linux-headers: Improve derivation, removing cross arg #28519
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Ericson2314
added
the
6.topic: cross-compilation
Ericson2314
added this to Needed by the big PR---nice to move pick off pieces of it and move here, rebasing the big PR on top
in Cross compilation
| @@ -12666,7 +12664,6 @@ with pkgs; | |||
| uclibc = callPackage ../os-specific/linux/uclibc { }; | |||
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| uclibcCross = lowPrio (callPackage ../os-specific/linux/uclibc { | |||
| inherit (buildPackages) linuxHeaders; | |||
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Now that its built in the same stage.
| in | ||
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| stdenv.mkDerivation { | ||
| stdenvNoCC.mkDerivation { |
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Um, why would this use stdenvNoCC given that the build needs to compile some stuff?
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Stdenv.cc is a build->host cc, but I need a build->build cc
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Such thing also belongs to the standard build environment even when cross compiling (e.g Buildroot and Yocto do). If nixpkgs doesn't anymore then that needs fixing instead.
| if stdenv.isArm then "arm" else | ||
| if stdenv.platform ? kernelArch then stdenv.platform.kernelArch else | ||
| abort "don't know what the kernel include directory is called for this platform"; | ||
| platform = hostPlatform.platform.kernelArch or ( |
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I think this fallback code (when kernelArch is not defined) should really go away.
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I tried not to change any interfaces. Mind doing this in a follow up commit?
Note that for native kernelArch isn't currently defined by default. There is hostPlatform.parsed.cpu.name however.
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kernelArch is always defined because the kernel derivation uses it unconditionally. And it must not be something else than kernelArch because the name we need to pass here is not something standard but an implementation detail of the Linux kernel.
- Perl is used at build time, so must be in `nativeBuildInputs`. It's not used at run time so it should not be in `buildInputs`, too. - Don't treat headers like a compiler---use the build and host platforms not host and target. Perhaps that would make sense if every library's headers could be a separate derivation, but since that is not feasible, best to keep the implementation and interface in the same stage. To do this, we used `stdenvNoCC` to get rid of the normal toolchain, and added a dependency for the toolchain targeting the build platform --- `buildPackages.stdenv.cc` --- thus everything is effectively slid a stage black.
Ericson2314
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With that note, I think I'll merge for the same reasons of unblocking everything else I want to do for 17.09.
@dezgeg We can move the kernelArch fallback code to https://github.com/NixOS/nixpkgs/blob/master/lib/systems/default.nix#L17 if you like.
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| buildInputs = [perl]; | ||
| # It may look odd that we use `stdenvNoCC`, and yet explicit depend on a cc. |
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@dezgeg Added this explanatory comment, as it does indeed look weird at first glance.
In NixOS#28519 / 791ce59 I made linux headers be intended to be used from the stage stage, as it would be if it were a library containing headers and code. I forgot to update glibc, however, so it was incorrectly using headers for the build platform, not host platform. This fixes that, basically reverting a small portion of changes I made a few months ago in 25edc47 and its parent. No native hashes are changed.
Motivation for this change
Perl is used at build time, so must be in
nativeBuildInputs. It's not used at run time so it should not be inbuildInputs, too.Don't treat headers like a compiler---use the build and host platforms not host and target. Perhaps that would make sense if every library's headers could be a separate derivation, but since that is not feasible, best to keep the implementation and interface in the same stage.
To do this, we used
stdenvNoCCto get rid of the normal toolchain, and added a dependency for the toolchain targeting the build platform ---buildPackages.stdenv.cc--- thus everything is effectively slid a stage black.Things done
(nix.useSandbox on NixOS,
or option
build-use-sandboxinnix.confon non-NixOS)
nix-shell -p nox --run "nox-review wip"./result/bin/)