnt/ubifs# ubiattach /dev/ubi_ctrl –m 7 –O 2048# mount –t ubifs ubi0:rootfs /mnt/ubifs

ubiattach attaches mtd partition 7 to UBI

-O 2048 indicates NAND flash block size

UBI volumes are specified ubiX:YX device numberY Volume number (ubi0:0) or name (ubi0:rootfs)

Module Topics


GPIO

GPIO Driver (Terminal)

# echo 30 > /sys/class/gpio/export

1. Export GPIO pin for sysfs usage (Pin 30 in example)

# echo "out" > /sys/class/gpio/gpio30/direction

# echo "in" > /sys/class/gpio/gpio30/direction

2. Change the GPIO pin direction to in/out

# echo 1 > /sys/class/gpio/gpio30/value

# echo 0 > /sys/class/gpio/gpio30/value

# cat /sys/class/gpio/gpio30/value

3. Change the value (output) or read the value (input)

# echo 30 > /sys/class/gpio/unexport

4. Unexport GPIO pin (when no longer needed)

GPIO Driver (C code)sysfs virtual files can be manipulated from C code in same manner as regular files// echo "out" > /sys/class/gpio/gpio30/direction

pFile = fopen(“/sys/class/gpio/gpio30/direction”, “w”);

fwrite(“out”, 1, sizeof(“out”), pFile);

fclose(pFile);

// echo 1 > /sys/class/gpio/gpio30/value

pFile = fopen(“/sys/class/gpio/gpio30/value”, “w”);

fwrite(“1”, 1, 1, pFile);

// cat /sys/class/gpio/gpio30/value

fread(myArray, 1, 1, pFile);

fclose(pFile);

Module Topics


leds-gpio driver

/sys/devices/platform/leds-gpio/leds/am335x:EVM_SK:heartbeat/sys/devices/platform/leds-gpio/leds/am335x:EVM_SK:mmc0/sys/devices/platform/leds-gpio/leds/am335x:EVM_SK:usr0/sys/devices/platform/leds-gpio/leds/am335x:EVM_SK:usr1

# echo 1 > /sys/devices/platform/leds-gpio/leds/am335x\:EVM_SK\:usr0/brightness

1. Light the usr0 LED

In addition to standard (device-specific) GPIO driver,Arago provides the (platform-specific) leds-gpio driver:

Note that “\:” is used to designate “:” in the Linux terminal because “:” is a special character. “\” is called the escape character because it can be prepended to special characters to designate they are simple text.

led Triggering

# cat /sys/devices/platform/leds-gpio/leds/am335x\:EVM_SK\:heartbeat/triggernone nand-disk mmc0 mmc1 timer [heartbeat] rfkill0 phy0rx phy0tx phy0assoc phy0radio

# echo none > /sys/devices/platform/leds-gpio/leds/am335x\:EVM_SK\:heartbeat/trigger

To disable the heartbeat led

Setting up a trigger ties an LED to a kernel event

Brackets around [heartbeat] indicate this LED is configured to trigger on the system heartbeat event.

Lab 5: GPIO via Virtual Files




Boot board and test GPIO (terminal)A. Light LED from C applicationB. Blink LED from C application

solution_Astart

solution_B

lab05_git

solutionsmaster

HEAD




Introduction to Embedded Linux - Module 06: Linux Drivers 06 - 1

Module 06: Linux Drivers

Introduction A basic feature of nearly any modern operating system is the abstraction of peripherals via device drivers. Linux provides a basic open-read-write-close interface to peripheral drivers that is a close parallel to the file manipulation interface described in the previous module.

This module provides a brief discussion on the differences between the basic driver model and the file I/O model then delves into two case studies: the UART driver and the audio driver (ALSA). The module wraps up with a related side topic: Linux signal handling.

Module Topics

06 - 2 Introduction to Embedded Linux - Module 06: Linux Drivers

Module Topics Module 06: Linux Drivers .........................................................................................................................6-1

Module Topics ..........................................................................................................................................6-2

Driver Basics ...........................................................................................................................................6-3

UART Driver ............................................................................................................................................6-5

Advanced Linux Sound Architecture (ALSA) ...........................................................................................6-7

Signal Handling ..................................................................................................................................... 6-11

Lab 6: UART Driver .............................................................................................................................. 6-13

Driver Basics


Driver Basics

Files and Virtual Files (Review)

Kernel Space

User Space

audio driver video driver

harddrive

ATA driver

buffer buffer

Memoryprocess

main(){

func1();

func2();

…

/dev/dsp /dev/video0

/mypath/myfile

/dev/hda1

filesystem

Block – random Character - sequential

‘mounted’ to root file system

Accessing Files (Review)

Manipulating files from within user programs is as simple as…

myFileFd = fopen(“/mnt/harddrive/myfile”,”rw”);

fread ( aMyBuf, sizeof(int), len, myFileFd );

fwrite( aMyBuf, sizeof(int), len, myFileFd );

fclose( myFileFd );

Additionally, use fprintf and fscanf for more feature-rich file read and write capability

File descriptor / handle Directory previously mounted File to open… Permissions

File descriptor / handleArray to read into / write from # of itemssize of item

Driver Basics


Using Character Device Drivers

ioctl( soundFd, SNDCTL_DSP_SETFMT, &format);

Notes:len field is always in bytesMore complex drivers, such as V4L2 and FBDEV video drivers, have special requirements and typically use ioctl commands to perfrom reads and writes

Additionally, drivers use I/O control (ioctl) commands to set driver characteristics

Simple drivers use the same format as files:

soundFd = open(“/dev/dsp”, O_RDWR);

read ( soundFd, aMyBuf, len );

write( soundFd, aMyBuf, len );

close( soundFd );

beaglebone$ lsmod

g_mass_storage

beaglebone$ rmmod g_mass_storage

beaglebone$ modprobe g_ether

Dynamic Driver Example – USB

connect_etherusb.sh

The connect_etherusb.sh script manually removes the mass storage USB gadget driver from the Beaglebone’srunning kernel and then dynamically inserts the Ethernet-over-USB gadget driver.

UART Driver


UART Driver

TTY Teletype Terminal

Name “teletype terminal” derives from historical hardware device that is rarely used todayAll Linux textual terminals (shell, uart, modem, etc.) use the TTY standardBasic open, read, write and close calls to useCommon practice is to use the <termios.h> library in place of direct ioctl control calls.

(Left) Early TTYs printed to paper.

(Right) screens were later added

Serial Port Configuration (Part 1)#include <stdio.h>#include <stdlib.h>#include <unistd.h>#include <string.h>#include <fcntl.h>#include <termios.h>

// Simple function to configure a serial port to 1152008N1void configure_serial(int fd){

struct termios terminal_setting;

tcgetattr(fd, &terminal_setting);

// Set baud rate// Most drivers use input rate for bothcfsetispeed(&terminal_setting, B115200);cfsetospeed(&terminal_setting, B115200);

UART Driver


Serial Port Configuration (Part 2)

// clear number of bits fieldterminal_setting.c_cflag &= ~CSIZE;// set 8 bitsterminal_setting.c_cflag |= CS8;

// clear parity bit in flag (no parity)terminal_setting.c_cflag &= ~PARENB;

// clear the CSTOPB flag in the mask// CSTOPB = 1 : 2 stop bits// CSTOPB = 0 : 1 stop bitterminal_setting.c_cflag &= ~CSTOPB;

// send changes to terminal settings structure to kernel// TCSANOW flag forces immediate changetcsetattr(fd, TCSANOW, &terminal_setting);

}

Serial Driver “Hello World”int main( void ){

char hello[40]="hello world\n";int fd;

// Open serial devicefd = open("/dev/ttyO0", O_RDWR);

configure_serial(fd);

// Write a string (char array) to devicewrite( fd, hello, sizeof(hello));

// Close fd to allow other programs accessclose(fd);

return 0;}

Advanced Linux Sound Architecture (ALSA)



ALSA Applications

The ALSA driver provides 3 Linux applications to exercise the driver. While not fancy, record/play app’s are useful for testing. The mixer is useful for choosing inputs/outputs.The three app’s are:

arecord Record audio from an ALSA device to a file

aplay Play recorded audio over an ALSA device

amixer Select input sources and adjust relative volume levels

ALSA Library APIInformation Interface /proc/asound

Status and settings for ALSA driver.

Control Interface /dev/snd/controlCXControl hardware of system (e.g. adc, dac).

Mixer Interface /dev/snd/mixerControls volume and routing of on systems with multiple lines.

PCM Interface /dev/snd/pcmCXDXManages digital audio capture and playback; most commonly used.

Raw MIDI Interface* /dev/snd/midiCXDXRaw support for MIDI interfaces; user responsible for protocol/timing.

Sequencer Interface* /dev/snd/seqHigher-level interface for MIDI programming.

Timer Interface /dev/snd/timerTiming hardware used for synchronizing sound events.

* Not implemented in current TI provided driver.



ALSA Driver Structure

ALSA Library

ALSA Kernel APIControlPCM

snd_pcm_open() snd_pcm_read()

snd_pcm_hw_params() snd_pcm_writei()

Snd_pcm_close()

open() read() write()

close() ioctl()

ALSA driver supports standard open, read, write, close and ioctl, however most programmers use the ALSA user-space library calls (snd_pcm_xxx)

arecordaplayamixer

ALSA Driver StructureApplication

User SpaceKernel Space

ALSA Library

ALSA Kernel APIControl

ALSA Driver CoreH/W Codec

DriverMachine

DriverPlatform Driver

McBSP Driver

PCM

AM335xControl I/F

(I2C) System DMA McBSPAudio Codec

(TWL4030/AIC23)

ALSA app’s

Hardware



Opening and Closing Devices

Devices:hw:i,j i = card number, j = device numberdefault alias for hw:0,0

/ Open the device */

rc = sound_pcm_open( &handle, “default”, SND_PCM_STREAM_PLAYBACK, 0);

/* Close the device */

/* Drain call blocks until last data plays */

snd_pcm_drain(handle);

snd_pcm_close(handle);

ALSA Configuration Example/* Allocate a hardware parameters object. */

snd_pcm_hw_params_allocate(&params);

/* Fill it in with default values. */

snd_pcm_hw_params_any(handle, params);

/* Set the desired hardware parameters. */

/* Interleaved mode */

snd_pcm_hw_params_set_access(handle, params, SND_PCM_ACCESS_RW_INTERLEAVED);

/* Signed 16-bit little-endian format */

snd_pcm_hw_params_set_format(handle, params, SND_PCM_FORMAT_S16_LE);

/* Two channels (stereo) */

snd_pcm_hw_params_set_channels(handle, params, 2);

/* 44100 bits/second sampling rate (CD quality) */

val = 44100;

snd_pcm_hw_params_set_rate_near(handle, params, &val, &dir);

/* Write the parameters to the driver */

rc = snd_pcm_hw_params(handle, params);



ALSA Read/Write Example/* Use a buffer large enough to hold one period */

snd_pcm_hw_params_get_period_size(params, &frames, &dir);

size = frames * 4; /* 2 bytes/sample, 2 channels */

buffer = (char *) malloc(size);

while (loops-- > 0) {

rc = read(0, buffer, size);

if (rc < size) {

fprintf(stderr, "end of file on input\n");

break;

}

rc = snd_pcm_writei(handle, buffer, frames);

if (rc < 0)

fprintf(stderr, "error from writei: %s\n", snd_strerror(rc));

}

Signal Handling


Signal Handling

Linux SignalsA signal is an event generated by Linux in response to some condition, which may cause a process to take some action when it receives the signal.

“Raise” indicates the generation of a signalMemory segment violationsFloating-point processor errorsIllegal instructionsUser generated at terminalSend from one process (program) to another

“Catch” indicates the receipt of a signalApplication programmers may register signal handling routinesIf no user signal handler is registered, a default signal handler is used

Signals defined in signal.h

* Note, this is not a complete list

Signal Handling


Signal Registration Exampleint main(int argc, char *argv[ ]){

int status = EXIT_SUCCESS;void *audioThreadReturn;

/* Set the signal callback for Ctrl-C */signal(SIGINT, signal_handler);

/* Call audio thread function */audioThreadReturn = audio_thread_fxn((void *) &audio_env);

if( audioThreadReturn == AUDIO_THREAD_FAILURE ){printf("audio thread exited with FAILURE status\n");status = EXIT_FAILURE;

} elseprintf("audio thread exited with SUCCESS status\n");

exit(status);}

/* Callback called when SIGINT is sent to the process (Ctrl-C). */void signal_handler(int sig){

DBG("Ctrl-C pressed, cleaning up and exiting..\n");audio_env.quit = 1; // used as while loop condition

}

Lab 6: UART Driver


Lab 6: UART Driver

Lab 6: UART DriverBoot board and test sshRemove serial console

A. Simple UART DriverB. Variables over UARTC. UART Configuration (Examination)

Restore serial console

solution_Astart

lab06_git

solutionsmaster

HEAD

solution_C

solution_B

Lab 6: UART Driver



Introduction to Embedded Linux - Module 07: Linux Scheduler 07 - 1

Module 07: Linux Scheduler

Introduction Another common feature of nearly any operating system is the ability to run multiple tasks concurrently, often referred to as “multi-threading.” The Linux operating system has two primary features used for concurrent tasks. The first is a memory management feature via the Memory Management Unit (MMU) in which separate memory spaces are created for each process, i.e. application.

The second feature is the sharing of CPU cycles across different applications via separation into POSIX threads. The Linux scheduler also manages the context switching between different threads of execution, including saving and restoring the system stack, saving and restoring CPU registers and reprogramming of the memory management unit if necessary.

This module begins with an overview of processes and threads, then discusses thread synchronization using semaphore objects. The module wraps up with a discussion of the usage of the two primary scheduling methodologies for threads: realtime and timeslicing.

Module Topics

07 - 2 Introduction to Embedded Linux - Module 07: Linux Scheduler

Module Topics Module 07: Linux Scheduler .....................................................................................................................7-1

Module Topics ..........................................................................................................................................7-2

Linux Processes .......................................................................................................................................7-3

Linux Threads ..........................................................................................................................................7-6

Thread Synchronization ............................................................................................................................7-8

Using Real-Time Threads ........................................................................................................................ 7-11 Lab 7: Linux Scheduler .......................................................................................................................... 7-17

Linux Processes


Linux Processes

What is a Process?

main(){

func1();

func2();

…

Process AMemory

main(){

func3();

func4();

…

Process BMemory

main(){

func5();

func6();

…

Process CMemory

Process A

Process B

Process C

Physical Processor

Scheduling MethodologiesTime-Slicing Threads

Scheduler shares processor run time between all threads with greater time for higher priorityNo threads completely starveCorrects for non-”good citizen”threadsCan’t guarantee processor cycles even to highest priority threads.More context switching overhead

Realtime ThreadsLower priority threads won’t run unless higher priority threads block (i.e. pause)Requires “good citizen” threadsLow priority threads may starve

Lower priority threads never break high priority threadsLower context-switch overhead

Time-sliced threads have a “nieceness” value by which administrator may modify relative loadingLinux dynamically modifies processes’ time slice according to process behaviorWith realtime threads, the highest priority thread always runs until it blocks itself

Linux Processes


The Usefulness of Processes

// audio_video.c// handles audio and video in// a single application

int main(int argc, char *argv[]){

while(condition == TRUE){callAudioFxn();callVideoFxn();

}}

Option 1:

// audio.c, handles audio only

int main(int argc, char *argv[]) {while(condition == TRUE)

callAudioFxn();}

Audio and Video in a single Process

Option 2: Audio and Video in separate Processes

// video.c, handles video only

int main(int argc, char *argv[]) {while(condition == TRUE)

callVideoFxn();}

Splitting into two processes is helpful if: 1. audio and video occur at different rates 2. audio and video should be prioritized differently3. multiple channels of audio or video might be required (modularity)4. memory protection between audio and video is desired

Terminal Commands for Processes

# ps Lists currently running user processes# ps -e Lists all processes

# top Ranks processes in order of CPU usage

# kill <pid> Ends a running process

# renice +5 –p <pid> Changes time-slice ranking of a process(range +/- 20)

Linux Processes


Launching a Process – Terminal

Side Topic – Creating New Processes in C

Splits one executing process into two

with same environment

New process replacesold but maintains

previous environment

Launch new processand keep previous

process

All processes are split-off from the original process created at startupWhen using fork, both processes run the same code; to prevent this, test if newly created process and run another program – or exec to another programTo review, a process consists of:

Context (memory space, file descriptors)One (or more) threads

fork exec fork + exec

Linux Threads


Linux Threads

Processes and Threads

By default, each process contains one main thread of executionAdditional threads can be spawned within a process (pThreads)All threads within a process share global variables

Threads scheduled individually by priority – regardless of which process they reside withinNo thread isolation – a rogue pointer will probably bring down all threads in that process.

Process A Process B

Process A global vars

A1 M

ain w

/ loca

l var

s

A2 p

Thre

adw/

loca

l var

s

A3 p

Thre

adw/

loca

l var

s

B1 M

ain w

/ loca

l var

s

Process B global vars

Process Pipes

Threads vs Processes

Processes ThreadsMemory protectionEase of useStart-up cyclesContext switchShared globals no yesScheduled entity no yesEnvironment program function

Linux Threads


pThread Functions – Create & Exit

pthread_create(&video_thread, null, video_thread_fxn, …)

pthread_exit (NULL)

main

video_thread

What if there's nothing for main() to do?

#include <pthread.h>int pthread_create(pthread_t *thread, pthread_attr_t *attr,

void *(*start_routine)(void *), void *arg);pthread_join(pthread_t thread, void **retval);pthread_exit(void *retval);

pthread_create (&new,…)

pthread_exit (retval)

main blocked

new

Re-Joining Main

pthread_join (new)

pthread_create(&video_thread, null, video_thread_fxn, …)

pthread_exit (retval)

main

video_thread

Linux Threads


Thread Synchronization

Thread Synchronization (Polling)void *threadA(void *env){int test;while(1){

while(test != TRUE) {test = (volatile int) env->driverComplete;

}doSomething(env->bufferPtr);

}}

Thread A’s doSomething( ) function should only run after the driver completes reading in a new bufferPolling can be used to halt the thread in a spin loop until the driverComplete flag is thrown.But polling is inefficient because it wastes CPU cycles while the thread does nothing.

Polling(spin loop)

Thread Synchronization (Polling)

Start pollingfor devComplete

devComplete = TRUE

thread A(higher priority)

driver

Process data

Wasted cycles whilethread A does nothing!(and thread B starves)

Process data

devComplete = TRUE

thread B

Linux Threads


Thread Synchronization (Blocking)

void *threadA(void *env){while(1){

read(env->audioFd, env->bufferPtr, env->bufsize); doSomethingNext(env->bufferPtr);

}

Instead of polling on a flag, the thread blocks execution as a result of the driver’s read call

More efficient than polling because thread A doesn’t waste cycles waiting on the driver to fill the buffer

Blocking(waits till

complete)

Thread Synchronization (Blocking)

Driver “read” call

devComplete = TRUE


driver

Process dataProcess data

devComplete = TRUE

(blocked)

Semaphores are used to block a thread’s execution until occurrence of an event or freeing of a resourceMuch more efficient system

thread B

Thread blocks until driver fills buffer.No wasted cycles!

(thread B gets to fill time)

Linux Threads


Semaphores

#include <semaphore.h>void *threadA(void *env){sem_t mySem;sem_init(&mySem, 1, 0); // initial value of zerowhile(1){

sem_wait(&mySem);doSomethingNext(env->bufferPtr);

}}

A semaphore is the underlying mechanism of the read call that causes it to block

Blocking(waits till

complete)

Thread Synchronization (Semaphore)

sem_wait(…)

sem_post(…)


driver

Process dataProcess data

sem_post(…)

(blocked)

Semaphores are used to block a thread’s execution until occurrence of an event or freeing of a resourceMuch more efficient system

thread B

Thread blocks until driver fills buffer.No wasted cycles!

(thread B gets to fill time)

Linux Threads


Using Real-Time Threads

Time-Sliced A/V Application, >100% loadAudio Thread

Video Thread

Control Thread

Adding a new thread of the highest “niceness” (smallest time slice) may disrupt lower “niceness” threads (higher time slices)All threads share the pain of overloading, no thread has time to complete all of its processingNiceness values may be reconfigured, but system unpredictability will often cause future problemsIn general, what happens when your system reaches 100% loading?Will it degrade in a well planned way? What can you do about it?

Time-Sliced A/V Application Analysis

All threads suffer, but not equally:Audio thread real-time failure is highly perceptibleVideo thread failure is slightly perceptibleControl thread failure is not remotely perceptible

Note: Time-slicing may also cause real-time failure in systems that are <100% loaded due to increased thread latency

Audio Thread Audio thread completes 80% of samples

Video Thread Video thread drops 6 of 30 frames

Control Thread User response delayed 1mS

Linux Threads


Real-time A/V Application, >100% load

Audio thread is guaranteed the bandwidth it needsVideo thread takes the restControl thread never runs!

Audio Thread(priority 99)

Video Thread(priority 98)

Control Thread(priority 70)

Time-Sliced A/V Application Analysis

Still a problem:Audio thread completes as desiredVideo thread failure is practically inperceptibleControl thread never runs – User input is locked out

Audio Thread Audio thread completes, no distortion


Control Thread No user response

Linux Threads


Hybrid A/V Application, >100% load

Audio thread is guaranteed the bandwidth it needsVideo thread takes most of remaining bandwidthControl thread gets a small portion of remaining bandwidth

Audio Thread(priority 99)

Video Thread(pri 0, nice -5)

Control Thread(pri 0, nice +5)

Hybrid A/V Application Analysis

A good compromise:Audio thread completes as desiredVideo thread failure is barely perceptibleControl thread delayed response is acceptibleBottom Line: We have designed the system so that it

degrades gracefully


Control Thread User response delayed 100ms

Audio Thread Audio thread completes, no distortion

Linux Threads


Default Thread Scheduling

pThread attributes: NULL / default value:

stacksize PTHREAD_STACK_MIN… …

detachedstate PTHREAD_CREATE_JOINABLEschedpolicy SCHED_OTHER (time slicing)inheritsched PTHREAD_INHERIT_SCHEDschedparam.sched_priority 0

#include <pthread.h>…

pthread_create(&myThread, NULL, my_fxn,(void *) &audio_env);

Setting the second argument to NULL means the pthread is created with default attributes

pthread_create()

pthread_create: Creates a new thread and makes it executable. It can be called anynumber of times from anywhere within your code.

pthread_create arguments: thread: A unique identifier (i.e. handle) for the new thread. It is filled-in and

returned by pthread_create(). attr: An attribute object that for setting thread attributes.

Pass NULL to use default values. start_routine: The C function to be executed once the new thread is created.

arg: A single argument passed to start_routine. It must be passed by reference as a void pointer. Use NULL if no argument is to be passed (though that is not the case for our lab exercise).

Once created, threads are peers, and may create other threads.

pthread_create (&thread, attr, start_routine, arg)

Linux Threads


Scheduling Policy OptionsSCHED_OTHER SCHED_RR SCHED_FIFO

Sched Method Time Slicing Real-Time (RT)RT priority 0 1 to 99 1 to 99

Min niceness +20 n/a n/a

Max niceness -20 n/a n/a

Scope root or user root root

Time Sliced scheduling is specified with SCHED_OTHER:Niceness determines how much time slice a thread receives, where higher niceness value means less time slice Threads that block frequently are rewarded by Linux with lower niceness

Real-time threads use preemptive (i.e. priority-based) scheduling Higher priority threads always preempt lower priority threadsRT threads scheduled at the same priority are defined by their policy:

SCHED_FIFO: When it begins running, it will continue until it blocksSCHED_RR: "Round-Robin" will share with other threads at it’s

priority based on a deterministic time quantum

Real-time Thread Creation Procedure// Initialize the pthread_attr_t structure audioThreadAttrspthread_attr_init(&audioThreadAttrs);

// Set the inheritance value in audioThreadAttrs structurepthread_attr_setinheritsched(&audioThreadAttrs,

PTHREAD_EXPLICIT_SCHED);

// Set the scheduling policy for audioThreadAttrs structurepthread_attr_setschedpolicy(&audioThreadAttrs, SCHED_RR);

// Set the scheduler priority via audioThreadParams structaudioThreadParams.sched_priority = 99;pthread_attr_setschedparam(&audioThreadAttrs,

&audioThreadParams);

// Create the new thread using thread attributespthread_create(&audioThread, &audioThreadAttrs,

audio_thread_fxn, (void *) &audio_env);

Create attribute structure

Set attribute to real-time priority 99

Create thread with given attributes

Linux Threads


Linking the pthread Librarypthread stands for POSIX threadPOSIX threads were introduced to Linux in 1996, but are not widely used because of the (relatively) low overhead of using processes.What does POSIX mean?

IEEE POSIX committee defined POSIX 1003.1c standard for threads.Linux threads are modeled after this standard, though don’t completely adhere to it.

gcc GNU compiler collection. Invokes compiler, assembler and linker as necessary for specified source files.

-D_REENTRANT Defines the _REENTRANT symbol, which forces all included libraries to use reentrant functions.

-lpthread Link in the pthread (POSIX thread) library.

# gcc –D_REENTRANT myProg.c –o myprog.o –lpthread

#include <pthread.h>#include C compiler pre-processor statementpthread.h Function declarations for the posix thread library

Lab 7: Linux Scheduler




A. Creating a POSIX threadB. Using Realtime threadsC. Using Semaphores

solution_Astart

lab07_git

solutionsmaster

HEAD

solution_C

solution_B

Lab 7A: Timeslice Thread


Linux scheduler shares CPU between timesliced threads, so each thread gets a turn to run.



Lab 7B: Realtime Thread


The first realtime thread to run will lock out the second thread.Because delay function uses a for loop instead of sleep (blocking)

Lab 7C: Realtime + Semaphore


while(1){

sem_wait();

…

sem_post();

}

while(1){

sem_wait();

…

sem_post();

}

thread1 thread2

Introduction to Embedded Linux - Module 08: Networking 08 - 1

Module 08: Networking

Introduction Networking connectivity is a common requirement for many applications. Linux on the AM335x provides strong support for both wired and wireless IP communication. This module begins with a short review of basic networking concepts and then proceeds into in a discussion of various commonly used server/client protocols such as secure shell (ssh), telnet, file transfer protocol (ftp), dynamic host configuration protocol (dhcp) and dynamic domain name servers (ddns.)

The module ends with an-indepth study of the underlying protocol common to all of these server/client systems in a Linux environment: Berkeley sockets. Programming examples are shown for opening and closing Berkeley sockets on both the server and client.

Module Topics

08 - 2 Introduction to Embedded Linux - Module 08: Networking

Module Topics Module 08: Networking .............................................................................................................................8-1

Module Topics ..........................................................................................................................................8-2

Ethernet Basics ........................................................................................................................................8-3

Server/Client Protocols ............................................................................................................................8-6

Berkeley Sockets .......................................................................................................................................8-9

Lab 8: Berkeley Sockets ......................................................................................................................... 8-11

Ethernet Basics


Ethernet Basics

Networking References

FF.FF.FF.FF.FF.FF

255.255.255.255

Media Access Controller address is unique to a physical device

www.ti.com

IP address is assigned by network or network administrator Host name and domain name are resolved by domain name servers

Address Resolution Protocol (ARP) resolves MAC addresses from IP addressesDomain Name Service (DNS) resolves IP addresses from host and domain name

Sub-networks

FF.FF.FF.FF.FF.FF

255.255.255.255

2^48 MAC Addresses>>

2^32 IP Addresses

WAN

LAN

WAN = Wide Area Network“the cloud.” WAN addresses are unique (but may be dynamic)

LAN = Local Area Network (subnet.)IP addresses are not unique

Ethernet Basics


Sub-networks

WAN

LAN

If <Dest> & Netmask = <Source> & Netmask thensource and destination are on the same subnet.

Else, destination packet is forwarded to the WAN.

Sub-networks are formed using a netmask

255.255.255.255

Sub-network Example

203.114.28.8192.168.1.1

192.168.1.7 192.168.1.3192.168.1.5

WAN

LAN

Computer A sends a packet to IP address 192.168.1.7Computer A (192.168.1.5) & 255.255.255.0 = 192.168.1.0Destination & 255.255.255.0 = 192.168.1.0

This is a transmission within the subnet, packet is sent directly to destination.

netmask255.255.255.0

A B C

D

Ethernet Basics


Sub-network Example

203.114.28.8192.168.1.1

192.168.1.7 192.168.1.3192.168.1.5

WAN

LAN

Computer A sends a packet to IP address 116.97.23.47Computer A (192.168.1.5) & 255.255.255.0 = 192.168.1.0Destination & 255.255.255.0 = 116.97.23.0

Packet is forwarded to the Gateway to be sent to the wide area network.

netmask255.255.255.0

A B C

D (Gateway)

Server/Client Protocols



IP PortsService Portecho 7ftp 20/21ssh 22telnet 23nameserver 42http 80

In addition to an IP address, connection requests may specify a port number.Ports are generally used in order to route connection requests to the appropriate server.

Client/Server modelServer is a static background (daemon)

process, usually initiated at startup, that listens for requests from one or more clients.

Network Address Translation

203.114.28.8:1000

:1002 :1003:1001

WAN

LAN

The Network Address Translation (NAT) protocol allows the gateway to assign port numbers to individual endpoints within the subnet.In this example, Computer A, port 22 (ssh) is mapped by the gateway to 203.114.28.8:1001

A B C

D (Gateway)



Dynamic Host Configuration Protocol (DHCP)

DHCP server issues IP address, netmask, gateway, dns to DHCP clients.

Server installation (Ubuntu)# apt-get install dhcp3-serverServer configuration file/etc/dhcp3/dhcpd.conf

Domain Name ServiceDomains and subdomains are not required to correlate to subnetwork boundaries (although they often do.)

Server installation (Ubuntu)# apt-get install bind9Configuration files/etc/named.conf/var/bind/*.zone



inetd/xinetduser@ubuntu:~$ ls /etc/xinetd.dchargen daytime discard echo tftp time

service tftp{protocol = udpport = 69socket_type = dgramwait = yesuser = nobodyserver = /usr/sbin/in.tftpdserver_args = /tftpbootdisable = no}

• Beaglebone Arago distribution does not use xinetd• Many desktop distributions do, including Ubuntu• Ubuntu launches xinetd from /etc/rc5.d/S20xinetd

xinetd is a single server (daemon process) that launches various IP services (as opposed to having each service running independent servers.)

Berkeley Sockets


Berkeley Sockets

Berkeley Sockets Basic Procedure

sFD = socket(…);

connect(sFD, addr, …);// do reads and writesshutdown(sFD,…);close(sFD);

sFD = socket(…);bind(sFD, addr, …);listen(sFD, …);while(1){

cFD = accept(sFD,…);// do reads and writesshutdown(cFD,…);close(cFD);

}Client Server

Socket Types

sFD = socket(AF_UNIX, SOCK_STREAM, 0);Local Socket

sFD = socket(AF_INET, SOCK_STREAM, 0);TCP/IP Socket

sFD = socket(AF_INET, SOCK_DGRAM, 0);UDP/IP Socket

Final parameter to socket function is protocol. Protocol is typically determined completely by first two parameters, so that “0” (default) is usually passed.

Berkeley Sockets


Specifying Address and Port

struct sockaddr_in stSockAddr;

memset(&stSockAddr, 0, sizeof(stSockAddr));

stSockAddr.sin_family = AF_INET;

stSockAddr.sin_addr.s_addr = inet_addr("192.168.1.1");

stSockAddr.sin_port = htons(1100);

connect(SocketFD, (struct sockaddr *)&stSockAddr,sizeof(stSockAddr));

Client

bind(SocketFD,(struct sockaddr *)&stSockAddr,sizeof(stSockAddr))

Server

Server Detailslisten(int sFD, int backlog);

listen creates an incoming connection queuesocketFD is the file descriptorbacklog is the maximum number of connection

requests to hold in the queue

accept(int sFD, sockaddr *address, size_t *len);

address and len (of address struct) are used to return the address of the connecting client. If this is not of interest, NULL may be passed.

shutdown(int sFD, int how);

how may be SHUT_RD, SHUT_WR, SHUT_RDWRpossible to call with SHUT_RD followed by SHUT_WRshutdown informs TCP/IP stack to terminate session,

but does not close file descriptor. Many systems implement shutdown automatically in close, but best to always call.

Lab 8: Berkeley Sockets



Lab 8: Berkeley SocketsA. Network Configuration FilesB. Berkeley Socket ClientC. Build and Launch Host ServerD. Server Application

solution_Astart

lab08_git

solutionsmaster

solution_Astart

lab08_x86_server

solutionsmaster




Introduction to Embedded Linux - Module 09: Video and Graphics Drivers 09 - 1

Module 09: Video and Graphics Drivers

Introduction Linux developers commonly use two drivers for handling video and graphics. The first of these drivers is named “Video For Linux, 2” (V4L2) and is commonly used to capture or display moving video. The second is called the “Framebuffer Device” driver (FBDEV) and is commonly used to display graphics such as a graphical user interface or desktop environment, although it is possible to use FBDEV to display moving video as well.

This module will cover functionality overviews as well as application programming details of using the V4L2 and FBDEV drivers.

Module Topics

09 - 2 Introduction to Embedded Linux - Module 09: Video and Graphics Drivers

Module Topics Module 09: Video and Graphics Drivers ..................................................................................................9-1

Module Topics ..........................................................................................................................................9-2

Linux v4L2 Video Driver ...........................................................................................................................9-3

Using mmap .........................................................................................................................................9-6(Optional) v4L2 Coding ......................................................................................................................9-8

Linux FBdev Display Driver ................................................................................................................... 9-10

Module Topics


Linux v4L2 Video Driver v4l2 Driver Overview

v4l2 is a standard Linux video driver used in many linux systemsSupports video input and output

In this workshop we use it for video input only

Device node Node name: /dev/video0Uses major number 81

v4l2 spec: http://bytesex.org/v4lDriver source location:…/lsp/ti-davinci/drivers/media/davinci_vpfe.c

v4l2 Driver Queue Structureincoming (empty) queue

outgoing (full) queue

v4l2

driv

erow

ns b

uffe

r

appl

icat

ion

owns

buf

fer

Application takes ownership of a full video buffer from the outgoing driver queue using the VIDIOC_DQBUF ioctlAfter using the buffer, application returns ownership of the buffer to the driver by using VIDIOC_QBUF ioctl to place it on the incoming queue

Module Topics


v4l2 Enqueue and Dequeue

App

DQ

OQ

IQv4l2 driver

Buffers typically exist in driver’s memory spaceThe dequeue call makes the data available to the app


App

DQ

OQ

IQ

(empty)

v4l2 driver

Buffers typically exist in driver’s memory spaceThe dequeue call makes the buffer available to the app Even after DQ, buffers still exist in the driver’s memory space but not the application’s

1234…

Module Topics



1234…

Appread1234…OQ

IQ

(empty)

v4l2 driver

Buffers typically exist in driver’s memory spaceThe dequeue call makes the buffer available to the app Even after DQ, buffers still exist in the driver’s memory space but not the application’s

read and write operations copy buffers from driver’s memory space to app’s or vice-versa


1234…

App

OQ

IQ

(empty)

EQv4l2 driver

Buffers typically exist in driver’s memory spaceThese buffers exist in the driver’s memory space but not the application’s read and write operations copy buffers from driver’s memory space to app’s or vice-versa

Is there a better method than "read"?

1234…

Module Topics


Using mmap

mmap – A Better Way

1234…

IQ

App

AppdriverStandard read and write copy data from driver buffer to a new buffer in application process’s memory space

Use mmap to expand the application process’s memory space to include the driver bufferReturns a pointer to the location in the app’s memory space

read

1234…

1234…

(mmap)

OQ

IQ

OQ

DQ

EQ

driverEQ

1234…

DQ

v4l2 Queue Synchronization

App

DQ

OQ

IQ

X

XDriver fills IQ bufand places on OQ

v4l2 driver

The VIDIOC_DQBUF ioctl blocks the thread’s execution waits if until a buffer is available on the output queueWhen driver adds a new, full buffer to the output queue, the application process is releasedDequeue call completes and application resumes with the following set of commands

(empty)

Module Topics



App

DQ

OQ

IQ

X

XDriver fills IQ bufand places on OQ

v4l2 driver



App

DQ

OQ

IQv4l2 driver


Module Topics


v4l2 Synchronization

App

OQ

IQ

(empty)

v4l2 driver5678…

5678…

DQ


(Optional) v4L2 Coding

Commonly Used v4l2 ioctl’sData Structures

struct v4l2_requestbuffers req;req.count; // how many buffers to requestreq.type; // capture, output, overlayreq.memory; // mmap, userptr, overlay

struct v4l2_buffer buf;buf.index; // which driver bufferbuf.type; // matches req.typebuf.memory; // matches req.memorybuf.m.offset; // location of buffer in driver mem

Request the driver allocate a new buffer ioctl(fd, VIDIOC_REQBUFS, &req);

Get information on a driver buffer ioctl(fd, VIDIOC_QUERYBUF, &buf);

Enqueue and Dequeue buffers to/from driver ioctl(fd, VIDIOC_QBUF, &buf);Ioctl(fd, VIDIOC_DQBUF, &buf);

Module Topics


v4l2 Buffer Passing Procedure

A simple flow would be: (1) DQBUF the buffer, (2) map it into user space, (3) use the buffer, (4) unmap it, (5) put it back on the driver’s queueMore efficient code would map each driver buffer once during initialization, instead of mapping and unmapping within the loopAlternatively, later versions of the driver allow you to create the buffer in ‘user’ space and pass it to the driver

while(cond){ioctl(v4l2_input_fd, VIDIOC_DQBUF, &buf); bufPtr = mmap(NULL, // “start” address (ususally 0)

buf.length, // lengthPROT_READ | PROT_WRITE, // allowed use for map’d memoryMAP_SHARED, // allow sharing of mapped bufsv4l2_input_fd, // driver/file descriptorbuf.m.offset); // offset requested from “start”

doSomething(bufPtr, buf.length, ...);munmap(bufPtr, buf.length);ioctl(v4l2_input_fd, VIDIOC_QBUF, &buf);

}

Module Topics


Linux FBdev Display Driver FBdev Driver Overview

FBdev is a standard Linux video output driver used in many linux systemsCan be used to map the frame buffer of a display device into user spaceDevice nodes have major number 29Device nodes have a minor number x Uses /dev/fb/x node naming convention

Multiple Video/OSD Windows

Source: DirectFBOverview.pdf

Module Topics


Allows Pixel by Pixel Blending of OSD and Video WindowsUses an 8-bit, Attribute (Alpha Blending) Value

FF 0020406080A0D0

32-bit Color Format

8-bit Attribute

8-bit Red

8-bit Green

8-bit Blue

8-bit blending0x00: 00.0%, 100% Video0x20: 12.5%, 87.5% Video0x40: 25.0%, 75.0% Video

…0xA0: 75.0%, 25.0% Video0xFF: 100%, 00.0% Video

32-bit ARGB Pixel Value

For Each /dev/fb/x Video Plane

Named FBdev because it gives direct access to the display device’s frame bufferFBIOPAN_DISPLAY allows users to pan the active display region within a virtual display buffer

yoffset

xoffset

xres

yres

xres_virtual

yres_virtual

Module Topics


Ping-pong Buffers with FBdev

FBdev has no video buffer queue (provides direct access to the display device’s frame buffer)Use FBIOPAN_DISPLAY to switch between 2 or more buffers in the virtual buffer spaceUse FBIO_WAITFORVSYNC to block process until current buffer scan completes, then switch.

xres_virtual

yres_virtual

buffer0 (ping)

buffer1(pong)

offset = (0,0)

offset = (yres,0)

In our case...

Ping-pong Buffers with FBdev

FBdev has no video buffer queue (provides direct access to the display device’s frame buffer)Use FBIOPAN_DISPLAY to switch between 2 or more buffers in the virtual buffer spaceUse FBIO_WAITFORVSYNC to block process until current buffer scan completes, then switch.

xres_virtual

yres_virtual

buffer0 (ping)

buffer1(pong)

offset = (0,0)

offset = (yres,0)

Module Topics


Buffer SynchronizationpVirtualBuf = mmap(NULL,display_size * NUM_BUFS,

PROT_READ | PROT_WRITE,MAP_SHARED,FbdevFd, 0);

while(cond){// map next frame from virtual bufferdisplay_index = (display_index +1) % NUM_BUFS;ioctl(pFbdevFd, FBIOGET_VSCREENINFO, &vinfo);vinfo.yoffset = vinfo.yres * display_index;

// write pixels into next video frame genPicture(…);

// switch to next frameioctl(pFbdevFd, FBIOPAN_DISPLAY, &vinfo);

// wait for current frame to completeioctl(pFbdevFd, FBIO_WAITFORVSYNC, NULL);

}

yresbuffer 0 (ping)

xres

buffer 1 (pong)

Blocking on select()

Reasons to use select():Can block on multiple eventsAllows specification of a timeout value for blocking

int wait_for_frame(int fd) {struct timeval tv; // timeout valuefd_set fds; // set of file descriptors to wait on

FD_ZERO(&fds); // using a file descriptor set of only one FD_SET(fd, &fds); // value – passed in as function parameter

tv.tv_sec = 2; // timeout after 2 seconds if no new frame

// Use select to wait for next filled frameret = select(fd + 1, // largest file descr value to test

&fds, // set of fd’s to wait on “read”NULL, NULL, // fd’s to wait on write or error&tv); // timeout value

… }

Module Topics


Commonly Used FBdev ioctlData Structures

struct fb_fix_screeninfo myFixScreenInfo;myFixScreenInfo.smem_len; // length of framebuffer

struct fb_var_screeninfo myVarScreenInfo;myVarScreenInfo.xres; // visible pic resolutionmyVarScreenInfo.xres_virtual; // virtual pic resolutionmyVarScreenInfo.xoffset; // from virtual to vis

Get or put variable screen informationioctl(fd, FBIOGET_VSCREENINFO, &myVarScreenInfo);ioctl(fd, FBIOPUT_VSCREENINFO, &myVarScreenInfo);

Get fixed screen informationioctl(fd, FBIOGET_FSCREENINFO, &myFixScreenInfo);

We use Pan to switch output buffersioctl(fd, FBIOPAN_DISPLAY, &myVarScreenInfo);

After writing buffer and pan_display, wait for current to finishioctl(fd, FBIO_WAITFORVSYNC, NULL); // arg 3 is not used

Introduction to Embedded Linux - Module 10: Qtopia GUI Development 10 - 1

Module 10: Qtopia GUI Development

Introduction The previous module introduced FBDEV, the Linux device driver that is commonly used for the display of graphics. This driver, however, is very low level, with the display being specified in the form of a bitmap.

Typically a developer would prefer to have additional tools such as fonts for displaying text and an abstraction of various common GUI components such as text and input boxes. There are many packages in Linux that may be used for the development of a graphical user interface. One of these packages that is commonly used in the embedded space is called Qtopia (or “qt” for short.)

Qtopia provides abstractions for many commonly used GUI components (termed “widgets”) as well as providing font support and human interface device (HID) support to integrate mouse and keyboard inputs as well as touch-screen inputs. Furthermore, Qtopia has a feature-rich and easy to use development environment called QT creator. .

Module Topics

10 - 2 Introduction to Embedded Linux - Module 10: Qtopia GUI Development

Module Topics Module 10: Qtopia GUI Development .................................................................................................... 10-1

Module Topics ........................................................................................................................................ 10-2

Graphics Software Layers ...................................................................................................................... 10-3

Qtopia .................................................................................................................................................... 10-6

Graphics Software Layers


Graphics Software Layers Terminal vs. Desktop

A terminal is a text-based interface to Linux O/SCommands are interpreted by a shell program (such as BASH)A terminal may connect via RS-232, Ethernet, etc.xterm is a terminal which connects via the X window server, i.e. receives input via x11 HID and outputs to x11 displayMost applications which can be launched from the Desktop (i.e. a drop-down menu) can be equivalently launched by typing a command into a Linux terminal

Desktop Managers

Gnome and KDE are two of many Linux display managersDesktop managers provide a “Desktop” or similar environment (i.e. for handheld device)Applications (such as mplayer or xterm) typically interface directly to x11 and are therefore independent of the Display ManagerGnome display manager is “just another client” to x11A display manager isn’t required to run Linuxx11 isn’t required to run Linux, though it is required by many graphical applications



x11 Without Desktop

Session Manager XSM(x11 session manager)

Display Manager XDM(x11 Display Manager)

Window Manager x11 window manager

Display Server X server

Driver LinuxFBDEV framebuffer driver

Device AM335x

Gnome Desktop Environment

Desktop Environment

Session Manager

Display Manager

Window Manager x11 window manager

Display Server X server

Driver LinuxFBDEV framebuffer driver

Device AM335x

GDM(Gnome Display Manager)

Gnome Session Manager

Gnome Desktop

KDE ... as a quick comparison



Gnome Desktop EnvironmentDesktop Environment Presents a desktop environment.

Session Manager Manages a login session to a Window Manager.Allows a user to maintain the settings and state of a windowing environment.

Display Manager Manages one or more local and/or remote Display servers (usually via window managers) for a login session.

Window Manager Exposes independent, resizable virtual displays (windows) to applications.

Display Server Network-transparent interface to display driver.

Driver Exposes a bitmap-type interface (framebuffer) to the display hardware.

Looking at Gnome graphically ...

K Desktop EnvironmentKDE

(K Desktop Environment)KDE

(K Desktop Environment)

ksmserver(session mgr)

ksmserver(session mgr)

KDM(KDE Display manager)

KDM(KDE Display manager)

kwm(K window mgr)

kwm(K window mgr)

QT embedded (QT / e) QT over x11 (QT / x11)

(No Display Server, direct framebufferaccess via widget lib) X server

Linux FBDEV Framebuffer Driver

Linux FBDEV Framebuffer Driver

AM335x AM335x

Qtopia


Qtopia

» Qt is cross-platform application and UI

framework.

» Qt provides a well defined API that can make

development quick and easy.

» Webkit» Well accepted open source

web browser» Rapidly create real-time web

content and services» Use HTML and Java Script

integrated in native code

» 3D Graphics with OpenGL and OpenGL ES

» Easily incorporate 3D Graphics in your applications

» Get maximum graphics performance

» Multithreading support

» Network connectivity» Advanced GUI development

Qt SDK

Qt development toolsQt modular class library

GUIWebKit

Graphics ViewOpenGL

Multimedia

Core

XMLScriptingDatabaseNetwork UI Tests

BenchmarkingFont Engine

Cross-platform support

Qt Designer

Forms Builder

qmakeCross-Platform

Build Tool

Qt Linguist

I18N Tools

Qt Assistant

Help reader

Qt CreatorCross-platform IDE

Linux/X11

Embedded Linux

Windows CEWindows

QT Framework

9

Example Qtopia Apps and UIs

Qtopia


Sitara Linux Stack

Matrix Application Launcher

Qt Embedded

QWidgetQGLWidget

OpenGL ES

ARM Benchmarks

Power Manager

Web Browser

System Information

Sitara ARM Processor

Target Board

FBDEV

DSS2

McSPI Touchscreen EthernetV4L2 ALSA VISA

UARTI2C USB McBSP MMC

3D Graphics

Gstreamer/FFMPEG

MPEG4, H.264, MPEG2, AAC, …

Wifi BlueZ

USB Profiler WLAN GUI

“Hello World!”

#include <QApplication>#include <QLabel>

int main(int argc, char **argv){

QApplication app(argc, argv);

QLabel label("Hello World!");label.show();

return app.exec();}

Qtopia


Running “Hello World!”

• Run qmake inside the helloworld directory to create a project file

• qmake –project

• Run qmake again to create a Makefile from helloworld.pro

• qmake

• Run make to build the application

• make

• Application is built and ready in debug/ directory. Copy executable to your filesystem on your target and run.

QT Creator – Development tools• Downloading and setting up:

http://processors.wiki.ti.com/index.php/Qt_Creator_Embedded_Debugging_Setup

Qtopia


QT Creator – Drag and Drop Widgets (Forms)

QT Creator – Forms Stored via XML

The UI created on the previous slide is stored as .xmlQT Creator then generates the UI from this .xml file

Qtopia


QT Creator – C++ Objects

Alternately, users may program using C++ object classes for each widget

WidgetsQt UI framework is based on widgetsWidgets respond to UI events (key presses/mouse movements), and update their screen areaEach widget has a parent, that affects its behavior, and is embedded into itMost Qt classes are derived from QWidgetRefer to online documentation at

http://doc.qt.nokia.com/4.6/qwidget.htmlTip – Documentation is arranged using class names.

Qtopia


QWTPlotCurve QHBoxLayout QComboBoxQDoubleSpinBox

QPushButton QlabelQMainWindow QMessageBox

QSl ider

Widgets

Signals & SlotsSignals & Slots

Signals and slots are used for communication between objects. The signals and slots mechanism is a central feature of Qt and probably the part that differs most from the features provided by other frameworks.

SignalsEvents occur and cause a signal

Widgets contain a list of predefined signals, but you can subclass a widget to add your own signalExample – button press, or Process complete

Slots are the functions which are assigned to handle a signal.

Widgets contain a list of predefined slots.You can subclass a widget and add your own slots

Qtopia


Simple Signal/Slot Example

The signal “sliderMoved(int)” is generated whenever the horizontal slider is moved

By adding this signal to the “lcdNumber” “display(int)” slot, the LCD will display the value of the horizontal slider when it is moved.

Simple Signal/Slot Example

Here a GUI object signal is tied directly to another GUI object slot; however, programmers can also write C++

functions to interface to signals and slots, thus connecting their interface to back-end functionality.

Introduction to Embedded Linux - Customizing Linux Kernel for Fast Boot 11 - 1

Customizing Linux Kernel for Fast Boot

Introduction A common concern with developers using the Linux operating system is the boot time that is required to start the system from reset. The boot time for the system we have used in the class so far is about 40 seconds; however, this is an unoptimized system that has a large number of components and features enabled, many of which may not be needed.

There are a couple of techniques for reducing boot time. Two of the most important are removing features and components that will never be required and deferring the loading of those components that are not required for booting.

This module will show you how to create a custom kernel configuration, which is useful both for configuring a fast boot and for board porting. Techniques for improving boot time will then be shown, and finally, an overview of the Linux kernel source code is presented from the standpoint of Kernel porting, though this final topic is a high-level overview and much further knowledge is required to complete this extensive task.

Module Topics

11 - 2 Introduction to Embedded Linux - Customizing Linux Kernel for Fast Boot

Module Topics Customizing Linux Kernel for Fast Boot ............................................................................................... 11-1

Module Topics ........................................................................................................................................ 11-2

Acquiring Timing Information ............................................................................................................... 11-3

Kernel Boot Time Improvements ............................................................................................................ 11-5

Kernel Board Port .................................................................................................................................. 11-9

Acquiring Timing Information



Method 1: Timestamp printk

Pros: Timestamped at message generation

Cons: Potentially requires kernel rebuild (but default for TI SDK)

Only timestamps kernel messagesRequires printk, which adds to boot time!

$ make ARCH=arm menuconfigKernel hackingShow timing information on printks

Timestamped printk ExampleU-Boot SPL 2011.09 (Jul 26 2012 - 17:18:20)Texas Instruments Revision detection unimplementedNo daughter card presentOMAP SD/MMC: 0reading u-boot.img…Starting kernel ...Uncompressing Linux... done, booting the kernel.[ 0.000000] Linux version 3.2.0 (jenkins@sdit-build01)...[ 5.432098] kjournald starting. Commit interval 5 seconds[ 6.153228] EXT3-fs (mmcblk0p2): using internal journal[ 6.158721] EXT3-fs (mmcblk0p2): recovery complete[ 6.167755] EXT3-fs (mmcblk0p2): mounted filesystem [ 6.174987] VFS: Mounted root (ext3 filesystem) on device 179:2.[ 6.181640] Freeing init memory: 248K...ALSA: Restoring mixer settings...Configuring network interfaces... [ 12.417053] net eth0: CPSW phy found : id is : 0x4dd074udhcpc (v1.13.2) startedSending discover...

Timer starts when kernel begins booting

SPL/U-boot not profiled

Significant portion of kernel boot instrumented

init (rcX.d) scripts not instrumented



Method 2: Timestamp Serial Messages

Pros: Allows profiling of SBL/U-bootAllows benchmarking without printk overhead

Cons: Timestamps suffer serial buffering jitter

6

Profiling the Linux Kernel - Cont• Instrument kernel initialization. This will help you find which static drivers in the kernel are

taking the most time to initialize– Add “initcall_debug” to the bootargs in u-boot. With recent u-boots this can usually be done using:

setenv optargs initcall_debugsaveenv

– When the Linux system is booted you can view these initcall lines using “dmesg | grep initcall”[ xxxxx] initcall <init function> [<module>] returned 0 after <time> usecs

– These lines can be sorted using the commands below to help find the modules with the largest init times

• If CONFIG_PRINTK_TIME is enableddmesg | grep initcall | sort -k8 -n

• If CONFIG_PRINTK_TIME is not enableddmesg | grep initcall | sort -k6 -n

– It is possible to graphically view these initcall times using the bootgraph script in the Linux kernel sources. This requires CONFIG_PRINTK_TIME to be enabled

cat <bootlog> | perl <kernel source dir>/scripts/bootgraph.pl > boot.svg

• Additionaly you can use other tools to help you analyze the Linux kernel such as:– Linux Trace Toolkit (LTTng)

• Timing for certain kernel and process events– Oprofile

• System wide profiler– Bootchart

• Visualizes boot process

Kernel Boot Time Improvements



Step 1: Remove Unneeded Init ScriptsThe initialization process is launched by the Linux Kernel after the root filesystem is mountedBy default it is located at /sbin/init, but it can be specified as a kernel boot argument

/etc/inittab /etc/init.d

/etc/rcX.d

bootmisc.sh syslog

mountnfs.sh telnetd

networking thttpd


S10telnetd S20thttpd

S20syslog S60mountnfs

/sbin/init

Step 2: Remove Unneeded Kernel Modules

# insmod <mod_name>.ko [mod_properties]

Use insmod (short for insert module) command to dynamically add modules into the kernelKeep statically built kernel small (to reduce size or boot-up time), then add functionality later with insmodInsmod is also handy when developing kernel modules



1. Static(built-in)

2. Dynamic(insmod)

.ko = kernel object

Linux Kernel

v4l2

fbdev

dsp

oss

nfsd ext3

httpd



Kernel Build

host$ cd ti-sdk-am35x-evm_xxx/board_support/linux-xxx-psp-xxx

host$ make mrproper

host$ make ARCH=arm* am335x_evm_defconfig**

host$ make ARCH=arm menuconfig

host$ make ARCH=arm CROSS_COMPILE=arm-arago-linux-gnueabi- uImage

host$ make ARCH=arm CROSS_COMPILE=arm-arago-linux-gnueabi- modules

host$ make INSTALL_MOD_PATH=${HOME}/targetfs modules_install



* For available ARCH: host$ ls arch/** For available configs: host$ ls arch/arm/configs

RBL

Default Configurations

ubuntu$ make ARCH=arm am335x_evm_defconfig

ubuntu$ ls arch/arm/configsacs5k_defconfig fortunet_defconfig omap2plus_defconfigacs5k_tiny_defconfig g3evm_defconfig orion5x_defconfigafeb9260_defconfig g4evm_defconfig palmz72_defconfigag5evm_defconfig h3600_defconfig pcm027_defconfigam200epdkit_defconfig h5000_defconfig pcontrol_g20_defconfigam335x_evm_defconfig h7201_defconfig pleb_defconfig…

Note: these filenames must end in “_defconfig” to be recognized as default configurations.The default configuration file is used to generate a hidden file named “.config” at the top level of the kernel build directory.



Custom Configuration

Step 1: Start with an existing default configuration ubuntu$ make ARCH=arm am335x_evm_defconfig

Step 2: Modify the configurationubuntu$ make ARCH=arm menuconfig

Step 3: Save as a new default configurationubuntu$ copy .config arch/arm/am335x_fastboot_defconfig

Though not required, it is a good idea to save your custom configuration as a new kernel default configuration in case you need to modify later.

“make menuconfig” options



Other Boot OptimizationsChange Kernel Compile Flags Reduce filesystem sizeUse faster media to store kernel and filesystem

MMC/SD NAND FlashDefer module init calls

It is possibly to defer module init calls without having to build the modules dynamically. This requires kernel rebuildOnce the system booted the deferred calls can be executed by doing:

echo 1 > /proc/deferred_initcallsAdditional details at http://elinux.org/Deferred_Initcalls

Kernel Board Port


Kernel Board Port

16

The Target Port Starts with a Board File• Defines the Machine Name

• Declares Initialization Data for Peripherals being used

• Declare Pin Mux initialization Data

• Defines Initialization functions

• Provides required Machine Initialization functions

• Calls Common Initialization functions

• Summary is that this file defines several required elements required to boot a Linux kernel, one of several bricks in the wall so to speak.

17

Machine and Platform Files

17

arch/arm/mach-omap2/Makefile:

obj-$(CONFIG_MACH_AM335XEVM) += board-am335xevm.o

The Makefiles create variables named “platform-y,” “machine-y,” and “obj-y,” that define the directories and ultimately files to be added into the kernel binary.

arch/arm/Makefile:

machine-$(CONFIG_ARCH_OMAP3) := omap2plat-$(CONFIG_ARCH_OMAP) := omap…machdirs := $(patsubst %,arch/arm/mach-%/,$(machine-y))platdirs := $(patsubst %,arch/arm/plat-%/,$(plat-y))

arch/arm/plat-omap/Makefile:

obj-$(CONFIG_ARCH_OMAP3) += omap_device.o

Board

Kernel Board Port


Machine and Platform DefinitionUbuntu$ more arch/arm/configs/am335x_evm_defconfig…CONFIG_ARCH_OMAP=y…CONFIG_ARCH_OMAP2PLUS=y…CONFIG_MACH_OMAP_GENERIC=y…CONFIG_ARCH_OMAP2PLUS_TYPICAL=y…CONFIG_ARCH_OMAP3=y…CONFIG_SOC_OMAPTI81XX=y…CONFIG_SOC_OMAPAM33XX=y…CONFIG_MACH_OMAP3_BEAGLE=y…CONFIG_MACH_TI8168EVM=yCONFIG_MACH_TI8148EVM=yCONFIG_MACH_AM335XEVM=yCONFIG_MACH_AM335XIAEVM=y

Platform

Machine,Device

Board

19

How the Board File fits in the stack• Board Developer will spend

most of their time in the Board file.

• The Board file makes use of the machine shared common code

• The underlying port to the ARM Architecture Shared common code is already done and does not need to be looked at

• Finally everything rests on the Linux Kernel Shared Common Code.

• The lower in the stack you go the less direct interaction the board developer will or need to have.

Kernel Board Port


20

OMAP2+ Machine Shared Common Code

• There are several board files in the mach-omap2 directory. These board files typical use the support functions defined within this directory. Below is a sampling of some of the supporting common code, not all are mentioned here.

21

Board Porting

21

Much of the board-specific configuration of the Linux kernel is handled by the Machine and Platform files.

Machine = Board SpecificPlatform = Device Specific

So generally you will want to define a new Machine for a new board, but don’t need a new Platform.

Note, however, that in some cases the “CONFIG_ARCH_xxx” switches may be referenced in Linux drivers and other common code. (See next slide)

Kernel Board Port


Platform-Specific Driver SwitchesFor instance, searching on “CONFIG_ARCH_OMAP” locates (partial list:)

./sound/soc/omap/omap-mcbsp.h

./include/linux/usb/musb.h

./include/linux/omapfb.h

./drivers/tty/serial/8250.c

./drivers/usb/musb/musb_core.c

./drivers/usb/host/ohci-hcd.c

./drivers/usb/host/ohci-omap.c

./drivers/usb/host/ohci-omap.c

./drivers/input/keyboard/omap-keypad.c

./drivers/mfd/twl-core.c

./drivers/mfd/twl-core.c

./drivers/video/omap/omapfb.h

./drivers/video/omap/omapfb_main.c

./drivers/gpio/gpio-omap.c

./drivers/mtd/onenand/omap2.c

./drivers/net/ethernet/smsc/smc911x.h

./drivers/i2c/busses/i2c-omap.c…

Sometimes there is a TI-specific driver file. Sometimes there is simply a #define switch in a generic driver file.

ubuntu$ grep -R CONFIG_ARCH_OMAP .

Introduction to Embedded Linux - Optimizing and Customizing U-boot 12 - 1

Optimizing and Customizing U-boot

Introduction By modifying the Linux kernel and filesystem you can make significant reductions in boot time. In order to reach the optimal boot time, however, you will also need to modify U-boot and the boot arguments (bootargs) U-boot provides to the kernel.

This module will begin with a few simple bootargs changes that can shave a second or two off of boot time, then progresses to the concept of the initial RAM disk, which in some cases (such as booting from MMC/SD card) can remove three or four seconds from your boot time, and finally shows how to rebuild U-boot itself with configuration options that will reduce the size of U-boot and the MLO as well as reducing boot time.

Module Topics

12 - 2 Introduction to Embedded Linux - Optimizing and Customizing U-boot

Module Topics Optimizing and Customizing U-boot ...................................................................................................... 12-1

Module Topics ........................................................................................................................................ 12-2

Kernel Boot Option Improvements......................................................................................................... 12-3

Initial Ram Disk ..................................................................................................................................... 12-4

U-boot Rebuild ....................................................................................................................................... 12-6

Kernel Boot Option Improvements


Kernel Boot Option Improvements

3

Reduce Linux Boot – Bootargs (1)

• Pre-set loops per jiffy– You just need to measure this once– Find lpj value in kernel boot messages

• Calibrating delay loop… 718.02 BogoMIPS (lpj=3590144)– Add the “lpj=3590144” to the bootargs

• Use Static IP addressing where possible– If you don’t need networking then disable it altogether– If you want networking capability but not NFS then be sure to set

“ip=off” on the kernel command line.

• Set memory limit with “mem=“ option– Use only as much memory as needed to avoid DDR initialization

time

4

Reduce Linux Boot – Bootargs (2)

• Almost a second is spent verifying the kernel image checksum.– If your system doesn’t do anything about a bad image, why verify it?– This verification can be disabled by setting the “verify” u-boot parameter to n

at the u-boot command promptu-boot# setenv verify n

• Use the “quiet” bootargs option to disable routine status printfs to console

• Remove the console altogether– Remove “console=ttyO0,115200n8” from bootargs

Initial Ram Disk


Initial Ram Disk

6

Common Filesystems and Media

6

Media FilesystemMMC/SD EXT3 / EXT4 / FATHarddrive EXT3 / EXT4 / FATNAND / NOR Flash UBIFS / JFFS2 / YAFFSNetwork NFS / SMBFSDDR RAMFS / CRAMFS

Your choice of root filesystem type and storage media may has a significant impact on the time required to boot.

-- Initialization of memory interface -- Filesystem mount time-- Read/Write speed

7

INITRD Support Must be Enabled in Kernel

7

# # General setup # ... CONFIG_BLK_DEV_INITRD=y CONFIG_INITRAMFS_SOURCE="" ... # # UBI - Unsorted block images # ... CONFIG_BLK_DEV_RAM=y CONFIG_BLK_DEV_RAM_COUNT=1 CONFIG_BLK_DEV_RAM_SIZE=4000 CONFIG_BLK_DEV_RAM_BLOCKSIZE=1024

<Kernel>/.config

Note: In addition to enabling initrd support, the blocksize and count must be configured to match the Ramdisk image.

Initial Ram Disk


8

Creating a Ramdisk Image

8

# Ramdisk ConstantsRDSIZE=4000BLKSIZE=1024

# Create an empty ramdisk imagesudo dd if=/dev/zero of=/tmp/ramdisk.img bs=$BLKSIZE count=$RDSIZE

# Make it an ext2 mountable file systemsudo /sbin/mke2fs -F -m 0 -b $BLKSIZE /tmp/ramdisk.img $RDSIZE

# Mount it so that we can populatesudo mount /tmp/ramdisk.img /mnt/initrd -t ext2 -o loop=/dev/loop0

### Fill image with filesystem ###

# Finish up...sudo umount /mnt/initrdsudo gzip -9 /tmp/ramdisk.imgsudo cp /tmp/ramdisk.img.gz .

9

Ramdisk Boot Arguments

9

uEnv.txtbootargs=MEM=124M console=ttyO0,115200n8 root=/dev/ram0 rwrootfstype=ext2 initrd=0x87c00000,4M ip=none quiet lpj=3590144 init=/linuxrc

silent=true

uenvcmd=run mmc_load_uimage;fatload mmc 0 0x87c00000 ramdisk.img.gz 0x400000; bootm ${kloadaddr}

MLOu-boot.imguImageuEnv.txtramdisk.img.gz

MMCPartition 1

MEM=124 M128M – 4M Ramdisk

initrd=0x87c00000,4M0x87c00000 = start of DDR3

+ 124M offset,4M = length of initrd

U-boot Rebuild


U-boot Rebuild

MLO (U-boot_min) Build



host $ make ARCH=arm CROSS_COMPILE=arm-arago-linux-gnueabi- MLO



RBL

host$ make ARCH=<ARCH> CROSS_COMPILE=… <target>_config

<ARCH> and <Target> as defined in “boards.cfg”

U-Boot Build



host $ make ARCH=arm CROSS_COMPILE=arm-arago-linux-gnueabi- u-boot.img



Both MLO and u-boot.img may be built simultaneously using host $ cd ti-sdk-am335x-evm-xxx/board_support/u-boot-xxx

host $ make distcleanhost $ make ARCH=arm CROSS_COMPILE=arm-arago-linux-gnueabi- am335x_evm

RBL

host$ make ARCH=<ARCH> CROSS_COMPILE=… <target>

<ARCH> and <Target> as defined in “boards.cfg”

U-boot Rebuild


13

Translating Target into Source Directories

# Target ARCH CPU Board name Vendor SoC

##########################################################

davinci_dm355evm arm arm926ejs dm355evm davinci davinci



am3517_evm arm armv7 am3517evm logicpd omap3

am335x_evm arm armv7 am335x ti ti81xx

…

13

<U-boot>/boards.cfg

14

U-Boot Sources board/<Vendor>/<Board name>

arch/<ARCH>/include/asm/arch-<SoC>

include/configs/<Target>.h

<Vendor><Board><ARCH><SoC><Target>As definedIn “boards.cfg”

U-boot Rebuild


15

Configuration File Options – Boot Time

• Reduce environment size so that less data is read into memory– CONFIG_ENV_SIZE

• Remove Unnecessary Console Print Statements– CONFIG_SILENT_CONSOLE 1

• Set “bootdelay” to 0• Disable un-used peripherals

• #undef CONFIG_USB_*• #undef CONFIG_NAND• #undef CONFIG_MMC• #undef CONFIG_SPI• #undef CONFIG_FLASH_*

• Avoid long help text for the u-boot commands to save space– #undef CONFIG_SYS_LONGHELP

• Use simple parser - instead of hush– #undef CONFIG_SYS_HUSH_PARSER

host$ gedit include/configs/<target>.h

16

U-Boot Board File

• Defines Required interface functions for SPL and U-Boot

• One source file contains the code for both SPL and U-Boot and are separated by pre-processor flags

• SPL handles the initialization of clocks, DDR, Serial Port and PMIC

• Some functions are defined twice in both an SPL context and then again in a U-Boot context (s_init & board_init)

• The board file is where the developer will spend most of their effort for a port

Documents

SLIDES Intro Embedded Linux 3day Color