Hi Christoph, El Tue, May 23, 2017 at 12:36:01AM -0700 Christoph Hellwig ha dit:
> On Mon, May 22, 2017 at 02:13:26PM -0700, Matthias Kaehlcke wrote: > > The function is not used when CONFIG_HAVE_EFFICIENT_UNALIGNED_ACCESS=y. > > Adding the #ifdef fixes the following warning when building with clang: > > > > lib/zlib_inflate/inffast.c:31:1: error: unused function 'get_unaligned16' > > [-Werror,-Wunused-function] > > > > Signed-off-by: Matthias Kaehlcke <m...@chromium.org> > > --- > > Note: Usually we would use the __maybe_unused attribute to silence the > > warning. Since this code is used in the kernel decompression stub rather > > than in the kernel itself we can't include <linux/compiler.h> with the > > definition of __maybe_unused (it would be possible for some platforms, > > however for powerpc the build fails with a compiler error). We could > > redefine __maybe_unused or use the raw __attribute__((unused)), but > > using the #ifdef is a simpler solution. > > Usually one would take a look at the root cause. And then remove > get_unaligned16 entirely and replace it with the get_unaligned > helper provided by the kernel. Thanks for the suggestion to use get_unaligned(). Unfortunately that doesn't work without hackery, at least for powerpc. We can add arch/powerpc/include to the include paths of the decompression stub to be able to include <asm/unaligned.h>, however the build then fails with "undefined reference to `get_unaligned'", because on powerpc get/put_unaligned are defined inside an #ifdef __KERNEL__ block. We probably don't want to define __KERNEL__ for the decompression stub just to avoid an #ifndef in the zlib code.
