* Dave Hansen <[email protected]> wrote:
>
> From: Dave Hansen <[email protected]>
>
> I don't think it is really possible to have a system where CPUID
> enumerates support for XSAVE but that it does not have FP/SSE
> (they are "legacy" features and always present).
>
> But, I did manage to hit this case in qemu when I enabled its
> somewhat shaky XSAVE support. The bummer is that the FPU is set
> up before we parse the command-line or have *any* console support
> including earlyprintk.
>
> So a BUG() here is worthless. All it does it guarantee that
> if/when we hit this case we have an empty console. So, remove
> the BUG() and try to limp along by disabling XSAVE and trying to
> continue.
>
> Signed-off-by: Dave Hansen <[email protected]>
> ---
>
> b/arch/x86/kernel/fpu/xstate.c | 3 ++-
> 1 file changed, 2 insertions(+), 1 deletion(-)
>
> diff -puN arch/x86/kernel/fpu/xstate.c~x86-fpu-do-not-BUG_ON-early
> arch/x86/kernel/fpu/xstate.c
> --- a/arch/x86/kernel/fpu/xstate.c~x86-fpu-do-not-BUG_ON-early
> 2016-07-20 09:03:07.347941392 -0700
> +++ b/arch/x86/kernel/fpu/xstate.c 2016-07-20 09:17:15.001309137 -0700
> @@ -715,7 +715,8 @@ void __init fpu__init_system_xstate(void
>
> if ((xfeatures_mask & XFEATURE_MASK_FPSSE) != XFEATURE_MASK_FPSSE) {
> pr_err("x86/fpu: FP/SSE not present amongst the CPU's xstate
> features: 0x%llx.\n", xfeatures_mask);
> - BUG();
> + fpu__init_disable_system_xstate();
> + return;
Ok, but please put a comment there explaining why we are not stopping the
system.
Thanks,
Ingo
