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

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[[Category:ECE497]]
 
[[Category:ECE497]]
 
[[Category: BeagleBoard]]
 
[[Category: BeagleBoard]]
 +
{{YoderHead}}
  
This class is about developing software for embedded Linux. The [http://elinux.org/Main_Page eLinux site] is a good source for embedded Linux in general. There are many ongoing embedded efforts going on many platforms. Poke around the site a while to get a feel for what's happening.
+
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.
  
We are going to use the [http://www.angstrom-distribution.org Ångström Distribution]It's available many platforms. Look around the site, you may recognize some of them.
+
== 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 compilingFirst 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.
  
== Get my setup from dfs ==
+
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.
  
I like to keep all things Beagle in a BeagleBoard directory. Here's how to match my setup:
+
host$ '''gcc helloWorld.c'''
<pre>
+
host$ '''file a.out'''
$ cd
+
a.out: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV),
$ mkdir -p BeagleBoard/oe
+
  dynamically linked (uses shared libs), for GNU/Linux 2.6.24,
$ cd BeagleBoard
+
  BuildID[sha1]=0x357e34e90f7c32d414368d69cc06d0aed59acf1c, not stripped
$ sftp username@dfs.rose-hulman.edu
+
host$ '''./a.out'''
Connecting to dfs.rose-hulman.edu...
+
Hello, World! Main is executing at 0x400524
username@rose-hulman.edu's password:
+
This address (0x7fff8260bdf8) is in our stack frame
sftp> cd Users/Y/yoder/Shared/BeagleBoard/oe
+
This address (0x601038) is in our bss section
sftp> ls
+
This address (0x601020) is in our data section
sftp> get oebb.sh.tar.gz
 
sftp> get sources.tar.gz
 
sftp> get build.tar.gz
 
exit
 
$ cd oe
 
$ tar xvf oebb.sh.tar.gz
 
$ tar xvf sources.tar.gz
 
$ tar xvf build.tar.gz
 
</pre>
 
  
Once you have everything in place you need to create the script that will get the environmental variables.
+
Now that you know it's working, let's cross compile it. First figure out what version of the cross compiler was loaded.
  
<pre>
+
host$ '''cd BeagleBoard/bb-kernel/dl'''
$ rm -rf build/conf
+
host$ '''ls'''
$ ./oebb.sh config beagleboard
+
gcc-linaro-5.4.1-2017.05-x86_64_arm-linux-gnueabihf
</pre>
+
gcc-linaro-5.4.1-2017.05-x86_64_arm-linux-gnueabihf.tar.xz
The first command removes the configuration files that were set up for my machineThe second command will create them for your machines. It will also create the file <code>~/.oe/environment-2008</code> and make sure your repositories are up to date.
+
gcc-linaro-7.1.1-2017.08-x86_64_arm-linux-gnueabihf
 +
  gcc-linaro-7.1.1-2017.08-x86_64_arm-linux-gnueabihf.tar.xz
  
One last thing is to
+
Here we see two versions of the compiler have been loaded.  Let's pick the newer one.
  
<pre>
+
Now set the paths to find the cross-compiler. Put the following in a file, call it '''~/crossCompileEnv.sh'''.
$ cd build/tmp-angstrom_2008_1
 
$ rm saved_tmpdir
 
</pre>
 
The <code>saved_tmpdir</code> file remembers where you last had your TMPDIR. Removing the file makes it forget that you've moved things since the time I built everything.
 
  
== Compile the Kernel and u-boot via bitbake ==
+
export ARCH=arm
 +
export CROSS_COMPILE=arm-linux-gnueabihf-
 +
export PATH=$PATH:~/BeagleBoard/bb-kernel/dl/gcc-linaro-7.1.1-2017.08-x86_64_arm-linux-gnueabihf/bin
 +
Make sure the PATH you use goes to the bin directory where the cross compiler is installed.
  
Before bitbaking be sure to source this file:
+
Now ''source'' the file and compile again. (Note: you only have to source once per terminal session.)
<pre>
+
host$ '''source ~/crossCompileEnv.sh'''
$ source ~/.oe/environment-2008
+
host$ '''${CROSS_COMPILE}gcc helloWorld.c'''
</pre>
+
host$ '''file a.out'''
Now you can now compile your own kernel and u-boot:
+
a.out: ELF 32-bit LSB  executable, ARM, EABI5 version 1 (SYSV),
<pre>
+
  dynamically linked (uses shared libs), for GNU/Linux 2.6.32,
$ time bitbake linux-omap-psp-2.6.32
+
  BuildID[sha1]=b9222cbcee442470c7b89ac294e392a631c82264, not stripped
$ time bitbake u-boot
 
</pre>
 
I've added the <code>time</code> command to the bitbake to see how long it takes. Tell me how long it takes on your system.
 
  
== Compile via make ==
+
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
  
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 yourselfHere's what you need to do.
+
host$ '''scp a.out debian@192.168.7.2:.'''
<pre>
+
  host$ '''ssh debian@192.168.7.2 ./a.out'''
$
+
Hello, World! Main is executing at 0x8374
</pre>
+
This address (0xbeb32d4c) is in our stack frame
If you would prefer to maintain your own kernel source tree outside of OE, see these directions:
+
This address (0x10650) is in our bss section
[[BeagleBoardLinuxKernel]]
+
This address (0x10648) is in our data section
  
Alternatively it is possible to run the official omap branch of the linux kernel. Take a peek at this page.
+
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.
[[BeagleBoard#Linux_kernel]] (Please continue reading for the modifications I needed)
 
  
*Since we are using OE, our paths are set up slightly different, I have made the relevant changes below that I needed to do it manually.  Take note on the second path command is arch specific (if you get an error about mkimage not being found, make sure you have the second path right)
+
{{YoderFoot}}
<pre>
 
PATH=~/oe/angstrom-dev/cross/armv7a/bin:~/oe/angstrom-dev/staging/i686-linux/usr/bin:$PATH  # add cross tools to your path
 
make ARCH=arm CROSS_COMPILE=arm-angstrom-linux-gnueabi- distclean
 
make ARCH=arm CROSS_COMPILE=arm-angstrom-linux-gnueabi- omap3_beagle_defconfig
 
make ARCH=arm CROSS_COMPILE=arm-angstrom-linux-gnueabi- menuconfig  # only needed if you want to change the default configuration
 
make ARCH=arm CROSS_COMPILE=arm-angstrom-linux-gnueabi- uImage
 
</pre>
 
 
 
* It is important to note that the kernel in the official branch will be newer then the ones that OE provides (2.6.33 at the time of this writing), and as such there are no OE related patches to apply. 
 
 
 
* There is no reason why you can't steal the OE kernel config, and apply it to the newer kernel.  See if you can figure out how to do this.  (Hint: You will need to combine both above links directions)
 
 
 
* Alternatively if you've previously built the kernel, take a peek in your ${OETREE}/downloads.  This is where the old kernel source (pre-patches) was downloaded, and see if you can manually apply the OE patches.
 
 
 
== Finding the Kernel to copy it ==
 
 
 
Once your compile has finished, where is uImage?  One way to find it is
 
 
 
<pre>
 
$ cd ~/BeagleBoard/oe
 
$ find . -name "*uImage*"
 
</pre>
 
You'll find several files with uImage in the name.  The one you want is
 
 
 
<pre>
 
$ cd ~/BeagleBoard/oe/build/tmp-angstrom_2008
 
$ ls
 
</pre>
 
 
 
Here you'll see several directories here.  If you <code>cd work</code> you will find the source code.  We are going to go this way.
 
<pre>
 
$ cd deploy/glibc
 
</pre>
 
 
 
Here you will find some more directories worth exploring.  What do you find in <code>sources</code>?  Finally
 
<pre>
 
$ cd images/beagleboard
 
</pre>
 
Now you have found uImage.  Load away.
 
 
 
== Here's what I did to create the files above ==
 
 
 
You don't have to do the following.  This is what I have already done.
 
 
 
Instructions for building Ångström are given [http://www.angstrom-distribution.org/building-angstrom here]; however there are a few changes you have to make.  Here's what I did. 
 
 
 
=== Get the setup scripts ===
 
 
 
I have everything in a <code>~/BeagleBoard</code>, so here is how I setup things:
 
<pre>
 
$ cd
 
$ mkdir -p BeagleBoard
 
$ cd BeagleBoard
 
$ git clone git://git.angstrom-distribution.org/setup-scripts oe
 
$ cd oe
 
</pre>
 
This creates a directory for open embedded (<code>oe</code>) and gets the script to download Ångström.  What files do you see?
 
 
 
Edit <code>oebb.sh</code> and replace every place you find
 
 
 
<pre>
 
git://git.openembedded.org/openembedded
 
</pre>
 
 
 
with
 
 
 
<pre>
 
git://git.openembedded.org/openembedded.git
 
</pre>
 
 
 
Also replace
 
 
 
<pre>
 
INHERIT += "rm_work"
 
</pre>
 
 
 
with
 
<pre>
 
# INHERIT += "rm_work"
 
</pre>
 
 
 
Save the file and then run
 
 
 
<pre>
 
MACHINE=beagleboard ./oebb.sh update
 
</pre>
 
This will bring in all the tools you need.  It took about 30 minutes on my machine in the afternoon or 3 minutes at 6:15am.
 
 
 
=== Point to the git snapshot that was used to create the image ===
 
 
 
The original SD card image came from [http://beagleboard-validation.s3.amazonaws.com/deploy/201008201549/sd/list.html here].  The file [http://beagleboard-validation.s3.amazonaws.com/deploy/201008201549/sd/ec2build.sh ec2buld.sh] shows how the image was build.  There are a couple of interesting things in this file. 
 
 
 
Line 564 shows an additional git repository was used.
 
 
 
<pre>
 
$ cd sources/openembedded
 
$ git remote add myrepo git://gitorious.org/~Jadon/angstrom/jadon-openembedded.git
 
$ git remote update
 
</pre>
 
 
 
Run this git command to get access to this repository.  Line 21 shows the hash tag for the build.
 
 
 
<pre>
 
ANGSTROM_REPO_ID=24805033b1205acc35f8b4d75cc42f8b9c2a1b38
 
</pre>
 
 
 
If we pull from this tag we will have the same files as were used to generate the SD image.  So do the following
 
 
 
<pre>
 
git checkout 24805033b1205acc35f8b4d75cc42f8b9c2a1b38
 
</pre>
 
 
 
=== Compile the Kernel ===
 
 
 
Now if you do
 
 
 
<pre>
 
$ source ~/.oe/enviroment-2008
 
$ bitbake linux-omap-psp-2.6.32
 
</pre>
 
you should get a kernel that will work.
 
 
 
To ensure you keep the kernel source, check your .../oe/build/conf/local.conf and comment out the line that says
 
<pre>
 
INHERIT += "rm_work"
 
</pre>
 
If you accidentally run bitbake without commenting out the above line, after it runs you can comment out the INHERIT line and then run
 
<pre>
 
$ bitbake -c clean linux-omap-psp-2.6.32
 
$ bitbake -f -c compile linux-omap-psp-2.6.32
 
</pre>
 
This second run should take less time (one timing: first run took 3.5 hours; the recompiling took 25 minutes).
 
 
 
Note from Joel:
 
I had to run
 
<pre>
 
$ ./oebb.sh config beagleboard
 
</pre>
 
at some point before the bitbake command would run for me.
 

Revision as of 06:14, 28 September 2017

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 32-bit LSB executable, Intel 80386, version 1 (SYSV), 
 dynamically linked (uses shared libs), for GNU/Linux 2.6.24, 
 BuildID[sha1]=0x357e34e90f7c32d414368d69cc06d0aed59acf1c, not stripped
host$ ./a.out
Hello, World! Main is executing at 0x400524
This address (0x7fff8260bdf8) is in our stack frame
This address (0x601038) is in our bss section
This address (0x601020) 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-linaro-5.4.1-2017.05-x86_64_arm-linux-gnueabihf
gcc-linaro-5.4.1-2017.05-x86_64_arm-linux-gnueabihf.tar.xz
gcc-linaro-7.1.1-2017.08-x86_64_arm-linux-gnueabihf
gcc-linaro-7.1.1-2017.08-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-linaro-7.1.1-2017.08-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 (uses shared libs), for GNU/Linux 2.6.32, 
 BuildID[sha1]=b9222cbcee442470c7b89ac294e392a631c82264, 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 0x8374
This address (0xbeb32d4c) is in our stack frame
This address (0x10650) is in our bss section
This address (0x10648) 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