On Wed, May 27, 2020 at 3:53 PM Arnd Bergmann <a...@arndb.de> wrote: > > When using the clang integrated assembler, we get a reference > to __force_order that should normally get ignored in a few > rare cases: > > ERROR: modpost: "__force_order" [drivers/cpufreq/powernow-k6.ko] undefined! > > Add a 'static' definition so any file in which this happens can > have a local copy. > > Signed-off-by: Arnd Bergmann <a...@arndb.de>
Hi, what is the status of this patch? I needed this one to be able to build VirtualBox via DKMS as an out-of-tree kernel-module. Package: virtualbox-dkms version 6.1.12-dfsg-8 (Debian/unstable) To quote myself (see [1]): Passing LLVM_IAS=1 results in: AR /var/lib/dkms/virtualbox/6.1.12/build/built-in.a MODPOST /var/lib/dkms/virtualbox/6.1.12/build/Module.symvers ERROR: modpost: "__force_order" [/var/lib/dkms/virtualbox/6.1.12/build/vboxdrv/vboxdrv.ko] undefined! Arnd's patch is mandatory to build with Clang's Integrated Assembler (make LLVM_IAS=1). Here: LLVM toolchain version 11.0.0-rc1 Feel free to add: Reported-by: Sedat Dilek <sedat.di...@gmail.com> Tested-by: Sedat Dilek <sedat.di...@gmail.com> Can one of the tip maintainers pick this up, please? Thanks. Regards, - Sedat - [1] https://github.com/ClangBuiltLinux/linux/issues/1104#issuecomment-667470053 > --- > arch/x86/boot/compressed/pgtable_64.c | 2 ++ > arch/x86/include/asm/special_insns.h | 7 +++++++ > 2 files changed, 9 insertions(+) > > diff --git a/arch/x86/boot/compressed/pgtable_64.c > b/arch/x86/boot/compressed/pgtable_64.c > index c8862696a47b..8595194cea41 100644 > --- a/arch/x86/boot/compressed/pgtable_64.c > +++ b/arch/x86/boot/compressed/pgtable_64.c > @@ -12,7 +12,9 @@ > * It is not referenced from the code, but GCC < 5 with -fPIE would fail > * due to an undefined symbol. Define it to make these ancient GCCs work. > */ > +#ifndef CONFIG_CC_IS_CLANG > unsigned long __force_order; > +#endif > > #define BIOS_START_MIN 0x20000U /* 128K, less than this is > insane */ > #define BIOS_START_MAX 0x9f000U /* 640K, absolute maximum */ > diff --git a/arch/x86/include/asm/special_insns.h > b/arch/x86/include/asm/special_insns.h > index 82436cb04ccf..7081e587c1ea 100644 > --- a/arch/x86/include/asm/special_insns.h > +++ b/arch/x86/include/asm/special_insns.h > @@ -16,8 +16,15 @@ > * A memory clobber would solve the problem, but would prevent reordering of > * all loads stores around it, which can hurt performance. Solution is to > * use a variable and mimic reads and writes to it to enforce serialization > + * > + * Clang sometimes fails to kill the reference to the dummy variable, so > + * provide an actual copy. > */ > +#ifdef CONFIG_CC_IS_CLANG > +static unsigned long __force_order; > +#else > extern unsigned long __force_order; > +#endif > > void native_write_cr0(unsigned long val); > > -- > 2.26.2 > > -- > You received this message because you are subscribed to the Google Groups > "Clang Built Linux" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to clang-built-linux+unsubscr...@googlegroups.com. > To view this discussion on the web visit > https://groups.google.com/d/msgid/clang-built-linux/20200527135329.1172644-1-arnd%40arndb.de.
