Userland should use a different query mechanism. On the other hand, it will not hurt either. On pre-xsave kernels AVX is a non-option.
Ben Hutchings <[email protected]> wrote: >On Fri, 2012-09-28 at 11:51 -0700, Greg Kroah-Hartman wrote: >> From: Greg KH <[email protected]> >> >> 3.5-stable review patch. If anyone has any objections, please let me >know. >> >> ------------------ >> >> From: Suresh Siddha <[email protected]> >> >> commit c6fd893da927c6cefb2ece22402765379921a834 upstream. >> >> Clear AVX, AVX2 features along with clearing XSAVE feature bits, >> as part of the parsing "noxsave" parameter. >> >> Fixes the kernel boot panic with "noxsave" boot parameter. >> >> We could have checked cpu_has_osxsave along with cpu_has_avx etc, but >Peter >> mentioned clearing the feature bits will be better for uses like >> static_cpu_has() etc. > >This was marked as needed for 3.5 only - presumably because the kernel >wasn't using AVX before this - but don't we also need to clear these >bits even in earlier versions so userland knows not to use it? > >Ben. > >> Signed-off-by: Suresh Siddha <[email protected]> >> Link: >http://lkml.kernel.org/r/[email protected] >> Signed-off-by: H. Peter Anvin <[email protected]> >> Signed-off-by: Greg Kroah-Hartman <[email protected]> >> >> --- >> arch/x86/kernel/cpu/common.c | 2 ++ >> 1 file changed, 2 insertions(+) >> >> --- a/arch/x86/kernel/cpu/common.c >> +++ b/arch/x86/kernel/cpu/common.c >> @@ -144,6 +144,8 @@ static int __init x86_xsave_setup(char * >> { >> setup_clear_cpu_cap(X86_FEATURE_XSAVE); >> setup_clear_cpu_cap(X86_FEATURE_XSAVEOPT); >> + setup_clear_cpu_cap(X86_FEATURE_AVX); >> + setup_clear_cpu_cap(X86_FEATURE_AVX2); >> return 1; >> } >> __setup("noxsave", x86_xsave_setup); -- Sent from my mobile phone. Please excuse brevity and lack of formatting. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
