Porting GCC to your OS: Difference between revisions

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(A short description of what GCC needs from the standard library)
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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 configure options <tt>--with-build-sysroot=/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:Porting]]
[[Category:Compilers]]
[[Category:Compilers]]

Latest revision as of 20:22, 10 July 2023

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 configure options --with-build-sysroot=/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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