On Tue, Jul 21, 2020 at 12:40 PM Greg KH gregkh@linuxfoundation.org wrote:
On Mon, Jul 20, 2020 at 09:19:38PM -0700, Fangrui Song wrote:
When CROSS_COMPILE is set (e.g. aarch64-linux-gnu-), if $(CROSS_COMPILE)elfedit is found at /usr/bin/aarch64-linux-gnu-elfedit, GCC_TOOLCHAIN_DIR will be set to /usr/bin/. --prefix= will be set to /usr/bin/ and Clang as of 11 will search for both $(prefix)aarch64-linux-gnu-$needle and $(prefix)$needle.
GCC searchs for $(prefix)aarch64-linux-gnu/$version/$needle, $(prefix)aarch64-linux-gnu/$needle and $(prefix)$needle. In practice, $(prefix)aarch64-linux-gnu/$needle rarely contains executables.
To better model how GCC's -B/--prefix takes in effect in practice, newer Clang (since https://github.com/llvm/llvm-project/commit/3452a0d8c17f7166f479706b293caf6a...) only searches for $(prefix)$needle. Currently it will find /usr/bin/as instead of /usr/bin/aarch64-linux-gnu-as.
Set --prefix= to $(GCC_TOOLCHAIN_DIR)$(CROSS_COMPILE) (/usr/bin/aarch64-linux-gnu-) so that newer Clang can find the appropriate cross compiling GNU as (when -no-integrated-as is in effect).
Reported-by: Nathan Chancellor natechancellor@gmail.com Signed-off-by: Fangrui Song maskray@google.com Reviewed-by: Nathan Chancellor natechancellor@gmail.com Tested-by: Nathan Chancellor natechancellor@gmail.com Tested-by: Nick Desaulniers ndesaulniers@google.com Link: https://github.com/ClangBuiltLinux/linux/issues/1099
Changes in v2:
- Updated description to add tags and the llvm-project commit link.
- Fixed a typo.
<formletter>
This is not the correct way to submit patches for inclusion in the stable kernel tree. Please read: https://www.kernel.org/doc/html/latest/process/stable-kernel-rules.html for how to do this properly.
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Hi Fangrui,
your patch needs to be accepted first in Linus tree - among other things to have a unique commit-id for inclusion into any affected Linux-stable trees.
Regards, - Sedat -