Porting GCC to your OS: Difference between revisions

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(A short description of what GCC needs from the standard library)
(Rewrite page with some basic pointers instead of the useless stuff that was already there, the sysroot stuff is pretty important here, other articles covers the rest)
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* Read [[GCC Cross-Compiler]].
:''Note that the [[GCC Cross-Compiler]] page is intended to include the information below (as well as filling in the To-Dos) once it is finished. Unless someone else does it first, I'll do so once my PDCLib is finished.'' - [[User:Solar|MartinBaute]]
* Make a [[OS Specific Toolchain]].
* Read [[Hosted GCC Cross-Compiler]].
⚫
* Have a sufficient [[C Library]]. GCC is fairly portable and needs the C standard library, and some extensions from POSIX. It needs fork and exec, for instance, to run the assembler and linker. You will need a C++ standard library (such as libstdc++) as GCC is now written in [[C++]].
* Cross-compile libgmp, libmpc, libmpfr and other dependencies with instructions in [[Cross-Porting Software]].
* Likewise cross-compile [[Binutils]] and [[GCC]], but pass the special confifigure options <tt>--with-sysroot-build=/your/sysroot</tt> and <tt>--with-sysroot=/</tt>. The option <tt>--with-build-sysroot</tt> option uses that [[sysroot]] for the duration of the build, but the final program does not remember it. <tt>--with-sysroot=/</tt> should not be needed or should be set to the empty string, but some binutils/gcc versions are buggy and require it, which has the disadvantage the final toolchain might use <tt>//foo</tt> instead of <tt>/foo</tt>. You should ''only'' pass these options to the Binutils and GCC builds, some other packages also have a <tt>--with-sysroot</tt> option, but it instead means a libtool feature you should ''not'' use.
* Become self-hosting and complete [[Bare_Bones#Bare_Bones_II|Bare Bones II]]. Congratulations.


⚫
== See Also ==
First, you should understand [[How kernel, compiler, and C library work together]]. If any of the next steps give you trouble, the information given in that document should give you an idea of what is missing.
* [[Binutils]]

* [[Cross-Porting Software]]
Next, you should build a [[GCC Cross-Compiler]] for your platform.
* [[GCC]]

* [[GCC Cross-Compiler]]
:''ToDo: elaborate on [[GCC]]'s platform description, and how to set up your own if you don't want to use an existing one.''
* [[Hosted GCC Cross-Compiler]]

* [[OS Specific Toolchain]]
Then, you need a C standard library for your platform - at least those parts required by GCC.
* [[Sysroot]]

⚫
To do this you need a [[C Library]] for your OS. GCC is fairly portable and needs the C standard library, and some extensions from POSIX. It needs fork and exec, for instance, to run the assembler and linker. You will need a C++ standard library (such as libstdc++) as GCC is now written in [[C++]].

Finally, you would use the cross-compiler to compile [[GCC]] ''to run on your platform''.

Just to be sure, you would use that "native" [[GCC]] to compile itself (to be sure it could, and for weeding out any issues that might arise from cross-compilation). Congratulations, you are now what people call "self-hosted", i.e. you no longer need some other OS to do development work. (Provided you have a working editor for your platform.)

⚫
==See Also==
===External Links===
*[http://www.scratchbox.org Scratch Box]
*[http://libosdk.berlios.de/wiki/index.php/Binutils LibOSDK Wiki]


[[Category:Compilers]]
[[Category:Compilers]]

Revision as of 16:32, 14 October 2017

Difficulty level

Master
This page is a work in progress.
This page may thus be incomplete. Its content may be changed in the near future.
  • Read GCC Cross-Compiler.
  • Make a OS Specific Toolchain.
  • Read Hosted GCC Cross-Compiler.
  • Have a sufficient C Library. GCC is fairly portable and needs the C standard library, and some extensions from POSIX. It needs fork and exec, for instance, to run the assembler and linker. You will need a C++ standard library (such as libstdc++) as GCC is now written in C++.
  • Cross-compile libgmp, libmpc, libmpfr and other dependencies with instructions in Cross-Porting Software.
  • Likewise cross-compile Binutils and GCC, but pass the special confifigure options --with-sysroot-build=/your/sysroot and --with-sysroot=/. The option --with-build-sysroot option uses that sysroot for the duration of the build, but the final program does not remember it. --with-sysroot=/ should not be needed or should be set to the empty string, but some binutils/gcc versions are buggy and require it, which has the disadvantage the final toolchain might use //foo instead of /foo. You should only pass these options to the Binutils and GCC builds, some other packages also have a --with-sysroot option, but it instead means a libtool feature you should not use.
  • Become self-hosting and complete Bare Bones II. Congratulations.

See Also

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