From 2affd455a40a28825f356307ce5bd8fa2f202217 Mon Sep 17 00:00:00 2001 From: Adam Joseph Date: Fri, 16 Jun 2023 14:15:36 -0700 Subject: gccCrossStageStatic: enable dynamic libraries, rename to gccWithoutTargetLibc This commit allows `gccCrossStageStatic` to build dynamically-linked libraries. Since is no longer restricted to building static libraries its name is no longer appropriate, and this commit also renames it to the more-accurate `gccWithoutTargetLibc`. By default, you can't build a gcc that knows how to create dynamic libraries unless you have already built the targetPlatform libc. Because of this, our gcc cross-compiler is built in two stages: 1. Build a cross-compiler (gccCrossStageStatic) that can build only static libraries. 2. Use gccCrossStageStatic to compile the targetPlatform libc. 3. Use the targetPlatform libc to build a fully-capable cross compiler. You might notice that this pattern looks very similar to what we do with `xgcc` in the stdenv bootstrap. Indeed it is! I would like to work towards getting the existing stdenv bootstrap to handle cross compilers as well. However we don't want to cripple `stdenv.xgcc` by taking away its ability to build dynamic libraries. It turns out that the only thing gcc needs the targetPlatform libc for is to emit a DT_NEEDED for `-lc` into `libgcc.so`. That's it! And since we don't use `gccCrossStageStatic` to build anything other than libc, it's safe to omit the `DT_NEEDED` because that `libgcc` will never be loaded by anything other than `libc`. So `libc` will already be in the process's address space. Other people have noticed this; crosstool-ng has been using this approach for a very long time: https://github.com/crosstool-ng/crosstool-ng/blob/36ad0b17a732aaffe4701d5d8d410d6e3e3abba9/scripts/build/cc/gcc.sh#L638-L640 --- pkgs/os-specific/windows/default.nix | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) (limited to 'pkgs/os-specific/windows/default.nix') diff --git a/pkgs/os-specific/windows/default.nix b/pkgs/os-specific/windows/default.nix index 8d6dd50548e..12859de8a20 100644 --- a/pkgs/os-specific/windows/default.nix +++ b/pkgs/os-specific/windows/default.nix @@ -20,7 +20,7 @@ lib.makeScope newScope (self: with self; { crossThreadsStdenv = overrideCC crossLibcStdenv (if stdenv.hostPlatform.useLLVM or false then buildPackages.llvmPackages_8.clangNoLibcxx - else buildPackages.gccCrossStageStatic.override (old: { + else buildPackages.gccWithoutTargetLibc.override (old: { bintools = old.bintools.override { libc = libcCross; }; -- cgit 1.4.1