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In thisThis tutorial wefocuses willon createcreating a GCC cross-compiler for your own operating system. This compiler isthat speciallywe madebuild tohere targetwill exactlyhave youra operatinggeneric systemtarget and(i686-elf) is whatthat allows you to leave the current operating system behind, meaning that no headers or libraries of the host operating system will be used. YouWithout ''need''using a cross-compiler for operating systemssystem development, unlessa youlot areof developingunexpected things can happen because the compiler assumes that the code is running on yourthe ownhost operating system.
 
== Introduction ==
 
Generally speaking, a cross-compiler is a compiler that runs on platform A (the '''host'''), but generates executables for platform B (the '''target'''). These two platforms may (but do not need to) differ in CPU, operating system, and/or [[:Category:Executable Formats|executable format]]. In our case, the host platform is your current operating system, and the target platform is the operating system you are about to make. It is important to realize that these two platforms are not the same; yourthe operating system you are developing is always going to be different from your currentthe operating system. This is why we need to build a cross-compiler first, you will most certainly run into troublecurrently otherwiseuse.
 
=== Why docross-compilers Iare need a Cross Compiler?necessary ===
{{Main|Why do I need a Cross Compiler?}}
 
You need to use a cross-compiler ''unless'' you are developing on your own operating system. The compiler must know the correct target platform (CPU, operating system), otherwise you will run into trouble. If you use theThe compiler that comes with yourthe host system, thendoes thenot compilerknow won'tby knowdefault that it is compiling something else entirely., Some tutorials suggest using your system compiler and passingunless a lot of problematic options are passed to theit, compiler. Thiswhich will certainly give youcreate a lot of problems in the future. and theThe solution is build a cross-compiler. If you have already attempted to make an operating system without usingbuild a cross-compiler, please read the article [[Why do I need a Cross Compiler?]].
 
=== Which compiler version doto I want?choose ===
{{Main|Building GCC}}
 
The newest [[GCC]] is recommended as it is the latest and greatest release. However, it is recommended that you use the same major compiler version to build your cross-compiler. For instance, youusing may run into trouble if you use gccGCC 4.6.3 to build a gccGCC 4.8.0 cross-compiler. Ifwould youcreate aretroubles. notHere usingis thehow latest major GCC release for your system compiler, we recommend that youto [[Building GCC|build the newest GCC as your system compiler]].
 
You can also use older releases as they are usually reasonably good. If your local system compiler isn't too terribly old (at least gccGCC 4.6.0), you may wish to save yourself the trouble and just pick the latest minor release (such as 4.6.3 if your system compiler is 4.6.1) for your cross-compiler.
 
YouThis cancommand viewprints yourthe current compiler version by invoking:
 
<sourcesyntaxhighlight lang="bash">gcc --version</source>
gcc --version
</syntaxhighlight>
 
You may be able to use an older major GCC release to build a cross-compiler of a newer major GCC releaserrelease. For instance, gccGCC 4.7.3 may be able to build a gccGCC 4.8.0 cross-compiler. However, if you want to use the latest and greatest gccGCC version for your cross-compiler, we recommend that you [[Building GCC|bootstrap the newest gccGCC]] as your system compiler first. MacIndividuals using OS X will10.7 ''mostor certainly''earlier wishmight want to doinvest so,in aseither newerbuilding Maca OSsystem XGCC versions(that doesn'toutputs shipnative GCCMach-O), ator all,upgrading the local LLVM/Clang installation. Users with 10.8 and othersabove onlyshould shipinstall athe veryCommand oldLine versionTools from Apple's developer website and use Clang to cross-compile GCC.
 
=== Which binutils version doto I want?choose ===
{{Main|Cross-Compiler Successful Builds}}
We recommend that you use theThe latest and greatest binutils[[Binutils]] release is recommended. Note, however, that not all combinations of GCC and binutilsBinutils work. If you run into trouble, use a binutilsBinutils that was released at roughly the same time as your desired compiler version. You probably need at least binutilsBinutils 2.22, or preferably the latest 2.23.2 release. It doesn't matter what binutilsBinutils version you have installed on your current operating system. This command prints the binutils version:
<syntaxhighlight lang="bash">
ld --version
</syntaxhighlight>
 
=== Deciding on the target platform ===
Line 32 ⟶ 38:
 
You should already know this. If you are following the [[Bare Bones]] tutorial, you wish to build a cross-compiler for <tt>i686-elf</tt>.
 
=== Note on arm-none-eabi-gcc ===
There is the prebuilt package gcc-arm-none-eabi on apt-get for Debian/Ubuntu, but you shouldn't use it because it neither contains a libgcc.a nor freestanding C header files like stdint.h.<br>
Instead you should build it yourself with <tt>arm-none-eabi</tt> being the $TARGET.
 
== Preparing for the build ==
Line 47 ⟶ 57:
=== Preparation ===
 
<sourcesyntaxhighlight lang="bash">
export PREFIX="$HOME/opt/cross"
export TARGET=i686-none-elf
export PATH="$PREFIX/bin:$PATH"
</syntaxhighlight>
</source>
 
We add the installation prefix to the <tt>PATH</tt> of the current shell session. This ensures that the compiler build is able to detect our new binutils once we have built them.
Line 58 ⟶ 68:
 
=== Binutils ===
<!--
 
This confuses some people a bit too much and they should just get it through package management and follow the above instructions.
<source lang="bash">
# If you wish to build these packages as part of binutils:
mv isl-x.y.z binutils-x.y.z/isl
mv cloog-x.y.z binutils-x.y.z/cloog
# But reconsider: You should just get the development packages from your OS.
-->
<syntaxhighlight lang="bash">
cd $HOME/src
 
mkdir build-binutils
cd build-binutils
../binutils-x.y.z/configure --target=$TARGET --prefix="$PREFIX" --with-sysroot --disable-nls --disable-werror
make
make install
</syntaxhighlight>
</source>
 
This compiles the binutils (assembler, disassembler, and various other useful stuff), runnable on your system but handling code in the format specified by $TARGET.
 
'''--disable-nls''' tells binutils not to include native language support. This is basically optional, but reduces dependencies and compile time. It will also result in English-language diagnostics, which the people on the [http://forum.osdev.org/ Forum] understand when you ask your questions. ;-)
 
'''--with-sysroot''' tells binutils to enable sysroot support in the cross-compiler by pointing it to a default empty directory. By default, the linker refuses to use sysroots for no good technical reason, while gcc is able to handle both cases at runtime. This will be useful later on.
 
=== GDB ===
 
It may be worth noting that if you wish to use '''GDB''', and you are running on a different computer architecture than your OS (most common case is developing for ARM on x86_64 or x86_64 on ARM), you need to cross-compile GDB separately. While technically a part of Binutils, it resides in a separate repository.
 
The protocol for building GDB to target a different architecture is very similar to that of regular Binutils:
 
<syntaxhighlight lang="bash">
../gdb.x.y.z/configure --target=$TARGET --prefix="$PREFIX" --disable-werror
make all-gdb
make install-gdb
</syntaxhighlight>
 
The <tt>'''--disable-nls'''</tt> and <tt>'''--with-sysroot'''</tt> options don't seem to have any effect.
 
=== GCC ===
Line 76 ⟶ 109:
 
Now, you can build [[GCC]].
<!--
 
This confuses some people a bit too much and they should just get it through package management and follow the above instructions.
<source lang="bash">
cd $HOME/src
 
# If you wish to build these packages as part of gcc:
mv libiconv-x.y.z gcc-x.y.z/libiconv # Mac OS X users
Line 85 ⟶ 116:
mv mpfr-x.y.z gcc-x.y.z/mpfr
mv mpc-x.y.z gcc-x.y.z/mpc
mv isl-x.y.z gcc-x.y.z/isl
mv cloog-x.y.z gcc-x.y.z/cloog
# But reconsider: You should just get the development packages from your OS.
-->
 
<syntaxhighlight lang="bash">
cd $HOME/src
 
# The $PREFIX/bin dir _must_ be in the PATH. We did that above.
which -- $TARGET-as || echo $TARGET-as is not in the PATH
 
mkdir build-gcc
Line 93 ⟶ 134:
make install-gcc
make install-target-libgcc
</syntaxhighlight>
</source>
 
We build [[libgcc]], a low-level support library that the compiler expects available at compile time. Linking against [[libgcc]] provides integer, floating point, decimal, stack unwinding (useful for exception handling) and other support functions. Note how we are ''not'' simply running <tt>make && make install</tt> as that would build way too much, not all components of gcc isare ready to target your unfinished operating system.
 
'''--disable-nls''' is the same as for binutils above.
Line 103 ⟶ 144:
'''--enable-languages''' tells [[GCC]] not to compile all the other language frontends it supports, but only C (and optionally C++).
 
It will take a while to build your cross-compiler. On a multi-core machine, speed up the build by parallelizing it, e.g. <tt>make -j 8 all-gcc</tt>, if 8 is the number of jobs to run simultaneously.
 
If you are building a cross compiler for x86-64, you may want to consider building Libgcc without the "red zone": [[Libgcc_without_red_zone]]
 
== Using the new Compiler ==
 
Now you have a "naked" cross-compiler. It does not have access to a C library or C runtime yet, so you cannot use anymost of the standard includes or create runnable binaries. But it is quite sufficient to compile the kernel you will be making shortly. Your toolset resides in $HOME/opt/cross (or what you set <tt>$PREFIX</tt> to). For example, you have a gccGCC executable installed as <tt>$HOME/opt/cross/bin/$TARGET-gcc</tt>, which creates programs for your TARGET.
 
You can now run your new compiler by invoking something like:
 
<syntaxhighlight lang="bash">
<source lang="bash">$HOME/opt/cross/bin/$TARGET-gcc --version</source>
$HOME/opt/cross/bin/$TARGET-gcc --version
</syntaxhighlight>
 
Note how this compiler is ''not'' able to compile normal C programs. The cross-compiler will spit errors whenever you want to #include any of the standard headers (except for a select few that actually are platform-independent, and generated by the compiler itself). This is quite correct - you don't have a standard library for the target system yet!
 
The C standard defines two different kinds of executing environments - "freestanding" and "hosted". While the definition might be rather fuzzy for the average application programmer, it is pretty clear-cut when you're doing OS development: A kernel is "freestanding", everything you do in user space is "hosted". A "freestanding" environment needs to provide only a subset of the C library: <tt>float.h</tt>, <tt>iso646.h</tt>, <tt>limits.h</tt>, <tt>stdalign.h</tt>, <tt>stdarg.h</tt>, <tt>stdbool.h</tt>, <tt>stddef.h</tt>, <tt>stdint.h</tt> and stdint<tt>stdnoreturn.h</tt> (as of C99C11). All of these consist of typedef s and #define s "only", so you can implement them without a single .c file in sight.
 
Note that to have these compiler-provided includes work properly, you need to build your kernel with the <tt>-ffreestanding</tt> flag. Otherwise, they might attempt including your standard library's copy of the headers, which isn't gonna work if you don't have a standard library.
 
To use your new compiler simply by invoking <tt>$TARGET-gcc</tt>, add <tt>$HOME/opt/cross/bin</tt> to your <tt>$PATH</tt> by typing:
 
<syntaxhighlight lang="bash">
<source lang="bash">export PATH="$HOME/opt/cross/bin:$PATH"</source>
export PATH="$HOME/opt/cross/bin:$PATH"
</syntaxhighlight>
 
This command will add your new compiler to your PATH for this shell session. If you wish to use it permanently, add the PATH command to your <tt>~/.profile</tt> configuration shell script or similar. Consult your shell documentation for more information.
Line 127 ⟶ 176:
== Troubleshooting ==
 
In general, '''verify''' that you typedread the "make"instructions carefully and typed the commands precisely. IfDon't skip instructions. You will have to set your shellPATH crashesvariable duringagain if you use a "make"new shell instance, if ''you needdon't tomake re-enterit anypermanent PATHby export''adding it beforeto runningyour "make"shell againprofile. If a compilation seems to have gotten really messed up, type "<tt>make clean"distclean</tt>, and then start the make process over again. (butEnsure youyour probablyun-archiever dodoesn't not need tochange rerunnewline "configure")characters.
 
==== ld: cannot find -lgcc ====
'''line 11: $'\r': command not found'''
 
You specified that you want to link the GCC low-level runtime library into your executable through the <tt>-lgcc</tt>' switch, but forgot to build and properly install the library.<br>
You unpacked the source with WinZIP or something else that converts all text files to the Windows CRLF format. Use 7-Zip or the Cygwin tar program (tar xjf packagename.tar.bz2) to do your unpacking.
If you got no warnings or errors while installing libgcc and you still have problems you can copy the library in your project and link it with <tt>-L. -lgcc</tt><br>
The libgcc is at $PREFIX/lib/gcc/$TARGET/<gcc-version>/libgcc.a .
 
==== Binutils 2.9 ====
Note: On some browsers, when you download a "tarball" that ends in ".tar.bz2", your browser may rename it to ".tar.tar" -- don't worry, it will still work, just rename it back to ".tar.bz2".
 
What's alphabetically on the top or bottom is not necessarily the latest version. After 2.9 comes 2.10, 2.11, 2.12 and then there are more releases that are all newer and progressively more likely to build or support your choice of GCC version.
'''i686-elf-ar not found'''
 
==== Building GCC: the directory that should contain system headers does not exist ====
You forgot to set the executable path ($PATH) to include $PREFIX/bin.
 
You might encounter this error when building <tt>mingw32</tt> targets, for example <tt>x86_64-w64-mingw32</tt>. The offending directory that can't be found is <tt>$SYSROOT/mingw/include</tt>. If you look in your sysroot, you will, of course, realise that no such folder exists.
'''Error: junk at end of line, first unrecognized character is ',' '''
 
The solution is simply to create the empty folders:
This, in combination with lots of other assembly-level error messages (like, ''Warning: .type pseudo-op used outside of .def/.endef ignored'', or ''Error: unknown pseudo-op: '.local' '') results when you did not correctly set the --prefix=$PREFIX during the binutils configure.
<syntaxhighlight lang="bash">
mkdir -p $SYSROOT/mingw/include
mkdir -p $SYSROOT/mingw/lib
</syntaxhighlight>
 
This will allow the build to proceed. The reason this happens is that the <tt>mingw32</tt> (and mingw itself) configures <tt>INCLUDE_PATH</tt> and <tt>LIBRARY_PATH</tt> to be, as can be guessed, <tt>/mingw/include</tt> and <tt>/mingw/lib</tt>, instead of the defaults <tt>/usr/include</tt> and <tt>/usr/lib</tt>. Why the build fails even though nothing is required in those folders, and why it doesn't just make them, is beyond me.
Another possibility is that you did configure, compile and install your cross-compiler correctly, but don't actually use it. Check the "Usage" section above.
 
=== GCC libsanitizer failing to build ===
:''If you try compiling in 64-bit windows, you will receive a "Unknown host machine type" error when running configure. To fix this, scroll up in your shell until right after you entered the configure command and you will see a website which will show you where to download updated files to guess host type. Put them in the root directory of where your source files are located. With [[GCC]] version 3.4.0 you will have to override the host environment though, as it does not support being compiled with x86_64-unknown-cygwin . Add the command line argument --host=i686-unknown-cygwin to the configure line for GCC. --[[User:CjMovie|CjMovie]] (Too many edits to get this right...)''
Sometimes GCC can't build libsanitizer, if that happens append <tt>--disable-libsanitizer</tt> to the configure command.<br>
This only applies for building a hosted compiler.
 
== More advanced ==
'''Configure: error: invalid feature name: nls'''
Using this simple cross compiler will be sufficient for quite some time, but at some point you will want the compiler to automatically include your own system headers and libraries. Building an [[OS Specific Toolchain|OS-specific toolchain]] for your own operating system is the way to go from here.
 
If you are using [[Cygwin]], it must be set to use Unix/binary as the file mode. You can set this by running setup.exe and selecting the appropriate mode.
 
'''*** Multiple patterns ...'''
 
This error can occur when you're using Cygwin (it could also occur on other instances). The most common cause is the cross-usage of UNIX-style paths and DOS-like paths (e.g. /usr/src and C:\MyFolder). If you were using a custom directory (e.g. C:\Cross-Compiler) to build the cross-compiler instead of the /usr/src directory, usually using the default folders (/usr/src, /usr/...) fixes these problems.
 
'''But I'm using Cygwin on Windows and I don't have any $HOME/src folder on my hard-drive!'''
 
If you didn't notice, Cygwin is a tool that works on Windows but acts UNIX-like, so if you run the 'Cygwin.bat' file in your Cygwin folder, you will get the BASH shell. If you snoop around in your Cygwin folder, you'll see a '''usr''' folder with a '''src''' folder inside (these folders will be used by Cygwin if you follow this tutorial).
 
'''C++ preprocessor "/lib/cpp" fails sanity check in Cygwin'''
 
In Cygwin's installer, you need to separately select the gcc4-core and gcc4-g++ packages for proper configuration of the host compiler.
 
'''ld: cannot find -lgcc'''
 
You specified that you want to link the GCC low-level runtime library into your executable through the ''-lgcc'' switch, but forgot build and properly install the library.
 
== See Also ==
=== Articles ===
*[[Boomstick]] a script to build a complete GCC toolchain, including newlib, for your OS.
*[[Canadian Cross]] - making things yet more complicated.
*[[Cross-Compiler Successful Builds]] - combinations of GCC and Binutils which have been shown to work with this tutorial by OSDev.org members.
*[[GCC Cross-Compiler on Linux]] - some distros make things much easier.
*[[Target Triplet]] - on target triplets and their use
*[[OS Specific Toolchain]] - going a step further and adding your own target.
*[[LLVM Cross-Compiler]] - some compilers make things much easier.
*[[Canadian Cross]] - making things yet more complicated.
 
=== External Links ===
Line 183 ⟶ 221:
*http://www.libsdl.org/extras/win32/cross/README.txt - dito
*https://github.com/travisg/toolchains - Another script for building simple cross compilers
*https://www.youtube.com/watch?v=aESwsmnA7Ec - A walkthrough of how to build a cross-compiler using Cygwin on Windows.
*https://github.com/Cheapskate01/Cross-Compiler-Build-Script - A dead-simple script that Binutils and Gcc for you.
 
[[Category:Compilers]]
Line 190 ⟶ 230:
=== Prebuilt Toolchains ===
These were built by people in the OSdev community for their own building needs and shared at will, without guaranteeing any support or that it will even work on your setup. YMMV.
 
'''Latests versions for Linux (many arch)'''
 
* [https://www.kernel.org/pub/tools/crosstool/ kernel.org various hosts/targets]
 
'''For Linux i686 host'''
* [https://drive.google.com/open?id=1zcFAmxi7mtOwhMaKE36IsjLRB0uEv17p aarch64-elf 9.3.0 target]
* [https://drive.google.com/open?id=1uEFrOJPxy13vxWCy-5IbxCJAs5TRdtTE arm-eabi 9.3.0 target]
* [https://drive.google.com/open?id=13Kg6Xd8acUnwUoZQBTOjwAQQeGOeYzVz i386-elf 9.3.0 target]
* [https://drive.google.com/open?id=1F5RsfIEfcpRYAqu5UuGTKgkMa3eBsXnP i486-elf 9.3.0 target]
* [https://drive.google.com/open?id=1PdEFqMEJf_Vuf0drO1m8bjlrsudAmI5k i586-elf 9.3.0 target]
* [https://drive.google.com/open?id=1g9jzEIn8CB6ZiVrc0uxbZprepcX4gYex i686-elf 9.3.0 target]
* [https://drive.google.com/open?id=1xIeNJwD0Do-REFxzCLOkMIVYI3HGJUTX mips-elf 9.3.0 target]
* [https://drive.google.com/open?id=10UuOf9LW4y9WEJcTWrMZW0GAlOWh9KG7 mips64-elf 9.3.0 target]
* [https://drive.google.com/open?id=1oW6UWr-OY22EgtyuXovORUtHeVLkL-Tw m64k-elf 9.3.0 target]
* [https://drive.google.com/open?id=1H3Cbq4D_kjROB-7Otiisa-mac_9FYUM- powerpc-elf 9.3.0 target]
* [https://drive.google.com/open?id=1kFGNHWhcBD9cf8X2y-BW49Su04lMa1ev sh-elf 9.3.0 target]
* [https://drive.google.com/open?id=1XzQDKTK35EX8b380bPRbuhX1GPKrtI77 sparc-elf 9.3.0 target]
* [https://drive.google.com/open?id=1pU8bS0McTyRUTHb1b_c8ZVa2Ka_XeeEp x86_64-elf 9.3.0 target]
* [https://drive.google.com/open?id=1cqk9RzY3QXQuaS-YdIWtCECKL81pcsv- xtensa-elf 9.3.0 target]
 
'''For Linux x86_64 host'''
 
* [https://drive.google.com/file/d/0Bw6lG3Ej2746STJaM2dNbC05elE/view?usp=sharing i386-elf & i686-elf 7.1.0 target uploaded by TheAlmostGenius]
* [http://newos.org/toolchains/i386-elf-4.9.0-Linux-x86_64.tar.xz i386-elf 4.9.0 target]
 
* [http://newos.org/toolchains/i686-elf-4.9.0-Linux-x86_64.tar.xz i686-elf 4.9.0 target]
* [httphttps://newos.org/toolchains/x86_64i386-elf-47.95.0-Linux-x86_64.tar.xz x86_64i386-elf 47.95.0 target]
* [httphttps://newos.org/toolchains/aarch64x86_64-elf-47.95.0-Linux-x86_64.tar.xz aarch64x86_64-elf 47.95.0 target]
* [httphttps://newos.org/toolchains/armaarch64-eabielf-47.95.0-Linux-x86_64.tar.xz armaarch64-eabielf 47.95.0 target for]
* [httphttps://newos.org/toolchains/m68karm-elfeabi-47.95.0-Linux-x86_64.tar.xz m68karm-elfeabi 47.95.0 target for]
* [httphttps://newos.org/toolchains/powerpcm68k-elf-47.95.0-Linux-x86_64.tar.xz powerpcm68k-elf 47.95.0 target]
* [httphttps://newos.org/toolchains/sparcmicroblaze-elf-47.95.0-Linux-x86_64.tar.xz sparcmicroblaze-elf 47.95.0 target]
* [httphttps://newos.org/toolchains/shmips-elf-47.85.10-Linux-x86_64.tar.xz shmips-elf 47.85.10 target]
* [https://newos.org/toolchains/nios2-elf-7.5.0-Linux-x86_64.tar.xz nios2-elf 7.5.0 target]
* [https://newos.org/toolchains/powerpc-elf-7.5.0-Linux-x86_64.tar.xz powerpc-elf 7.5.0 target]
* [https://newos.org/toolchains/riscv32-elf-7.5.0-Linux-x86_64.tar.xz riscv32-elf 7.5.0 target]
* [https://newos.org/toolchains/riscv64-elf-7.5.0-Linux-x86_64.tar.xz riscv64-elf 7.5.0 target]
* [https://newos.org/toolchains/sh-elf-7.5.0-Linux-x86_64.tar.xz sh-elf 7.5.0 target]
* [https://newos.org/toolchains/sparc-elf-7.5.0-Linux-x86_64.tar.xz sparc-elf 7.5.0 target]
 
The packages from phillid.tk below have been shrunk to about 10 MiB for each pair of packages (GCC &amp; Binutils).
Please note that this has been achieved by enabling only the C front-end for GCC.
If you're going to write your OS in any language but C or Assembly, these packages aren't for you.
These are actually Pacman packages, but untarring them to / and rm-ing /.MTREE and other clutter dotfiles contained in the package will work the same.
 
'''For Windows host'''
* [https://drive.google.com/file/d/0B85K_c7mx3QjUnZuaFRPWlBIcXM/edit?usp=sharing i686-elf 4.8.2 target]
* [https://mega.co.nz/#F!bBxA3SKJ!TDL4i1NjaZKd4YMo9p2U7g x86_64-elf 5.1.0 target]
* [https://github.com/lordmilko/i686-elf-tools i686-/x86_64-elf 13.2.0 target + GDB (Windows/Linux/WSL)]
 
'''For Windows Subsystem for Linux (Beta) host'''
* [http://www.bin-os.com/i686-elf-6.1.0.tar.gz i686-elf 6.1.0 target] (extracts to a directory called "cross", don't forget to install 'make' - I would recommend "apt-get install build-essential" to also add additional useful tools)
 
'''For Windows Subsytem for Linux host'''
* [https://drive.google.com/file/d/1zn37YmyVrtsPOfe88jZRZ_-_3_jzpXBP/view?usp=sharing i686-elf 13.1.0 target] ('''Important: extracts to a directory called "cross-tk"''')
 
'''For macOS host'''
 
x86_64-elf [https://formulae.brew.sh/formula/x86_64-elf-binutils binutils] and [https://formulae.brew.sh/formula/x86_64-elf-gcc gcc] (canonical target name x86_64-pc-elf) can be installed from [https://brew.sh homebrew]:
<pre>
$ brew install x86_64-elf-gcc
</pre>
i686-elf toolchain is also [https://formulae.brew.sh/formula/i686-elf-gcc available] in homebrew.
 
'''ARM prebuilt toolchains for multiple host platforms'''
 
ARM provides it's own prebuilt toolchain based upon GNU utilities for development targeting ARM systems.
 
* [https://developer.arm.com/open-source/gnu-toolchain/gnu-rm/downloads GNU ARM Embedded Toolchain]
'''For OSX host'''
 
'''Docker image'''
* [http://downloads.exquance.com/toolchain-x86_64-darwin.tar.bz2 i686-pc-elf 4.6.1 target with clang for x86_64 OSX host]
* [https://hub.docker.com/r/joshwyant/gcc-cross/ i686-elf 8.1.0 target]
* [https://docs.google.com/file/d/0BxDNp6DGU6SZcmlHVWpNblRnWWs/edit?usp=sharing x86_64-pc-elf Cross Compiler setup with GCC and Binutils for x86_64 OSX]
Retrieved from "https://osdev.wiki/wiki/GCC_Cross-Compiler"