Difference between revisions of "EBC Exercise 08a Cross-Compiling"

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{{YoderHead}}
 
{{YoderHead}}
  
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_4.4]] you learned how to download and install the cross compilers and the source for kernel and u-boot. Now we'll use those tools.
  
First we'll check everything by compiling the Hello World program, then we'll try the kernel and u-boot.
+
== Cross compiling Hello World ==
 +
Normally when you compile you compile on the machine that will run the code.  You can compile and run on the Bone, but sometimes (like when compiling the kernel) it's better to use a more powerful machine for the compiling.  First we'll compile ''helloWorld.c'' on the host computer and run it there, then we'll cross compile it on the host to run on the Bone.
  
== Cross-compiling 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.
 
  
 
  host$ '''gcc helloWorld.c'''
 
  host$ '''gcc helloWorld.c'''
 +
host$ '''file a.out'''
 +
a.out: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked,
 +
interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 3.2.0,
 +
BuildID[sha1]=049e80612d5735fda0966f6e23c637d345447f49, not stripped
 
  host$ '''./a.out'''
 
  host$ '''./a.out'''
  Hello, World! Main is executing at 0x400524
+
  Hello, World! Main is executing at 0x55f7f41f96aa
  This address (0x7fff8260bdf8) is in our stack frame
+
  This address (0x7ffd98d0ebd0) is in our stack frame
  This address (0x601038) is in our bss section
+
  This address (0x55f7f43fa018) is in our bss section
  This address (0x601020) is in our data section
+
  This address (0x55f7f43fa010) is in our data section
 +
 
 +
Now that you know it's working, let's cross compile it. First figure out what version of the cross compiler was loaded.
  
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.  
+
host$ '''cd BeagleBoard/bb-kernel/dl'''
 +
host$ '''ls'''
 +
gcc-arm-8.3-2019.03-x86_64-arm-linux-gnueabihf
 +
gcc-arm-8.3-2019.03-x86_64-arm-linux-gnueabihf.tar.xz
  
  # add cross tools to your path
+
Here we see two versions of the compiler have been loaded. Let's pick the newer one.
export ARM_TOOLCHAIN_PATH=~/BeagleBoard/oe/build/tmp-angstrom_v2012_05-eglibc/sysroots/i686-linux/usr/bin/armv7a-angstrom-linux-gnueabi
 
PATH=$PATH:$ARM_TOOLCHAIN_PATH/..
 
PATH=$ARM_TOOLCHAIN_PATH:$PATH 
 
export ARCH=arm
 
export CROSS_COMPILE=arm-angstrom-linux-gnueabi-
 
  
Here it is for 64-bit
+
Now set the paths to find the cross-compiler. Put the following in a file, call it '''~/crossCompileEnv.sh'''.
  
# add cross tools to your path
 
export ARM_TOOLCHAIN_PATH=~/BeagleBoard/oe/build/tmp-angstrom_v2012_05-eglibc/sysroots/x86_64-linux/usr/bin/armv7a-angstrom-linux-gnueabi
 
PATH=$PATH:$ARM_TOOLCHAIN_PATH/..
 
PATH=$ARM_TOOLCHAIN_PATH:$PATH 
 
 
  export ARCH=arm
 
  export ARCH=arm
  export CROSS_COMPILE=arm-angstrom-linux-gnueabi-
+
  export CROSS_COMPILE=arm-linux-gnueabihf-
 +
export PATH=$PATH:~/BeagleBoard/bb-kernel/dl/gcc-arm-8.3-2019.03-x86_64-arm-linux-gnueabihf/bin
 +
 
 +
Make sure the PATH you use goes to the bin directory where the cross compiler is installed.
  
 
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.)
  host$ '''source ~/.oe/crossCompileEnv.sh'''
+
  host$ '''source ~/crossCompileEnv.sh'''
 
  host$ '''${CROSS_COMPILE}gcc helloWorld.c'''
 
  host$ '''${CROSS_COMPILE}gcc helloWorld.c'''
 
  host$ '''file a.out'''
 
  host$ '''file a.out'''
  a.out: ELF 32-bit LSB executable, ARM, version 1 (SYSV), dynamically linked (uses shared libs), for GNU/Linux 2.6.16, not stripped
+
  a.out: ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV),
 +
dynamically linked, interpreter /lib/ld-linux-armhf.so.3,
 +
for GNU/Linux 3.2.0, BuildID[sha1]=17ab3588195851d9eb444f70e5069376cae3bdec,
 +
with debug_info, not stripped
  
 
The '''file''' command tells what's in the file.  In this case we have an ARM executable.  Success!  Now copy to your Beagle and run
 
The '''file''' command tells what's in the file.  In this case we have an ARM executable.  Success!  Now copy to your Beagle and run
  
  host$ '''scp a.out root@beagle:.'''
+
  host$ '''scp a.out debian@192.168.7.2:.'''
  host$ '''ssh root@beagle ./a.out'''
+
  host$ '''ssh debian@192.168.7.2 ./a.out'''
  Hello, World! Main is executing at 0x8374
+
  Hello, World! Main is executing at 0x103d5
  This address (0xbeb32d4c) is in our stack frame
+
  This address (0xbeb83c54) is in our stack frame
  This address (0x10650) is in our bss section
+
  This address (0x21030) is in our bss section
  This address (0x10648) is in our data section
+
  This address (0x21028) is in our data section
 
 
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.
 
 
 
== Finding the Kernel and Installing It ==
 
 
 
After doing [[EBC Exercise 08 Installing Development Tools]] you have a Beagle kernel on your host computer. Let's see if it works.
 
 
 
Once compiled the kernel is put in a file called '''uImage'''.  You may have seen it in the FAT partition on your SD card.  Let's find it on your host. One way to find it is
 
 
 
host$ '''cd ~/BeagleBoard/oe'''
 
host$ '''find . -name uImage'''
 
./build/tmp-angstrom_v2012_05-eglibc/work/beagleboard-angstrom-linux-gnueabi/linux-mainline-3.2.18-r121b/git/arch/arm/boot/uImage
 
./build/tmp-angstrom_v2012_05-eglibc/work/beagleboard-angstrom-linux-gnueabi/linux-mainline-3.2.18-r121b/sysroot-destdir/kernel/uImage
 
./build/tmp-angstrom_v2012_05-eglibc/work/beagleboard-angstrom-linux-gnueabi/linux-mainline-3.2.18-r121b/image/kernel/uImage
 
./build/tmp-angstrom_v2012_05-eglibc/sysroots/beagleboard/kernel/uImage
 
 
 
== Finding the Kernel for the ETC 2012 image ==
 
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:
 
''./build/tmp-angstrom_2010_x-eglibc/work/beagleboard-angstrom-linux-gnueabi/linux-omap-psp-2.6.32-r110b+gitr5fc29e7b2a76a64a739f857858ef0b98294aa155/git''/arch/arm/boot/uImage
 
 
 
The first part of the path (in italics) is the path to the kernel.  Check it out.
 
 
 
host$ '''cd build/tmp-angstrom_2010_x-eglibc/work/beagleboard-angstrom-linux-gnueabi/linux-omap-psp-2.6.32-r110b+gitr5fc29e7b2a76a64a739f857858ef0b98294aa155/git'''
 
host$ '''ls -F'''
 
arch/          drivers/  Kbuild      modules.order  samples/    usr/
 
block/          firmware/  kernel/      Module.symvers  scripts/    virt/
 
COPYING        fs/        lib/        net/            security/  vmlinux*
 
CREDITS        include/  MAINTAINERS  patches/        sound/      vmlinux.o
 
crypto/        init/      Makefile    README          System.map
 
Documentation/  ipc/      mm/          REPORTING-BUGS  tools/
 
 
 
We'll be learning what's in many of these over the next couple of weeks.  Remember this location.  Let's find uImage.
 
 
 
host$ '''cd arch/arm/boot; ls -shF'''
 
total 13M
 
4.0K bootp/      6.3M Image*      4.0K Makefile  3.0M zImage*
 
4.0K compressed/  4.0K install.sh  3.0M uImage
 
host$ '''ls -l uImage'''
 
-rw-r--r-- 1 beagle beagle 3144300 2011-12-08 01:02 uImage
 
 
 
It should have the date that you did the bitbake.  Let's see if it runs on the Beagle
 
host$ '''scp uImage root@beagle:.'''
 
host$ '''ssh root@beagle'''
 
beagle$ '''cd /boot; ls -F'''
 
total 18M
 
4.0K MLO@
 
372K Module.symvers-2.6.32
 
1.4M System.map-2.6.32
 
  80K config-2.6.32
 
4.0K u-boot.bin@
 
    0 uImage@
 
3.1M uImage-2.6.32
 
8.9M vmlinux-2.6.32
 
beagle$ '''ls -l uImage'''
 
lrwxrwxrwx 1 www-data www-data 13 May 12  2011 uImage -> uImage-2.6.32
 
 
 
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.
 
 
 
beagle$ '''mv uImage-2.6.32 uImage-2.6.32.orig'''
 
beagle$ '''mv ~/uImage uImage-2.6.32'''
 
 
 
And then reboot.
 
beagle$ '''shutdown -r now'''
 
 
 
After a couple of minutes your should be back and running again.  Check and see if you are really running the new kernel.
 
beagle$ '''uname -a'''
 
Linux beagleboard 2.6.32 #3 PREEMPT Thu Dec 8 01:02:13 EST 2011 armv7l GNU/Linux
 
 
 
It worked! That's the date I compiled mine on.
 
 
 
== Installing a New U-boot ==
 
 
 
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.
 
 
 
host$ '''cd ~/BeagleBoard/oe/build/tmp-angstrom_2010_x-eglibc/work/beagleboard-angstrom-linux-gnueabi/'''
 
host$ '''ls -F'''
 
linux-3.0.9-r110a/
 
linux-omap-psp-2.6.32-r110b+gitr5fc29e7b2a76a64a739f857858ef0b98294aa155/
 
shadow-4.1.4.3-r5/
 
u-boot-2011.09-r4/
 
 
 
There's the U-boot directory.
 
 
 
host$ cd u-boot-2011.09-r4/git/; ls -F
 
api/        COPYING    fs/          mkconfig*    post/            tools/
 
arch/      CREDITS    include/    mmc_spl/      README          u-boot*
 
board/      disk/      lib/        nand_spl/    rules.mk        '''u-boot.bin'''
 
boards.cfg  doc/      MAINTAINERS  net/          snapshot.commit  u-boot.lds
 
common/    drivers/  MAKEALL*    onenand_ipl/  spl/            u-boot.map
 
config.mk  examples/  Makefile    patches/      System.map      u-boot.srec
 
 
 
The file we want is right on the top level.
 
 
 
host$ '''scp u-boot.bin root@beagle:.'''
 
host$ '''ssh -X root@beagle'''
 
beagle$ '''cd /media/mmcblk0p1/; ls -F'''
 
MLO*        u-boot.bin.broken*  uEnv.txt*
 
U-BOOT.BIN*  UIMAGE*            uEnv/
 
 
 
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.
 
 
 
Here we've changed to the FAT partition which is where u-boot lives.  Back it up and install the new one.
 
 
 
beagle$ '''mv U-BOOT-BIN u-boot-bin.orig'''
 
beagle$ '''mv ~/.u-boot-bin .'''
 
beagle$ '''shutdown -r now'''
 
 
 
You should now see the new u-boot running if you are logged in via the serial port.
 
 
 
== Compile via make ==
 
 
 
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. 
 
 
 
If you haven't already, ''source'' the file and ''cd'' to the kernel directory and try a ''make''.
 
 
 
host$ '''source ~/.oe/crossCompileEnv.sh'''
 
host$ '''cd ~/BeagleBoard/oe/build/tmp-angstrom_2010_x-eglibc/work/beagleboard-angstrom-linux-gnueabi/linux-omap-psp-2.6.32-r110b+gitr5fc29e7b2a76a64a739f857858ef0b98294aa155/git'''
 
host$ '''make xconfig'''
 
 
 
([[EBC Exercise 13 Configuring the Kernel]] has details on configuring the kernel.)
 
 
 
To make the kernel run
 
 
 
host$ '''make uImage'''
 
 
 
Now, follow the instructions above to install your freshly compiled kernel.
 
 
 
== Getting the A6A Kernel ==
 
 
 
beagle$ '''cat /etc/angstrom-build-info'''
 
Configured Openembedded layers:
 
meta-angstrom    = angstrom-v2012.05-yocto1.2:a029f5f5d19f788e2ab17227f35350ff5b6ca125
 
meta-oe         
 
toolchain-layer 
 
meta-efl         
 
meta-gpe         
 
meta-gnome       
 
meta-xfce       
 
meta-initramfs   
 
meta-multimedia  = denzil:b4488f4c012a64604b28bd2b6e93de411c34466d
 
meta-opie        = master:efa3892b20a4ef80274e56e5633ebd62c16f9731
 
meta-java        = master:3386ea6c96096f107f43f282f654e5afa456109e
 
meta-browser      = master:c47f59df2e723495679c751cbdf6a8c6adec4b6a
 
meta-mono        = master:83f8233b0498aadb18bf7605c3ba6c71d9e13a3a
 
meta-kde          = master:5b0882d951cfd71886d423c190faaa7c7f932333
 
meta-ti          = angstrom-staging:5364d0795bb27c2deb5a4e2df7d2f01ffb394cca
 
meta-efikamx      = master:2c09a3a780b23448e8a6ca964256ff7f5ccba65d
 
meta-nslu2        = master:3d9fc951b05b4df476374b6fc3085ebac7f293ee
 
meta-htc         
 
meta-nokia       
 
meta-openmoko   
 
meta-palm        = master:2b106be01228f64298d6cb338f93088806594344
 
meta-handheld    = master:1f05a15aceb4c3a19fa070463b58125b5658b2a9
 
meta-raspberrypi  = denzil:34eef2ea4f5f24630dbb73b386861430167b8431
 
meta-intel       
 
meta-sugarbay   
 
meta-crownbay   
 
meta-emenlow     
 
meta-fishriver   
 
meta-fri2       
 
meta-jasperforest
 
meta-n450        = master:f75f9b6f68473eb0efac802409608f8389be0030
 
meta              = denzil:b052427a6678b1b696f8c64cf0fdc55e6af86c48
 
  
host$ '''cd BeagleBoard/oe/sources/meta-ti'''
+
The '''scp''' copies ''a.out'' to the beagle and the '''ssh''' runs the ''a.out'' on the beagle. Notice the addresses are very different from the host version.
host$ '''git checkout master'''
 
  
 
{{YoderFoot}}
 
{{YoderFoot}}

Latest revision as of 11:21, 20 September 2019

thumb‎ Embedded Linux Class by Mark A. Yoder


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_4.4 you learned how to download and install the cross compilers and the source for kernel and u-boot. Now we'll use those tools.

Cross compiling Hello World

Normally when you compile you compile on the machine that will run the code. You can compile and run on the Bone, but sometimes (like when compiling the kernel) it's better to use a more powerful machine for the compiling. First we'll compile helloWorld.c on the host computer and run it there, then we'll cross compile it on the host to run on the Bone.

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.

host$ gcc helloWorld.c
host$ file a.out
a.out: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked,
interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 3.2.0,
BuildID[sha1]=049e80612d5735fda0966f6e23c637d345447f49, not stripped
host$ ./a.out
Hello, World! Main is executing at 0x55f7f41f96aa
This address (0x7ffd98d0ebd0) is in our stack frame
This address (0x55f7f43fa018) is in our bss section
This address (0x55f7f43fa010) is in our data section

Now that you know it's working, let's cross compile it. First figure out what version of the cross compiler was loaded.

host$ cd BeagleBoard/bb-kernel/dl
host$ ls
gcc-arm-8.3-2019.03-x86_64-arm-linux-gnueabihf
gcc-arm-8.3-2019.03-x86_64-arm-linux-gnueabihf.tar.xz

Here we see two versions of the compiler have been loaded. Let's pick the newer one.

Now set the paths to find the cross-compiler. Put the following in a file, call it ~/crossCompileEnv.sh.

export ARCH=arm
export CROSS_COMPILE=arm-linux-gnueabihf-
export PATH=$PATH:~/BeagleBoard/bb-kernel/dl/gcc-arm-8.3-2019.03-x86_64-arm-linux-gnueabihf/bin

Make sure the PATH you use goes to the bin directory where the cross compiler is installed.

Now source the file and compile again. (Note: you only have to source once per terminal session.)

host$ source ~/crossCompileEnv.sh
host$ ${CROSS_COMPILE}gcc helloWorld.c
host$ file a.out
a.out: ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV),
dynamically linked, interpreter /lib/ld-linux-armhf.so.3,
for GNU/Linux 3.2.0, BuildID[sha1]=17ab3588195851d9eb444f70e5069376cae3bdec,
with debug_info, not stripped

The file command tells what's in the file. In this case we have an ARM executable. Success! Now copy to your Beagle and run

host$ scp a.out debian@192.168.7.2:.
host$ ssh debian@192.168.7.2 ./a.out
Hello, World! Main is executing at 0x103d5
This address (0xbeb83c54) is in our stack frame
This address (0x21030) is in our bss section
This address (0x21028) is in our data section

The scp copies a.out to the beagle and the ssh runs the a.out on the beagle. Notice the addresses are very different from the host version.




thumb‎ Embedded Linux Class by Mark A. Yoder