On Wed, Feb 2, 2022 at 12:22 AM Nathan Chancellor nathan@kernel.org wrote:
-Wunaligned-access is a new warning in clang that is default enabled for arm and arm64 under certain circumstances within the clang frontend (see LLVM commit below). Under an ARCH=arm allmodconfig, there are 1284 total/70 unique instances of this warning (most of the instances are in header files), which is quite noisy.
To keep the build green through CONFIG_WERROR, only allow this warning with W=2, which seems appropriate according to its description: "warnings which occur quite often but may still be relevant".
This intentionally does not use the -Wno-... + -W... pattern that the rest of the Makefile does because this warning is not enabled for anything other than certain arm and arm64 configurations within clang so it should only be "not disabled", rather than explicitly enabled, so that other architectures are not disturbed by the warning.
Cc: stable@vger.kernel.org Link: https://github.com/llvm/llvm-project/commit/35737df4dcd28534bd3090157c224c19... Signed-off-by: Nathan Chancellor nathan@kernel.org
The warning seems important enough to be considered for W=1 on 32-bit arm, otherwise the chances of anyone actually fixing drivers for it is relatively slim. Can you point post the (sufficiently trimmed) output that you get with the warning enabled in an allmodconfig build?
I'm not sure why this is enabled by default for arm64, which does not have the problem with fixup handlers.
Arnd