Building ARM ELF EABI--Step by Step

Someone ask why not download binaries from CodeSourcery instead of compile it. The answer is that, yes, apparently, the lite edition toolchain is lack of functionality and lack of sufficient libraries support. Besides, compiling from scratch can also help us for understanding the whole structure of compiler system.   My workstation is equipped with Ubuntu and before our work, following packages should be installed(those packages are x86 architecture):

  mpfr, make, gmp, texinfo, texlive

  Now, first of all, download source package from CodeSourcery server, here is the website,

  http://www.codesourcery.com/gnu_toolchains/arm/portal/package3381/public/arm-none-eabi/arm-2008q3-39-arm-none-eabi.src.tar.bz2

  And then, unpack it to /home/embedded/arm-2008q3-39-arm-none-eabi/ and unpack following tarball. Updating PATH variable is also needed,

  tar -jxvf /home/embedded/arm-2008q3-39-arm-none-eabi/binutils-2008q3-39.tar.bz2
  tar -jxvf /home/embedded/arm-2008q3-39-arm-none-eabi/gcc-2008q3-39.tar.bz2
  tar -jxvf /home/embedded/arm-2008q3-39-arm-none-eabi/newlib-2008q3-39.tar.bz2
  export $PATH=/home/embedded/armelf/install/bin/:$PATH

  Now cd into binutils-stable and build it. Here are the configure scripts,
 
  ./configure --build=i686-pc-linux-gnu --target=arm-none-eabi --prefix=/home/embedded/armelf/install/ --host=i686-pc-linux-gnu --disable-nls --with-sysroot=/home/embedded/armelf/install/arm-none-eabi --enable-poison-system-directories

  make

  make install

 Next, build bootstrap GCC,

  ../source/gcc-4.3/configure --build=i686-pc-linux-gnu --host=i686-pc-linux-gnu --target=arm-none-eabi --enable-threads --disable-libmudflap --disable-libssp --disable-libstdcxx-pch --with-gnu-as --with-gnu-ld --enable-languages=c,c++ --disable-shared --with-newlib --prefix=/home/embedded/armelf/install/ --disable-shared --disable-threads --disable-libssp --disable-libgomp --without-headers --with-newlib --disable-decimal-float --disable-libffi --enable-languages=c --with-sysroot=/home/embedded/armelf/install/arm-none-eabi --disable-libgomp --enable-poison-system-directories --with-build-time-tools=/home/embedded/armelf/install/arm-none-eabi/bin/ --with-cpu=arm7tdmi

  make

  make install

  Newlib,

  ./configure --build=i686-pc-linux-gnu --target=arm-none-eabi --prefix=/home/embedded/armelf/install/ --host=i686-pc-linux-gnu --enable-newlib-io-long-long --disable-newlib-supplied-syscalls --disable-libgloss --disable-newlib-supplied-syscalls --disable-nls

  make

  make install

  and GCC Final,

  ../source/gcc-4.3/configure --build=i686-pc-linux-gnu --host=i686-pc-linux-gnu --target=arm-none-eabi --enable-threads --disable-libmudflap --disable-libssp --disable-libstdcxx-pch --with-gnu-as --with-gnu-ld --enable-languages=c,c++ --disable-shared --with-newlib --prefix=/home/embedded/armelf/install/ --disable-libgomp --enable-poison-system-directories --with-build-time-tools=/home/embedded/armelf/install/arm-none-eabi/bin/ --with-headers=/home/embedded/armelf/install/arm-none-eabi/include/ --with-libs="/home/embedded/armelf/install/arm-none-eabi/lib/" --with-cpu=arm7tdmi

  make

  make install

  Please pay attention to option "with-cpu" (where I mark those as red color). If you want to change the target architecture, you just change "arm7tdmi". The compiler will consider this option as default when you doesn't specify "-mcpu" using arm-gcc.

  Quite simple, isn't it? Now let's try some examples and see the results.

#include <math.h>
int main(int argc,char** argv)
{
    double a=1.33,b=2.44;
    double c;
    c=sin(a)+cos(b);
    return 0;
}

arm-none-eabi-gcc ./test.c -o test -lm

file ./test

./test: ELF 32-bit LSB executable, ARM, version 1 (SYSV), statically linked, not stripped

arm-none-eabi-readelf -h ./test #Display header section

ELF Header:
Magic:   7f 45 4c 46 01 01 01 00 00 00 00 00 00 00 00 00
Class:                             ELF32
Data:                              2's complement, little endian
Version:                           1 (current)
OS/ABI:                            UNIX - System V
ABI Version:                       0
Type:                              EXEC (Executable file)
Machine:                           ARM
Version:                           0x1
Entry point address:               0x8018
Start of program headers:          52 (bytes into file)
Start of section headers:          64780 (bytes into file)
Flags:                             0x5000002, has entry point, Version5 EABI
Size of this header:               52 (bytes)
Size of program headers:           32 (bytes)
Number of program headers:         2
Size of section headers:           40 (bytes)
Number of section headers:         25
Section header string table index: 22

arm-none-eabi-readelf -A ./test #Display architecture specific information

Attribute Section: aeabi
File Attributes
Tag_CPU_name: "ARM7TDMI"
Tag_CPU_arch: v4T
Tag_ARM_ISA_use: Yes
Tag_ABI_PCS_wchar_t: 4
Tag_ABI_FP_denormal: Needed
Tag_ABI_FP_exceptions: Needed
Tag_ABI_FP_number_model: IEEE 754
Tag_ABI_align8_needed: Yes
Tag_ABI_align8_preserved: Yes, except leaf SP
Tag_ABI_enum_size: small

  The simplest way to investigate program ABI is that, ARM-GCC without EABI support will show "GNU EABI" instead of "Version5 EABI" in "Flags" option when you using arm-readelf.

  And once more, ARM-ELF-EABI is not used for compiling binaries running on top of Linux. You can see the warning information like "No Entry Point" when you compile it. When you want to rich the libary set, "prefix" option in configure stage should be /home/embedded/armelf/install/arm-none-eabi