On Fri, Jul 28, 2023 at 01:00:30PM +0200, Arnd Bergmann wrote: > 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. Totally understandable, I was really confused at first too. > > 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 Right. I will note sorttable is not the only utility that has this issue, I see the same problem coming from several files in tools/lib/subcmd when building several different architectures and arch/x86/entry/vdso/vdso2c.c at the very least. > 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. That seems like a reasonable theory. I am still busy looking into other things today but I can try to double back to this on Monday if you don't make any progress. Cheers, Nathan
