On April 13, 2017 5:23:35 PM PDT, Matthias Kaehlcke <mka@xxxxxxxxxxxx> wrote: >El Thu, Apr 13, 2017 at 04:55:00PM -0700 H. Peter Anvin ha dit: > >> On 04/13/17 16:14, Matthias Kaehlcke wrote: >> > El Mon, Apr 03, 2017 at 04:01:58PM -0700 Matthias Kaehlcke ha dit: >> > >> >> El Fri, Mar 17, 2017 at 04:50:19PM -0700 hpa@xxxxxxxxx ha dit: >> >> >> >>> On March 16, 2017 5:15:16 PM PDT, Michael Davidson ><md@xxxxxxxxxx> wrote: >> >>>> Suppress clang warnings about potential unaliged accesses >> >>>> to members in packed structs. This gets rid of almost 10,000 >> >>>> warnings about accesses to the ring 0 stack pointer in the TSS. >> >>>> >> >>>> Signed-off-by: Michael Davidson <md@xxxxxxxxxx> >> >>>> --- >> >>>> arch/x86/Makefile | 5 +++++ >> >>>> 1 file changed, 5 insertions(+) >> >>>> >> >>>> diff --git a/arch/x86/Makefile b/arch/x86/Makefile >> >>>> index 894a8d18bf97..7f21703c475d 100644 >> >>>> --- a/arch/x86/Makefile >> >>>> +++ b/arch/x86/Makefile >> >>>> @@ -128,6 +128,11 @@ endif >> >>>> KBUILD_CFLAGS += $(call >cc-option,-maccumulate-outgoing-args) >> >>>> endif >> >>>> >> >>>> +ifeq ($(cc-name),clang) >> >>>> +# Suppress clang warnings about potential unaligned accesses. >> >>>> +KBUILD_CFLAGS += $(call cc-disable-warning, >address-of-packed-member) >> >>>> +endif >> >>>> + >> >>>> ifdef CONFIG_X86_X32 >> >>>> x32_ld_ok := $(call try-run,\ >> >>>> /bin/echo -e '1: .quad 1b' | \ >> >>> >> >>> Why conditional on clang? >> >> >> >> My understanding is that this warning is clang specific, it is not >> >> listed on https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html >> > >> > Actually this warning affects other platforms besides x86 >> > (e.g. arm64), I'll submit a patch that disables the warning on all >> > platforms. >> > >> >> Drop the ifeq ($(cc-name),clang). >> >> You should assume that if you have to add one of those ifeq's then >you >> are doing something fundamentally wrong. > >Thanks, however in the case of the global Makefile it seems we should >put it inside the already existing clang section: > >http://lxr.free-electrons.com/source/Makefile#L692 > >Cheers > >Matthias We shouldn't, unless it will actively break non-clang builds... -- Sent from my Android device with K-9 Mail. Please excuse my brevity. -- To unsubscribe from this list: send the line "unsubscribe linux-kbuild" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
