YAACCT, Yet Another Aarch64 Cross-Compiler Toolchain.
Yes, you might ask yourself why you fall again on another aarch64-non-elf cross-compiler. Well, i had a need to build code for an aarch64 cpu running baremetal from my development PC with x86_64. I also need a lesser standard C library, so the choice fall for newlib.
My development PC use a standard Linux Distro (Fedora). And also, i was starting from scratch. I followed a lot of tutorials only to realized they don't work for my case. A lot of them consider you are already running with newlib from your build host. What about it is not?
That was my case!
So, here is my reminder for myself and everyone finding it.
My article will try to cover the steps starting from your base distro, to a 2 stage cross compiler building, to finally be able to cross-compile for target aarch64-none-elf with newlib from a x86_64 build host.
The native distro gcc will be your bootstrap compiler and the native distro glibc will be the stage 1 library. Than, we will build binutils cross x86_64<->aarch64 to make the stage 1 compiler. Next we will build the stage 2 newlib library and finally build the stage 2 compiler with the help of the stage 1 compiler and stage 2 newlib.
A complete from scratch toolchain as the following steps :
-
- make linker and assembler for your host build
-
- make a bootstrap compiler
-
- make stage 1 library for headers
-
- make linker and assembler for your target
-
- make stage 1 cross-compiler
-
- make stage 2 cross-library for libs and headers
-
- make stage 2 cross-compiler.
- make stage 2 cross-compiler.
Since we need a toolchain from scratch but starting from an official distro, steps 1 to 3 are already make! :)
All stage 2 resources are what you need to cross-compile sources code from your host build machine to your target.
Additionnally, each cross build output give you tools for your host build architecture and your target architecture.
So, instead of a three entities toolchain: build machine - host machine - target machine, we have a two entities toolchain : build and host machine - target machine.
To initially follow my architecture :
- fedora 40, kernel 6.8.5-301
- "build-essential" from official repo with package manager (dnf):
sudo dnf install @development-tools - libtool from official repo with package manager (dnf):
sudo dnf install libtool - glibc multilib from official repo with package manager (dnf):
sudo dnf install glibc-devel glibc-static libstdc++-devel libstdc++-static
~/cross-compiler
|
|----sources
|
|----host-tools
|
|----build
Change directory to the sources directory.
For this toolchain, we will need : binutils, gcc, gmp, isl, expat, mpfr, mpc and newlib.
I like to download sources with wget! :)
wget https://ftp.gnu.org/gnu/binutils/binutils-2.44.tar.xz
wget https://ftp.gnu.org/gnu/gcc/gcc-14.2.0/gcc-14.2.0.tar.xz
wget https://ftp.gnu.org/gnu/gmp/gmp-6.3.0.tar.xz
wget https://repo.or.cz/isl.git/snapshot/80035e4c3fcbebf13a70752111f03d48a5e46dda.tar.gz
wget https://github.com/libexpat/libexpat/releases/download/R_2_7_1/expat-2.7.1.tar.gz
wget https://ftp.gnu.org/gnu/mpfr/mpfr-4.2.2.tar.xz
wget https://ftp.gnu.org/gnu/mpc/mpc-1.3.1.tar.gz
wget https://sourceware.org/pub/newlib/newlib-4.5.0.20241231.tar.gzExtract each source with tar -xf <name of the tarball with suffix>, add option z for .gz tarball.
Each tarball will add a new folder inside your sources directory with the name of the resource the archive contained.
Inside the folder of each resource, add a build folder for the configuration and building process.
~/cross-compiler
|
|----sources
| |
| |----binutils-*
| | |----build
| | |----*
| |
| |----gcc-*
| | |----build
| | |----*
| |
| |----<all others resources>-*
| |
| |----<all tarball>.tar.**
|
|----host-tools
|
|----build
Do note that in the follow step i use the home character ~, but each prefix must be an absolute path.
Change directory to the build directory of your GMP.
My configuration was : ../configure --disable-maintainer-mode --disable-shared --prefix=~/cross-compiler/host-tools --host=x86_64-none-linux-gnu
Than build : make -j$(nproc) && make install && make distclean && rm -rf config.cache
GMP will be install in the host-tools directory of the toolchain.
Change directory to the build directory of your MPFR.
My configuration was : ../configure --disable-maintainer-mode --disable-shared --prefix=~/cross-compiler/host-tools --with-gmp=~/cross-compiler/host-tools
Than build : make -j$(nproc) && make install && make distclean && rm -rf config.cache
MPFR will be install in the host-tools directory of the toolchain.
Change directory to the build directory of your MPC.
My configuration was : ../configure --disable-maintainer-mode --disable-shared --prefix=~/cross-compiler/host-tools --with-gmp=~/cross-compiler/host-tools --with-mpfr=~/cross-compiler/host-tools
Than build : make -j$(nproc) && make install && make distclean && rm -rf config.cache
MPC will be install in the host-tools directory of the toolchain.
Change directory to the root extracted folder of ISL. ISL probably need you to run his autogen script : ./autogen.sh
Additionnaly, i had to add a flag (LT_INIT) in the configure.ac script initialization section.
It is possible you have to run aclocal && autoconf && automake --add-missing
Change directory to the build directory of your ISL.
My configuration was : ../configure -disable-maintainer-mode --disable-shared --prefix=~/cross-compiler/host-tools --with-gmp-prefix=~/cross-compiler/host-tools
Than build : make -j$(nproc) && make install && make distclean && rm -rf config.cache
ISL will be install in the host-tools directory of the toolchain.
Change directory to the build directory of your BINUTILS.
My configuration was : -enable-64-bit-bfd --enable-targets=arm-none-eabi,aarch64-none-linux-gnu,aarch64-none-elf --enable-initfini-array --disable-nls --without-x --disable-gdbtk --without-tcl --without-tk --enable-plugins --disable-gdb --without-gdb --target=aarch64-none-elf --prefix=~/cross-compiler/build --with-bugurl="JohnDoe" --with-sysroot=~/cross-compiler/build/aarch64-none-elf --without-debuginfod
Than build : make -j$(nproc) && make install && make distclean && rm -rf config.cache
BINUTILS will be install in the build directory of the toolchain.
Before going any further, we need to update the PATH environment variable. Because from now on, you want to use the tools that you installed and that you will continue to install in your toolchain directory instead of using your native distro tools. So add the absolute path of the toolchain of your build host bin folder in your ~/.bashrc and update the variable. Add /home/path/to/the/cross-compiler/build/bin to your ~/.bashrc. And update source ~/.bashrc
Change directory to the build directory of your EXPAT.
My configuration was : --prefix=~/cross-compiler/host-tools --without-docbook --without-xmlwf
Than build : make -j$(nproc) && make install && make distclean && rm -rf config.cache
EXPAT will be install in the host-tools directory of the toolchain.
Change directory to the build directory of your GCC.
My configuration was : --with-gmp=~/cross-compiler/host-tools --with-mpfr=~/cross-compiler/host-tools --with-mpc=~/cross-compiler/host-tools --with-isl=~/cross-compiler/host-tools --target=aarch64-none-elf --prefix=~/cross-compiler/build --disable-shared --disable-nls --disable-threads --disable-tls --enable-checking=release --enable-languages=c --without-cloog --without-isl --without-headers --with-gnu-as --with-gnu-ld --with-bugurl="JohnDoe"
Than build : make -j$(nproc) all-gcc && make -j$(nproc) all-target-libgcc && make install-gcc && make install-target-libgcc && make distclean && rm -rf config.cache
GCC will be install in the build directory of the toolchain. Note 1 : i don't want threads support in my target, i will implement them. Note 2 : you will probably need to remove completely the sources root extracted directory of gcc and extract it again and make another build folder inside it. i'm pretty sure the make distclean don't remove everything and you will need fresh configuration for stage 2 later.
Change directory to the build directory of your NEWLIB.
My configuration was : --target=aarch64-none-elf --disable-newlib-supplied-syscalls --enable-newlib-retargetable-locking --enable-newlib-reent-check-verify --enable-newlib-io-long-long --enable-newlib-io-long-double --enable-newlib-io-c99-formats --enable-newlib-register-fini --enable-newlib-mb --prefix=~/cross-compiler/build --with-bugurl="JohnDoe"
Than build : make -j$(nproc) && make install && make distclean && rm -rf config.cache
NEWLIB will be install in the build directory of the toolchain.
Change directory to the build directory of your GCC.
My configuration was : -target=aarch64-none-elf --prefix=~/cross-compiler/build --with-gmp=~/cross-compiler/host-tools --with-mpfr=~/cross-compiler/host-tools --with-mpc=~/cross-compiler/host-tools --with-isl=~/cross-compiler/host-tools --disable-shared --disable-nls --disable-threads --disable-tls --enable-checking=release --enable-languages=c,c++,fortran --with-newlib --with-gnu-as --with-headers=yes --with-gnu-ld --with-native-system-header-dir=/usr/include --with-sysroot=~/cross-compiler/build/aarch64-none-elf --with-bugurl="JohnDoe"
Than build : make -j$(nproc) all-gcc && make -j$(nproc) all-target-libgcc && make install-gcc && make install-target-libgcc && make distclean && rm -rf config.cache
GCC will be install in the build directory of the toolchain.
Make a simple hello.c text file and compile with aarch64-none-elf-gcc hello.c -o hello.elf:
#include <stdio.h>
int main() {
printf("Hello, World!\n");
return 0;
}Damn, it failed! the compiler is crying. Yes, because we remove all syscalls OS dependencies. You will need to implement those functions before building NEWLIB. That's the fun part, its your architecture. What is happening is the cross-compiler trying to add syscalls function to allocate memory(_sbrk), exit process (_exit), position buffer cursor(_lseek), read(_read) and write(_write) with prinft from the string to the stdout(_isatty,_fstat) and close the file descriptor(_close). You can add option -nostartfiles to gcc to stop the linker of adding syscall function to jump in/out to the process and allocate memory. But it will fail again because of printf. You have two choice : 1. implement all newlib syscalls or 2. use inline assembly. Lets try with inline assembly :
#include <stdint.h>
int main() {
const char *message = "Hello, World!\n";
asm volatile (
"mov x0, 1;" // File descriptor 1 (stdout)
"mov x1, %0;" // Address of the message
"mov x2, 14;" // Length of the message (14 bytes)
"mov x8, 64;" // sys_write system call number (64)
"svc 0;" // Make the system call
:
: "r"(message) // Input: the message string
: "x0", "x1", "x2", "x8" // Clobbered registers
);
return 0;
}Compile and don't add process control : aarch64-none-elf-gcc hello.c -o hello.elf -nostartfiles
Boom! Compiled! Complete! Yes?
Well, no! You still make a syscall 64 with svc. So, i hope you have a supervior function that can manage this call or an OS. You now have 3 choices : 1. implement newlib syscall baremetal or OS API dependant 2. use inline assembly baremetal or OS API dependant 3. make an OS. The good news is the cross-compiler works! See you next time. ;) During this time, here is the proof of concept with a readelf -C hello.elf :
00000000 7f 45 4c 46 02 01 01 00 00 00 00 00 00 00 00 00 |.ELF............|
00000010 02 00 b7 00 01 00 00 00 00 00 40 00 00 00 00 00 |..........@.....|
00000020 40 00 00 00 00 00 00 00 a8 02 01 00 00 00 00 00 |@...............|
00000030 00 00 00 00 40 00 38 00 01 00 40 00 07 00 06 00 |....@.8...@.....|
00000040 01 00 00 00 05 00 00 00 00 00 01 00 00 00 00 00 |................|
00000050 00 00 40 00 00 00 00 00 00 00 40 00 00 00 00 00 |..@.......@.....|
00000060 47 00 00 00 00 00 00 00 47 00 00 00 00 00 00 00 |G.......G.......|
00000070 00 00 01 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00000080 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
00010000 ff 43 00 d1 00 00 00 90 00 e0 00 91 e0 07 00 f9 |.C..............|
00010010 e3 07 40 f9 20 00 80 d2 e1 03 03 aa c2 01 80 d2 |..@. ...........|
00010020 08 08 80 d2 01 00 00 d4 00 00 80 52 ff 43 00 91 |...........R.C..|
00010030 c0 03 5f d6 00 00 00 00 48 65 6c 6c 6f 2c 20 57 |.._.....Hello, W|
00010040 6f 72 6c 64 21 0a 00 47 43 43 3a 20 28 47 4e 55 |orld!..GCC: (GNU|
00010050 29 20 31 34 2e 32 2e 30 00 00 00 00 00 00 00 00 |) 14.2.0........|
00010060 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00010070 00 00 00 00 00 00 00 00 00 00 00 00 03 00 01 00 |................|
00010080 00 00 40 00 00 00 00 00 00 00 00 00 00 00 00 00 |..@.............|
00010090 00 00 00 00 03 00 02 00 38 00 40 00 00 00 00 00 |........8.@.....|
000100a0 00 00 00 00 00 00 00 00 00 00 00 00 03 00 03 00 |................|
000100b0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000100c0 01 00 00 00 04 00 f1 ff 00 00 00 00 00 00 00 00 |................|
000100d0 00 00 00 00 00 00 00 00 09 00 00 00 00 00 02 00 |................|
000100e0 38 00 40 00 00 00 00 00 00 00 00 00 00 00 00 00 |8.@.............|
000100f0 0c 00 00 00 00 00 01 00 00 00 40 00 00 00 00 00 |..........@.....|
00010100 00 00 00 00 00 00 00 00 1e 00 00 00 10 00 02 00 |................|
00010110 47 00 41 00 00 00 00 00 00 00 00 00 00 00 00 00 |G.A.............|
00010120 0f 00 00 00 10 00 02 00 47 00 41 00 00 00 00 00 |........G.A.....|
00010130 00 00 00 00 00 00 00 00 1d 00 00 00 10 00 02 00 |................|
00010140 47 00 41 00 00 00 00 00 00 00 00 00 00 00 00 00 |G.A.............|
00010150 5b 00 00 00 10 00 00 00 00 00 00 00 00 00 00 00 |[...............|
00010160 00 00 00 00 00 00 00 00 29 00 00 00 10 00 02 00 |........).......|
00010170 47 00 41 00 00 00 00 00 00 00 00 00 00 00 00 00 |G.A.............|
00010180 35 00 00 00 12 00 01 00 00 00 40 00 00 00 00 00 |5.........@.....|
00010190 34 00 00 00 00 00 00 00 3a 00 00 00 10 00 02 00 |4.......:.......|
000101a0 48 00 41 00 00 00 00 00 00 00 00 00 00 00 00 00 |H.A.............|
000101b0 42 00 00 00 10 00 02 00 47 00 41 00 00 00 00 00 |B.......G.A.....|
000101c0 00 00 00 00 00 00 00 00 49 00 00 00 10 00 02 00 |........I.......|
000101d0 48 00 41 00 00 00 00 00 00 00 00 00 00 00 00 00 |H.A.............|
000101e0 4e 00 00 00 10 00 02 00 00 00 08 00 00 00 00 00 |N...............|
000101f0 00 00 00 00 00 00 00 00 55 00 00 00 10 00 02 00 |........U.......|
00010200 47 00 41 00 00 00 00 00 00 00 00 00 00 00 00 00 |G.A.............|
00010210 00 68 65 6c 6c 6f 2e 63 00 24 64 00 24 78 00 5f |.hello.c.$d.$x._|
00010220 5f 62 73 73 5f 73 74 61 72 74 5f 5f 00 5f 5f 62 |_bss_start__.__b|
00010230 73 73 5f 65 6e 64 5f 5f 00 5f 5f 62 73 73 5f 73 |ss_end__.__bss_s|
00010240 74 61 72 74 00 6d 61 69 6e 00 5f 5f 65 6e 64 5f |tart.main.__end_|
00010250 5f 00 5f 65 64 61 74 61 00 5f 65 6e 64 00 5f 73 |_._edata._end._s|
00010260 74 61 63 6b 00 5f 5f 64 61 74 61 5f 73 74 61 72 |tack.__data_star|
00010270 74 00 00 2e 73 79 6d 74 61 62 00 2e 73 74 72 74 |t...symtab..strt|
00010280 61 62 00 2e 73 68 73 74 72 74 61 62 00 2e 74 65 |ab..shstrtab..te|
00010290 78 74 00 2e 72 6f 64 61 74 61 00 2e 63 6f 6d 6d |xt..rodata..comm|
000102a0 65 6e 74 00 00 00 00 00 00 00 00 00 00 00 00 00 |ent.............|
000102b0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
*
000102e0 00 00 00 00 00 00 00 00 1b 00 00 00 01 00 00 00 |................|
000102f0 06 00 00 00 00 00 00 00 00 00 40 00 00 00 00 00 |..........@.....|
00010300 00 00 01 00 00 00 00 00 34 00 00 00 00 00 00 00 |........4.......|
00010310 00 00 00 00 00 00 00 00 04 00 00 00 00 00 00 00 |................|
00010320 00 00 00 00 00 00 00 00 21 00 00 00 01 00 00 00 |........!.......|
00010330 02 00 00 00 00 00 00 00 38 00 40 00 00 00 00 00 |........8.@.....|
00010340 38 00 01 00 00 00 00 00 0f 00 00 00 00 00 00 00 |8...............|
00010350 00 00 00 00 00 00 00 00 08 00 00 00 00 00 00 00 |................|
00010360 00 00 00 00 00 00 00 00 29 00 00 00 01 00 00 00 |........).......|
00010370 30 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |0...............|
00010380 47 00 01 00 00 00 00 00 12 00 00 00 00 00 00 00 |G...............|
00010390 00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00 |................|
000103a0 01 00 00 00 00 00 00 00 01 00 00 00 02 00 00 00 |................|
000103b0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
000103c0 60 00 01 00 00 00 00 00 b0 01 00 00 00 00 00 00 |`...............|
000103d0 05 00 00 00 07 00 00 00 08 00 00 00 00 00 00 00 |................|
000103e0 18 00 00 00 00 00 00 00 09 00 00 00 03 00 00 00 |................|
000103f0 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00010400 10 02 01 00 00 00 00 00 62 00 00 00 00 00 00 00 |........b.......|
00010410 00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00 |................|
00010420 00 00 00 00 00 00 00 00 11 00 00 00 03 00 00 00 |................|
00010430 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |................|
00010440 72 02 01 00 00 00 00 00 32 00 00 00 00 00 00 00 |r.......2.......|
00010450 00 00 00 00 00 00 00 00 01 00 00 00 00 00 00 00 |................|
00010460 00 00 00 00 00 00 00 00 |........|
00010468