error loading target specification: target-pointer-width: invalid type: string "64", expected u16 at line 8 column 32

[bvgcat]

I have not found a reference to my issue here or upstream, it should be a minor issue though.

tested:

• on surface-go
• master, both stable and longterm
• commit 321cb21, both stable and longterm

building '/nix/store/j4vf6pakyw88kjvlgmkjzq80ciipixkf-linux-6.15.9.drv'...
error: Cannot build '/nix/store/j4vf6pakyw88kjvlgmkjzq80ciipixkf-linux-6.15.9.drv'.
       Reason: builder failed with exit code 2.
       Output paths:
         /nix/store/89m8bf1r49vg9ccgzj013gzxhdb373il-linux-6.15.9
         /nix/store/glna2nri4ilbf5wwggrfdv9jx6545nmz-linux-6.15.9-dev
         /nix/store/hwr2wqlankwfml9hi631nnykd8nd1kyh-linux-6.15.9-modules
       Last 25 log lines:
       >   AR      /build/linux-6.15.9/build/tools/bpf/resolve_btfids/libsubcmd/libsubcmd.a
       >   INSTALL /build/linux-6.15.9/build/tools/bpf/resolve_btfids/libsubcmd//include/subcmd/exec-cmd.h
       >   INSTALL /build/linux-6.15.9/build/tools/bpf/resolve_btfids/libsubcmd//include/subcmd/help.h
       >   INSTALL /build/linux-6.15.9/build/tools/bpf/resolve_btfids/libsubcmd//include/subcmd/pager.h
       >   INSTALL /build/linux-6.15.9/build/tools/bpf/resolve_btfids/libsubcmd//include/subcmd/parse-options.h
       >   INSTALL /build/linux-6.15.9/build/tools/bpf/resolve_btfids/libsubcmd//include/subcmd/run-command.h
       >   INSTALL libsubcmd_headers
       >   HOSTCC  /build/linux-6.15.9/build/tools/bpf/resolve_btfids/main.o
       >   HOSTCC  /build/linux-6.15.9/build/tools/bpf/resolve_btfids/rbtree.o
       >   HOSTCC  /build/linux-6.15.9/build/tools/bpf/resolve_btfids/zalloc.o
       >   HOSTCC  /build/linux-6.15.9/build/tools/bpf/resolve_btfids/string.o
       >   HOSTCC  /build/linux-6.15.9/build/tools/bpf/resolve_btfids/ctype.o
       >   HOSTCC  /build/linux-6.15.9/build/tools/bpf/resolve_btfids/str_error_r.o
       >   HOSTLD  /build/linux-6.15.9/build/tools/bpf/resolve_btfids/resolve_btfids-in.o
       >   LINK     resolve_btfids
       >   RUSTC L rust/core.o
       > error: error loading target specification: target-pointer-width: invalid type: string "64", expected u16 at line 8 column 32
       >   |
       >   = help: run `rustc --print target-list` for a list of built-in targets
       >
       > make[3]: *** [../rust/Makefile:494: rust/core.o] Error 1
       > make[2]: *** [/build/linux-6.15.9/Makefile:1280: prepare] Error 2
       > make[1]: *** [/build/linux-6.15.9/Makefile:248: __sub-make] Error 2
       > make[1]: Leaving directory '/build/linux-6.15.9/build'
       > make: *** [Makefile:248: __sub-make] Error 2
       For full logs, run:
         nix log /nix/store/j4vf6pakyw88kjvlgmkjzq80ciipixkf-linux-6.15.9.drv
error: Cannot build '/nix/store/j4vf6pakyw88kjvlgmkjzq80ciipixkf-linux-6.15.9.drv'.
       Reason: builder failed with exit code 2.
       Output paths:
         /nix/store/89m8bf1r49vg9ccgzj013gzxhdb373il-linux-6.15.9
         /nix/store/glna2nri4ilbf5wwggrfdv9jx6545nmz-linux-6.15.9-dev
         /nix/store/hwr2wqlankwfml9hi631nnykd8nd1kyh-linux-6.15.9-modules
       Last 25 log lines:
       >   AR      /build/linux-6.15.9/build/tools/bpf/resolve_btfids/libsubcmd/libsubcmd.a
       >   INSTALL /build/linux-6.15.9/build/tools/bpf/resolve_btfids/libsubcmd//include/subcmd/exec-cmd.h
       >   INSTALL /build/linux-6.15.9/build/tools/bpf/resolve_btfids/libsubcmd//include/subcmd/help.h
       >   INSTALL /build/linux-6.15.9/build/tools/bpf/resolve_btfids/libsubcmd//include/subcmd/pager.h
       >   INSTALL /build/linux-6.15.9/build/tools/bpf/resolve_btfids/libsubcmd//include/subcmd/parse-options.h
       >   INSTALL /build/linux-6.15.9/build/tools/bpf/resolve_btfids/libsubcmd//include/subcmd/run-command.h
       >   INSTALL libsubcmd_headers
       >   HOSTCC  /build/linux-6.15.9/build/tools/bpf/resolve_btfids/main.o
       >   HOSTCC  /build/linux-6.15.9/build/tools/bpf/resolve_btfids/rbtree.o
       >   HOSTCC  /build/linux-6.15.9/build/tools/bpf/resolve_btfids/zalloc.o
       >   HOSTCC  /build/linux-6.15.9/build/tools/bpf/resolve_btfids/string.o
       >   HOSTCC  /build/linux-6.15.9/build/tools/bpf/resolve_btfids/ctype.o
       >   HOSTCC  /build/linux-6.15.9/build/tools/bpf/resolve_btfids/str_error_r.o
       >   HOSTLD  /build/linux-6.15.9/build/tools/bpf/resolve_btfids/resolve_btfids-in.o
       >   LINK     resolve_btfids
       >   RUSTC L rust/core.o
       > error: error loading target specification: target-pointer-width: invalid type: string "64", expected u16 at line 8 column 32
       >   |
       >   = help: run `rustc --print target-list` for a list of built-in targets
       >
       > make[3]: *** [../rust/Makefile:494: rust/core.o] Error 1
       > make[2]: *** [/build/linux-6.15.9/Makefile:1280: prepare] Error 2
       > make[1]: *** [/build/linux-6.15.9/Makefile:248: __sub-make] Error 2
       > make[1]: Leaving directory '/build/linux-6.15.9/build'
       > make: *** [Makefile:248: __sub-make] Error 2
       For full logs, run:
         nix log /nix/store/j4vf6pakyw88kjvlgmkjzq80ciipixkf-linux-6.15.9.drv
error: Cannot build '/nix/store/1i1ifra5yv9hi0lr1jq30jspy293j4cq-nixos-system-surface-go-25.11.20251124.0fde19f.drv'.
       Reason: 1 dependency failed.
       Output paths:
         /nix/store/jnikbn65inr725bmclb600c205b687r7-nixos-system-surface-go-25.11.20251124.0fde19f
Command 'ssh -o ControlMaster=auto -o ControlPath=/tmp/nixos-rebuild.w0quhxqt/ssh-%n -o ControlPersist=60 root@homeserver -- nix --extra-experimental-features ''"'"'nix-command flakes'"'"'' build ''"'"'/nix/store/1i1ifra5yv9hi0lr1jq30jspy293j4cq-nixos-system-surface-go-25.11.20251124.0fde19f.drv^*'"'"'' --print-out-paths --no-link' returned non-zero exit status 1.

[xieve]

This is appearing for me after I selectively only updated nixpkgs (and not nixos-hardware) on my system, which seems extremely strange to me, as I am not overriding nixos-hardware's inputs either. I switched to stable from lts because of #1600. Thus, this is completely blocking updates for me right now, while I have an ongoing systemd issue that is fixed upstream :(

Edit:

• To clarify, I'm currently running 6.15.9, yet the rebuild is failing.
• I'm using a Surface Pro 9
• I just tested this and I'm getting the same error on ea1e368 (6.15.6)

[Majiir]

This is appearing for me after I selectively only updated nixpkgs (and not nixos-hardware) on my system

This was a great hint! I bisected it to NixOS/nixpkgs#457185. (The error happens in configureStage, so it's easy to tell whether a version is good or bad without compiling the whole kernel.)

That PR changes something about the target specifications. @lblasc Do you know what we can do about error loading target specification above?

[8bitbuddhist]

Same here, anytime I try building either surface kernel, the build fails.

[binarin]

The simple patch below is enough, add it to configuration like so:

        boot.kernelPatches = [{
            name = "rust-1.91-fix";
            patch = ../hacks/rust-fix.patch;
        }];

diff --recursive -u linux-6.15.9.orig/scripts/generate_rust_target.rs linux-6.15.9/scripts/generate_rust_target.rs
--- linux-6.15.9.orig/scripts/generate_rust_target.rs	2025-08-01 10:51:29.000000000 +0200
+++ linux-6.15.9/scripts/generate_rust_target.rs	2025-11-29 12:30:54.792372738 +0100
@@ -225,7 +225,7 @@
         ts.push("features", features);
         ts.push("llvm-target", "x86_64-linux-gnu");
         ts.push("supported-sanitizers", ["kcfi", "kernel-address"]);
-        ts.push("target-pointer-width", "64");
+        ts.push("target-pointer-width", 64);
     } else if cfg.has("X86_32") {
         // This only works on UML, as i386 otherwise needs regparm support in rustc
         if !cfg.has("UML") {

[Majiir]

Thanks! It looks like this is the upstream kernel commit we need.