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| | This class is about developing software for embedded Linux. So far we have been doing all of our development on the Beagle. This works well for small (and not so small) programs. However, we are now moving into kernel development and that's best done on a more powerful host computer. In [[EBC Exercise 08 Installing Development Tools]] you learned how to download and install the cross-compilers and the source for kernel and u-boot. Now we'll use those tools. | | This class is about developing software for embedded Linux. So far we have been doing all of our development on the Beagle. This works well for small (and not so small) programs. However, we are now moving into kernel development and that's best done on a more powerful host computer. In [[EBC Exercise 08 Installing Development Tools]] you learned how to download and install the cross-compilers and the source for kernel and u-boot. Now we'll use those tools. |
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| − | First we'll check everything by compiling the Hello World program, then we'll try the kernel and u-boot.
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| | == Cross-compiling Hello World == | | == Cross-compiling Hello World == |
| | + | This shows how to cross-compile with compiler loaded with |
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| | + | host$ '''sudo apt-get install -y git lzop gcc-arm-linux-gnueabi uboot-mkimage''' |
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| | Listing 2-4 on page 29 of the text is an embedded version of Hello World. If you've set up your git repository you will find it in '''helloWorld.c''' when you do a''' git pull'''. Compile and run it on your host to be sure it works. | | Listing 2-4 on page 29 of the text is an embedded version of Hello World. If you've set up your git repository you will find it in '''helloWorld.c''' when you do a''' git pull'''. Compile and run it on your host to be sure it works. |
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| | This address (0x601020) is in our data section | | This address (0x601020) is in our data section |
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| − | Now that you know it's working, let's cross compile it. First set the paths to find the cross-compilers. Put the following in a file, call it ~/.oe/'''crossCompileEnv.sh'''. Make sure the path is correct for your system. This is for a 32-bit linux. | + | Now that you know it's working, let's cross compile it. First set the paths to find the cross-compiler. Put the following in a file, call it ~/.oe/'''crossCompile.sh'''. |
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| − | # add cross tools to your path
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| − | export ARM_TOOLCHAIN_PATH=~/BeagleBoard/oe/build/tmp-angstrom_v2012_05-eglibc/sysroots/i686-linux/usr/bin/armv7a-angstrom-linux-gnueabi
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| − | PATH=$PATH:$ARM_TOOLCHAIN_PATH/..
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| − | PATH=$ARM_TOOLCHAIN_PATH:$PATH
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| | export ARCH=arm | | export ARCH=arm |
| − | export CROSS_COMPILE=arm-angstrom-linux-gnueabi- | + | export CROSS_COMPILE=arm-linux-gnueabi- |
| − | | + | |
| − | Here it is for 64-bit
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| − | | + | |
| − | # add cross tools to your path
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| − | export ARM_TOOLCHAIN_PATH=~/BeagleBoard/oe/build/tmp-angstrom_v2012_05-eglibc/sysroots/x86_64-linux/usr/bin/armv7a-angstrom-linux-gnueabi
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| − | PATH=$PATH:$ARM_TOOLCHAIN_PATH/..
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| − | PATH=$ARM_TOOLCHAIN_PATH:$PATH
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| − | export ARCH=arm
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| − | export CROSS_COMPILE=arm-angstrom-linux-gnueabi-
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| | Now ''source'' the file and compile again. (Note: you only have to source once per terminal session.) | | Now ''source'' the file and compile again. (Note: you only have to source once per terminal session.) |
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| | The '''scp''' copies a.out to the beagle and the '''ssh''' runs the a.out on the beagle. Notice the address are very different from the host version. | | The '''scp''' copies a.out to the beagle and the '''ssh''' runs the a.out on the beagle. Notice the address are very different from the host version. |
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| − | == Stop Here, the rest hasn't been updated ==
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| − | == Finding the Kernel for the ETC 2012 image ==
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| − | We are looking for uImage, but we only want the 2.6.32 version. The last grep file the file in the '''boot''' directory. Several lines are printed, but the one I'm interested in is:
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| − | ''./build/tmp-angstrom_2010_x-eglibc/work/beagleboard-angstrom-linux-gnueabi/linux-omap-psp-2.6.32-r110b+gitr5fc29e7b2a76a64a739f857858ef0b98294aa155/git''/arch/arm/boot/uImage
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| − | The first part of the path (in italics) is the path to the kernel. Check it out.
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| − | host$ '''cd build/tmp-angstrom_2010_x-eglibc/work/beagleboard-angstrom-linux-gnueabi/linux-omap-psp-2.6.32-r110b+gitr5fc29e7b2a76a64a739f857858ef0b98294aa155/git'''
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| − | host$ '''ls -F'''
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| − | arch/ drivers/ Kbuild modules.order samples/ usr/
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| − | block/ firmware/ kernel/ Module.symvers scripts/ virt/
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| − | COPYING fs/ lib/ net/ security/ vmlinux*
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| − | CREDITS include/ MAINTAINERS patches/ sound/ vmlinux.o
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| − | crypto/ init/ Makefile README System.map
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| − | Documentation/ ipc/ mm/ REPORTING-BUGS tools/
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| − | We'll be learning what's in many of these over the next couple of weeks. Remember this location. Let's find uImage.
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| − | host$ '''cd arch/arm/boot; ls -shF'''
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| − | total 13M
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| − | 4.0K bootp/ 6.3M Image* 4.0K Makefile 3.0M zImage*
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| − | 4.0K compressed/ 4.0K install.sh 3.0M uImage
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| − | host$ '''ls -l uImage'''
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| − | -rw-r--r-- 1 beagle beagle 3144300 2011-12-08 01:02 uImage
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| − | It should have the date that you did the bitbake. Let's see if it runs on the Beagle
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| − | host$ '''scp uImage root@beagle:.'''
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| − | host$ '''ssh root@beagle'''
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| − | beagle$ '''cd /boot; ls -F'''
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| − | total 18M
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| − | 4.0K MLO@
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| − | 372K Module.symvers-2.6.32
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| − | 1.4M System.map-2.6.32
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| − | 80K config-2.6.32
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| − | 4.0K u-boot.bin@
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| − | 0 uImage@
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| − | 3.1M uImage-2.6.32
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| − | 8.9M vmlinux-2.6.32
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| − | beagle$ '''ls -l uImage'''
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| − | lrwxrwxrwx 1 www-data www-data 13 May 12 2011 uImage -> uImage-2.6.32
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| − |
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| − | So the uImage that is there is a symbolic link to '''uImage-2.6.32'''. Let's save the working uImage in a difference file and copy our new uImage in.
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| − | beagle$ '''mv uImage-2.6.32 uImage-2.6.32.orig'''
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| − | beagle$ '''mv ~/uImage uImage-2.6.32'''
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| − | And then reboot.
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| − | beagle$ '''shutdown -r now'''
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| − | After a couple of minutes your should be back and running again. Check and see if you are really running the new kernel.
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| − | beagle$ '''uname -a'''
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| − | Linux beagleboard 2.6.32 #3 PREEMPT Thu Dec 8 01:02:13 EST 2011 armv7l GNU/Linux
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| − | It worked! That's the date I compiled mine on.
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| − |
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| − | === Failed Kernel ===
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| − | Here's what I get when trying to run the 3.2.18 kernel on the A6A bone image.
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| − | <pre>
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| − | reading u-boot.img
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| − | reading u-boot.img
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| − | U-Boot 2011.09-00053-gb423c52 (Aug 10 2012 - 11:26:55)
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| − | I2C: ready
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| − | DRAM: 256 MiB
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| − | WARNING: Caches not enabled
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| − | No daughter card present
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| − | NAND: HW ECC Hamming Code selected
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| − | No NAND device found!!!
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| − | 0 MiB
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| − | MMC: OMAP SD/MMC: 0, OMAP SD/MMC: 1
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| − | *** Warning - readenv() failed, using default environment
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| − | Net: cpsw
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| − | Hit any key to stop autoboot: 0
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| − | SD/MMC found on device 0
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| − | reading uEnv.txt
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| − | 27 bytes read
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| − | Loaded environment from uEnv.txt
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| − | Importing environment from mmc ...
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| − | Loading file "/boot/uImage" from mmc device 0:2 xxa2
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| − | 4385656 bytes read
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| − | ## Booting kernel from Legacy Image at 80007fc0 ...
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| − | Image Name: Linux-3.2.18
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| − | Image Type: ARM Linux Kernel Image (uncompressed)
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| − | Data Size: 4385592 Bytes = 4.2 MiB
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| − | Load Address: 80008000
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| − | Entry Point: 80008000
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| − | Verifying Checksum ... OK
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| − | XIP Kernel Image ... OK
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| − | OK
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| − |
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| − | Starting kernel ...
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| − | </pre>
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| − |
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| − | == Installing a New U-boot ==
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| − | While we're at it, let's install a new U-boot. Note: The new U-boot runs for me, but doesn't boot the kernel, yet.
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| − | host$ '''cd ~/BeagleBoard/oe/build/tmp-angstrom_2010_x-eglibc/work/beagleboard-angstrom-linux-gnueabi/'''
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| − | host$ '''ls -F'''
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| − | linux-3.0.9-r110a/
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| − | linux-omap-psp-2.6.32-r110b+gitr5fc29e7b2a76a64a739f857858ef0b98294aa155/
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| − | shadow-4.1.4.3-r5/
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| − | u-boot-2011.09-r4/
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| − | There's the U-boot directory.
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| − | host$ cd u-boot-2011.09-r4/git/; ls -F
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| − | api/ COPYING fs/ mkconfig* post/ tools/
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| − | arch/ CREDITS include/ mmc_spl/ README u-boot*
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| − | board/ disk/ lib/ nand_spl/ rules.mk '''u-boot.bin'''
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| − | boards.cfg doc/ MAINTAINERS net/ snapshot.commit u-boot.lds
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| − | common/ drivers/ MAKEALL* onenand_ipl/ spl/ u-boot.map
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| − | config.mk examples/ Makefile patches/ System.map u-boot.srec
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| − | The file we want is right on the top level.
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| − | host$ '''scp u-boot.bin root@beagle:.'''
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| − | host$ '''ssh -X root@beagle'''
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| − | beagle$ '''cd /media/mmcblk0p1/; ls -F'''
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| − | MLO* u-boot.bin.broken* uEnv.txt*
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| − | U-BOOT.BIN* UIMAGE* uEnv/
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| − |
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| − | Be sure you are logged into the Beagle via the serial port, rather than using ssh. Otherwise you won't see the boot sequence that appears before the kernel is running.
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| − |
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| − | Here we've changed to the FAT partition which is where u-boot lives. Back it up and install the new one.
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| − | beagle$ '''mv U-BOOT-BIN u-boot-bin.orig'''
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| − | beagle$ '''mv ~/.u-boot-bin .'''
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| − | beagle$ '''shutdown -r now'''
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| − |
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| − | You should now see the new u-boot running if you are logged in via the serial port.
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| − |
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| − | == Compile via make ==
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| − |
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| − | When you use bitbake it sets up all the paths to use the correct cross compilers. You can also build the kernel or u-boot by using '''make''' if you set the paths like we did above.
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| − | If you haven't already, ''source'' the file and ''cd'' to the kernel directory and try a ''make''.
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| − |
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| − | host$ '''source ~/.oe/crossCompileEnv.sh'''
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| − | host$ '''cd ~/BeagleBoard/oe/build/tmp-angstrom_2010_x-eglibc/work/beagleboard-angstrom-linux-gnueabi/linux-omap-psp-2.6.32-r110b+gitr5fc29e7b2a76a64a739f857858ef0b98294aa155/git'''
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| − | host$ '''make xconfig'''
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| − | ([[EBC Exercise 13 Configuring the Kernel]] has details on configuring the kernel.)
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| − | To make the kernel run
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| − | host$ '''make uImage'''
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| − | Now, follow the instructions above to install your freshly compiled kernel.
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| − |
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| − | == Getting the A6A Kernel ==
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| − |
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| − | beagle$ '''cat /etc/angstrom-build-info'''
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| − | Configured Openembedded layers:
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| − | meta-angstrom = angstrom-v2012.05-yocto1.2:a029f5f5d19f788e2ab17227f35350ff5b6ca125
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| − | meta-oe
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| − | toolchain-layer
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| − | meta-efl
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| − | meta-gpe
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| − | meta-gnome
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| − | meta-xfce
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| − | meta-initramfs
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| − | meta-multimedia = denzil:b4488f4c012a64604b28bd2b6e93de411c34466d
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| − | meta-opie = master:efa3892b20a4ef80274e56e5633ebd62c16f9731
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| − | meta-java = master:3386ea6c96096f107f43f282f654e5afa456109e
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| − | meta-browser = master:c47f59df2e723495679c751cbdf6a8c6adec4b6a
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| − | meta-mono = master:83f8233b0498aadb18bf7605c3ba6c71d9e13a3a
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| − | meta-kde = master:5b0882d951cfd71886d423c190faaa7c7f932333
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| − | meta-ti = angstrom-staging:5364d0795bb27c2deb5a4e2df7d2f01ffb394cca
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| − | meta-efikamx = master:2c09a3a780b23448e8a6ca964256ff7f5ccba65d
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| − | meta-nslu2 = master:3d9fc951b05b4df476374b6fc3085ebac7f293ee
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| − | meta-htc
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| − | meta-nokia
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| − | meta-openmoko
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| − | meta-palm = master:2b106be01228f64298d6cb338f93088806594344
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| − | meta-handheld = master:1f05a15aceb4c3a19fa070463b58125b5658b2a9
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| − | meta-raspberrypi = denzil:34eef2ea4f5f24630dbb73b386861430167b8431
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| − | meta-intel
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| − | meta-sugarbay
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| − | meta-crownbay
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| − | meta-emenlow
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| − | meta-fishriver
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| − | meta-fri2
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| − | meta-jasperforest
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| − | meta-n450 = master:f75f9b6f68473eb0efac802409608f8389be0030
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| − | meta = denzil:b052427a6678b1b696f8c64cf0fdc55e6af86c48
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| − |
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| − | host$ '''cd BeagleBoard/oe/sources/meta-ti'''
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| − | host$ '''git checkout master'''
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| | {{YoderFoot}} | | {{YoderFoot}} |
This class is about developing software for embedded Linux. So far we have been doing all of our development on the Beagle. This works well for small (and not so small) programs. However, we are now moving into kernel development and that's best done on a more powerful host computer. In EBC Exercise 08 Installing Development Tools you learned how to download and install the cross-compilers and the source for kernel and u-boot. Now we'll use those tools.
Listing 2-4 on page 29 of the text is an embedded version of Hello World. If you've set up your git repository you will find it in helloWorld.c when you do a git pull. Compile and run it on your host to be sure it works.
Now that you know it's working, let's cross compile it. First set the paths to find the cross-compiler. Put the following in a file, call it ~/.oe/crossCompile.sh.
Embedded Linux Class by Mark A. Yoder
