Compilation error: can't find crate for `std`; the `x86_64-linux-kernel` target may not be installed

[wecing]

Compiling the current head of the rust branch failed for me. Here is my setup:

> rustup toolchain install nightly-2020-08-27
> rustup default nightly-2020-08-27
> rustup component add rust-src
> cat .config | grep -E '(RUST|CARGO)'
CONFIG_HAS_RUST=y
CONFIG_RUSTC_VERSION=14700
CONFIG_CARGO_VERSION=14700
CONFIG_RUST_EXAMPLE=y
CONFIG_RANDOM_TRUST_CPU=y
# CONFIG_RANDOM_TRUST_BOOTLOADER is not set
# CONFIG_IMA_SECURE_AND_OR_TRUSTED_BOOT is not set
CONFIG_SYSTEM_TRUSTED_KEYRING=y
CONFIG_SYSTEM_TRUSTED_KEYS=""
# CONFIG_SECONDARY_TRUSTED_KEYRING is not set
> make LLVM=1
  ...
  CARGO     arch/x86/entry/vdso/out/libvdso-image.a
   Compiling core v0.0.0 (/home/$USER/.rustup/toolchains/nightly-2020-08-27-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/core)
   Compiling kernel v0.1.0 (/home/$USER/Code/rust-for-linux/rust/kernel)
   Compiling rustc-std-workspace-core v1.99.0 (/home/$USER/.rustup/toolchains/nightly-2020-08-27-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/rustc-std-workspace-core)
   Compiling compiler_builtins v0.1.32
   Compiling alloc v0.0.0 (/home/$USER/.rustup/toolchains/nightly-2020-08-27-x86_64-unknown-linux-gnu/lib/rustlib/src/rust/library/alloc)
   Compiling bitflags v1.2.1
   Compiling shlex v0.1.1 (/home/$USER/Code/rust-for-linux/rust/shlex)
error[E0463]: can't find crate for `std`
  |
  = note: the `x86_64-linux-kernel` target may not be installed

error: aborting due to previous error

For more information about this error, try `rustc --explain E0463`.
error: could not compile `shlex`.

To learn more, run the command again with --verbose.
warning: build failed, waiting for other jobs to finish...
error: build failed
make[3]: *** [scripts/Makefile.build:318: arch/x86/entry/vdso/out/libvdso-image.a] Error 101
make[2]: *** [scripts/Makefile.build:518: arch/x86/entry/vdso] Error 2
make[1]: *** [scripts/Makefile.build:518: arch/x86/entry] Error 2
make: *** [Makefile:1838: arch/x86] Error 2

Is there something missing in Documentation/rust/quick-start.rst?

[kloenk]

This should resolve itself, when #25 gets resolved.

[wecing]

@kloenk Is it possible to workaround this issue before #25 lands?

[ojeda]

@wecing It may work now since we don't depend on shlex anymore and we use our own target. I also rewrote the quick start guide a bit, in case you want to take a look.

[wecing]

@ojeda Thank you! Unfortunately it still doesn't work for me:

> git log -1
commit 514443c678e50021917dfe5b9e4a427559e9ec82 (HEAD -> rust, origin/rust, origin/HEAD)
Merge: 2874653450f 5c3df5ae897
Author: Miguel Ojeda
Date:   Sun Nov 29 00:03:27 2020 +0100

    Merge pull request #37 from Rust-for-Linux/rust-ci-builddir

    CI: test O= builds too
> make menuconfig
> make clean
> make LLVM=1
  ...
  CALL    scripts/checksyscalls.sh
  CALL    scripts/atomic/check-atomics.sh
  DESCEND  objtool
  CHK     include/generated/compile.h
  CARGO     arch/x86/entry/vdso/libvdso-image.a
error: manifest path `./arch/x86/entry/vdso/Cargo.toml` does not exist
make[3]: *** [scripts/Makefile.build:329: arch/x86/entry/vdso/libvdso-image.a] Error 101
make[2]: *** [scripts/Makefile.build:529: arch/x86/entry/vdso] Error 2
make[1]: *** [scripts/Makefile.build:529: arch/x86/entry] Error 2
make: *** [Makefile:1833: arch/x86] Error 2

Since the previous error message I saw was about rust std, I actually did try to compile that from latest rust source code:

> ./x.py build --stage 1 --host x86_64-unknown-linux-gnu --target x86_64-linux-kernel library/std
Assembling stage1 compiler (x86_64-unknown-linux-gnu)
Building stage1 std artifacts (x86_64-unknown-linux-gnu -> x86_64-linux-kernel)
   Compiling libc v0.2.79
   ...
   Compiling object v0.22.0
   Compiling addr2line v0.14.0
   Compiling std v0.0.0 (/home/$USER/Code/sources/rust/library/std)
warning: dropping unsupported crate type `dylib` for target `x86_64-linux-kernel`

error[E0432]: unresolved imports `libc::c_int`, `libc::c_void`
  --> library/std/src/sys_common/net.rs:17:12
   |
17 | use libc::{c_int, c_void};
   |            ^^^^^  ^^^^^^ no `c_void` in the root
   |            |
   |            no `c_int` in the root

Not sure what was causing that failure, but it probably doesn't matter anymore.

[ojeda]

@wecing Thanks for trying again!

CARGO arch/x86/entry/vdso/libvdso-image.a

@kloenk This is triggered by the $(obj)/lib%.a change, now it matches things we don't want.

[kloenk]

@kloenk This is triggered by the $(obj)/lib%.a change, now it matches things we don't want.

Oh, not good. But without that change it also does not work. So no idea on how to fix it from my side at this time.

I changed it so, it detects if it's a module or a builtin.