On Thu, Jul 27, 2023, at 23:36, Nathan Chancellor wrote: > Hi Tiezhu and Arnd, > > On Thu, Jun 22, 2023 at 10:13:38PM +0800, Tiezhu Yang wrote: >> Now we specify the minimal version of GCC as 5.1 and Clang/LLVM as 11.0.0 >> in Documentation/process/changes.rst, __CHAR_BIT__ and __SIZEOF_LONG__ are >> usable, it is probably fine to unify the definition of __BITS_PER_LONG as >> (__CHAR_BIT__ * __SIZEOF_LONG__) in asm-generic uapi bitsperlong.h. >> >> In order to keep safe and avoid regression, only unify uapi bitsperlong.h >> for some archs such as arm64, riscv and loongarch which are using newer >> toolchains that have the definitions of __CHAR_BIT__ and __SIZEOF_LONG__. >> >> Suggested-by: Xi Ruoyao <xry111@xxxxxxxxxxx> >> Link: https://lore.kernel.org/all/d3e255e4746de44c9903c4433616d44ffcf18d1b.camel@xxxxxxxxxxx/ >> Suggested-by: Arnd Bergmann <arnd@xxxxxxxx> >> Link: https://lore.kernel.org/linux-arch/a3a4f48a-07d4-4ed9-bc53-5d383428bdd2@xxxxxxxxxxxxxxxx/ >> Signed-off-by: Tiezhu Yang <yangtiezhu@xxxxxxxxxxx> >> --- > > I think this change has backwards compatibility concerns, as it breaks > building certain host tools on the stable releases (at least 6.4 and > 6.1, as that is where I noticed this). I see the following error on my > aarch64 system: > > $ make -skj"$(nproc)" ARCH=x86_64 CROSS_COMPILE=x86_64-linux- > mrproper defconfig prepare > In file included from /usr/include/asm/bitsperlong.h:1, > from /usr/include/asm-generic/int-ll64.h:12, > from /usr/include/asm-generic/types.h:7, > from /usr/include/asm/types.h:1, > from tools/include/linux/types.h:13, > from tools/arch/x86/include/asm/orc_types.h:9, > from scripts/sorttable.h:96, > from scripts/sorttable.c:201: > tools/include/asm-generic/bitsperlong.h:14:2: error: #error > Inconsistent word size. Check asm/bitsperlong.h > 14 | #error Inconsistent word size. Check asm/bitsperlong.h > | ^~~~~ Thanks for the report. I'm still struggling to figure out what exactly is going wrong here, and if this is a bug in the patch I merged, or an existing bug that now causes a build failure instead of some other problem. > A reverse bisect of 6.4 to 6.5-rc1 points to this patch. This Fedora > rawhide container has kernel-headers 6.5.0-0.rc2.git0.1.fc39 and the > error disappears when I downgrade to 6.4.0-0.rc7.git0.1.fc39. I have not > done a ton of triage/debugging so far, as I am currently hunting down > other regressions, but I figured I would get an initial report out, > since I noticed it when validating LLVM from the new release/17.x > branch. If there is any additional information I can provide or patches > I can test, I am more than happy to do so. One thing I think is going wrong here is that scripts/sorttable.c is meant to run on the host (arm64) but includes the target (x86) orc_Types.h header and the kernel-internal asm/bitsperlong.h instead of the uapi version. The sanity check in the kernel-side header is intended to cross-check the CONFIG_64BIT value against the __BITS_PER_LONG constant from the header. My first guess would be that this only worked by accident if the headers defaulted to "#define __BITS_PER_LONG 32" in and #undef CONFIG_64BIT" when include/generated/autoconf.h, but now the __BITS_PER_LONG value is actually correct. Arnd
