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Groups > linux.kernel > #1623440
| From | "H. Peter Anvin" <hpa@zytor.com> |
|---|---|
| Newsgroups | linux.kernel |
| Subject | Re: [PATCH 3/7] x86, LLVM: suppress clang warnings about unaligned accesses |
| Date | 2017-04-14 02:00 +0200 |
| Message-ID | <tvWOB-1Nu-3@gated-at.bofh.it> (permalink) |
| References | <tlNWh-6eK-9@gated-at.bofh.it> <tlNWh-6eK-7@gated-at.bofh.it> <tm9WN-5YC-7@gated-at.bofh.it> <tsjgJ-4ZI-13@gated-at.bofh.it> <tvWbU-1xv-7@gated-at.bofh.it> |
| Organization | linux.* mail to news gateway |
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@zytor.com ha dit: >> >>> On March 16, 2017 5:15:16 PM PDT, Michael Davidson <md@google.com> 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@google.com> >>>> --- >>>> 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. -hpa
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Re: [PATCH 3/7] x86, LLVM: suppress clang warnings about unaligned accesses Matthias Kaehlcke <mka@chromium.org> - 2017-04-14 01:20 +0200
Re: [PATCH 3/7] x86, LLVM: suppress clang warnings about unaligned accesses "H. Peter Anvin" <hpa@zytor.com> - 2017-04-14 02:00 +0200
Re: [PATCH 3/7] x86, LLVM: suppress clang warnings about unaligned accesses Matthias Kaehlcke <mka@chromium.org> - 2017-04-14 02:30 +0200
Re: [PATCH 3/7] x86, LLVM: suppress clang warnings about unaligned accesses hpa@zytor.com - 2017-04-14 07:40 +0200
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