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

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m (Cross compiling Hello World: Updated for new compiler version. Switched from root to debian)
m (Cross compiling Hello World: Updated compiler path)
 
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Line 12: Line 12:
 
  host$ '''gcc helloWorld.c'''
 
  host$ '''gcc helloWorld.c'''
 
  host$ '''file a.out'''
 
  host$ '''file a.out'''
  a.out: ELF 32-bit LSB executable, Intel 80386, version 1 (SYSV),  
+
  a.out: ELF 64-bit LSB shared object, x86-64, version 1 (SYSV), dynamically linked,
  dynamically linked (uses shared libs), for GNU/Linux 2.6.24,  
+
interpreter /lib64/ld-linux-x86-64.so.2, for GNU/Linux 3.2.0,
  BuildID[sha1]=0x357e34e90f7c32d414368d69cc06d0aed59acf1c, not stripped
+
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 figure out what version of the cross compiler was loaded.
Line 25: Line 25:
 
  host$ '''cd BeagleBoard/bb-kernel/dl'''
 
  host$ '''cd BeagleBoard/bb-kernel/dl'''
 
  host$ '''ls'''
 
  host$ '''ls'''
  gcc-linaro-5.4.1-2017.05-x86_64_arm-linux-gnueabihf
+
  gcc-arm-8.3-2019.03-x86_64-arm-linux-gnueabihf
gcc-linaro-5.4.1-2017.05-x86_64_arm-linux-gnueabihf.tar.xz
+
  gcc-arm-8.3-2019.03-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.
 
Here we see two versions of the compiler have been loaded.  Let's pick the newer one.
Line 36: Line 34:
 
  export ARCH=arm
 
  export ARCH=arm
 
  export CROSS_COMPILE=arm-linux-gnueabihf-
 
  export CROSS_COMPILE=arm-linux-gnueabihf-
  export PATH=$PATH:~/BeagleBoard/bb-kernel/dl/gcc-linaro-7.1.1-2017.08-x86_64_arm-linux-gnueabihf/bin
+
  export PATH=$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.
 
Make sure the PATH you use goes to the bin directory where the cross compiler is installed.
  
Line 43: Line 42:
 
  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, EABI5 version 1 (SYSV),  
+
  a.out: ELF 32-bit LSB executable, ARM, EABI5 version 1 (SYSV),
  dynamically linked (uses shared libs), for GNU/Linux 2.6.32,  
+
dynamically linked, interpreter /lib/ld-linux-armhf.so.3,
  BuildID[sha1]=b9222cbcee442470c7b89ac294e392a631c82264, not stripped
+
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
Line 51: Line 51:
 
  host$ '''scp a.out debian@192.168.7.2:.'''
 
  host$ '''scp a.out debian@192.168.7.2:.'''
 
  host$ '''ssh debian@192.168.7.2 ./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 addresses 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 addresses are very different from the host version.
  
 
{{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