On Mon, Jan 23, 2023 at 09:07:16AM -0600, Segher Boessenkool wrote: > Hi! > > On Wed, Jan 11, 2023 at 08:05:04PM -0700, Nathan Chancellor wrote: > > When clang's -Qunused-arguments is dropped from KBUILD_CPPFLAGS, there > > are several warnings in the PowerPC vDSO: > > > > clang-16: error: -Wl,-soname=linux-vdso32.so.1: 'linker' input unused > > [-Werror,-Wunused-command-line-argument] > > clang-16: error: -Wl,--hash-style=both: 'linker' input unused > > [-Werror,-Wunused-command-line-argument] > > clang-16: error: argument unused during compilation: '-shared' > > [-Werror,-Wunused-command-line-argument] > > > > clang-16: error: argument unused during compilation: '-nostdinc' > > [-Werror,-Wunused-command-line-argument] > > clang-16: error: argument unused during compilation: '-Wa,-maltivec' > > [-Werror,-Wunused-command-line-argument] > > There is nothing wrong with the warnings, but as usual, -Werror is very > counterproductive. > > > The first group of warnings point out that linker flags were being added > > to all invocations of $(CC), even though they will only be used during > > the final vDSO link. Move those flags to ldflags-y. > > Which is explicitly allowed, and won't do anything, so nothing harmful > either. It is not a bad idea to avoid this if that is trivial to do, > of course.
I think this patch shows that it is trivial to do this, the primary core of the diff is only a few lines. > > The second group of warnings are compiler or assembler flags that will > > be unused during linking. Filter them out from KBUILD_CFLAGS so that > > they are not used during linking. > > And here it is even more obviously fine. If you need obfuscation like > in your patch, it is better not to do this imo. I do not think this patch really obfuscates anything? The filtering is pretty clear to me. If this is a real objection to the patch, I suppose we could just localize '-Qunused-arguments' to this Makefile and be done with it but I do not think this change is a bad solution to the problem either. Cheers, Nathan
