(staging) systemd fails to cross compile to arm

[sorki]

Describe the bug

Building systemd-boot with EFI support uses host cc and ld correctly but with target arch set to arm resulting in

/nix/store/k930l9lckxjf4zmafv4aapvdbd2sibmj-gcc-wrapper-9.3.0/bin/ld -o src/boot/efi/systemd_boot.so -T /nix/store/zkghrargax07rq16d6wa4r68wa1d7p30-gnu-efi-3.0.11-armv7l-unknown-linux-gnueabihf/lib/elf_arm_efi.lds -shared -Bsymbolic -nostdlib -znocombreloc -L /nix/store/zkghrargax07rq16d6wa4r68wa1d7p30-gnu-efi-3.0.11-armv7l-unknown-linux-gnueabihf/lib /nix/store/zkghrargax07rq16d6wa4r68wa1d7p30-gnu-efi-3.0.11-armv7l-unknown-linux-gnueabihf/lib/crt0-efi-arm.o --defsym=EFI_SUBSYSTEM=0xa src/boot/efi/disk.c.o src/boot/efi/graphics.c.o src/boot/efi/measure.c.o src/boot/efi/pe.c.o src/boot/efi/util.c.o src/boot/efi/boot.c.o src/boot/efi/console.c.o src/boot/efi/crc32.c.o src/boot/efi/random-seed.c.o src/boot/efi/sha256.c.o src/boot/efi/shim.c.o -lefi -lgnuefi /nix/store/ppbczakh03k4ag97v966bh5aw6ps7dqr-armv7l-unknown-linux-gnueabihf-stage-final-gcc-debug-9.3.0/lib/gcc/armv7l-unknown-linux-gnueabihf/9.3.0/libgcc.a
/nix/store/3b3ighb83nhifa1v4n7855hlbdl1mhf9-binutils-2.31.1/bin/ld: cannot represent machine `arm'

Workaround is to disable EFI completely by adding the following to mesonFlags

(if stdenv.hostPlatform != stdenv.targetPlatform then "-Defi=false" else "")

but I would like to fix this correctly.

There's also -Defi-ld flag which can be used to pass another ld but I'm not sure if using target's ld is the right approach here.

To Reproduce

Cross-build to armv7l with current staging.

nixpkgs.crossSystem.system = "armv7l-linux";

Notify maintainers

Ping cross gurus @Mic92 @Ericson2314 @matthewbauer

[sorki]

Hm, the workaround doesn't seem to be enough and I've switched it to

    #(if !stdenv.hostPlatform.isEfi then "-Dgnu-efi=false" else "-Dgnu-efi=true")
    "-Defi=false"

[sorki]

Looks like #72802 adds support for withEfi flag.

[russetrob]

Firstly, I assume you did check the resulting package runs on arm? I'd be suspicious it's not cross-compiling at all!
You could approach the problem the other way, and get efi linked into the arm build.
For this you'd need to find out why your linker can't understand "arm" as machine name. For instance on a mingw build of ld to cross compile to arm, ld accepts machine of "arm".
You might need to hack the linker command to take option "-marmelf".
It might help take the linker and run "/nix/store/k930l9lckxjf4zmafv4aapvdbd2sibmj-gcc-wrapper-9.3.0/bin/ld --help" the output should specify emulations and output formats supported (Probably a good idea to paste it here, for cross-compile experts to mull over).

[sorki]

Thanks, the only problem is the EFI (systemd-boot) part, it does cross-compile and works correctly it without it.

Trouble (for me :)) is expressing your suggestion using pkgs.buildPackages or similar. Will take a look at hacking the linker option but my suspicion is that it's not using the correct linker. 🐱 is interefering with my github buttons.

[sorki]

Fixed by a239864