l...@gnu.org (Ludovic Courtès) skribis:
> Mark H Weaver <m...@netris.org> skribis:
>
>> It would be great if we had a build hook to enable guix-daemon to
>> natively build packages for any system supported by qemu, by running the
>> build processes within qemu.
>
> QEMU has a ‘qemu-binfmt-conf.sh’ script that installs binfmt_misc
> handlers for all the architecture-specific ELF variants. Once you’ve
> run this script, you can transparently run, say, ARM executables (the
> kernel takes care of invoking ‘qemu-arm’ for you).
[...]
> Then we just need to tell the daemon to not complain (“but I’m an
> 'x86_64-linux'”).
The attached patch does that.
However, there’s an added complication: the file name of the qemu-*
executables registered in binfmt_misc are apparently resolved relative
to the root directory of the process that does ‘execve’.
So we would need to add a guix-daemon --chroot-directory=DIR argument
for each element in the closure of QEMU. Not great.
Thoughts?
Ludo’.
diff --git a/nix/libstore/build.cc b/nix/libstore/build.cc
index 9b7bb5391..bca75a4f9 100644
--- a/nix/libstore/build.cc
+++ b/nix/libstore/build.cc
@@ -1672,15 +1672,6 @@ void DerivationGoal::startBuilder()
f.exceptions(boost::io::all_error_bits ^ boost::io::too_many_args_bit);
startNest(nest, lvlInfo, f % showPaths(missingPaths) % curRound % nrRounds);
- /* Right platform? */
- if (!canBuildLocally(drv.platform)) {
- if (settings.printBuildTrace)
- printMsg(lvlError, format("@ unsupported-platform %1% %2%") % drvPath % drv.platform);
- throw Error(
- format("a `%1%' is required to build `%3%', but I am a `%2%'")
- % drv.platform % settings.thisSystem % drvPath);
- }
-
/* Note: built-in builders are *not* running in a chroot environment so
that we can easily implement them in Guile without having it as a
derivation input (they are running under a separate build user,
@@ -2305,6 +2296,18 @@ void DerivationGoal::runChild()
execve(drv.builder.c_str(), stringsToCharPtrs(args).data(), stringsToCharPtrs(envStrs).data());
+ int error = errno;
+
+ /* Right platform? */
+ if (error == ENOEXEC && !canBuildLocally(drv.platform)) {
+ if (settings.printBuildTrace)
+ printMsg(lvlError, format("@ unsupported-platform %1% %2%") % drvPath % drv.platform);
+ throw Error(
+ format("a `%1%' is required to build `%3%', but I am a `%2%'")
+ % drv.platform % settings.thisSystem % drvPath);
+ }
+
+ errno = error;
throw SysError(format("executing `%1%'") % drv.builder);
} catch (std::exception & e) {
