| Date | Mon, 12 Jan 2015 22:18:02 +0100 | From | Borislav Petkov <> | Subject | Re: [RFC PATCH 01/11] x86,fpu: document the data structures a little |
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On Sun, Jan 11, 2015 at 04:46:23PM -0500, riel@redhat.com wrote: > From: Rik van Riel <riel@redhat.com> > > Add some documentation to data structures used for FPU context > switching. > > Signed-off-by: Rik van Riel <riel@redhat.com> > --- > arch/x86/include/asm/processor.h | 9 +++++++-- > arch/x86/kernel/cpu/common.c | 1 + > 2 files changed, 8 insertions(+), 2 deletions(-) > > diff --git a/arch/x86/include/asm/processor.h b/arch/x86/include/asm/processor.h > index a092a0c..17bd8a0 100644 > --- a/arch/x86/include/asm/processor.h > +++ b/arch/x86/include/asm/processor.h > @@ -400,6 +400,11 @@ struct xsave_struct { > /* new processor state extensions will go here */ > } __attribute__ ((packed, aligned (64))); > > +/* > + * The FPU state used depends on the capabilities of the hardware; the > + * registers used for vector instructions on newer hardware are included > + * in the FPU state. > + */ > union thread_xstate { > struct i387_fsave_struct fsave; > struct i387_fxsave_struct fxsave; > @@ -408,8 +413,8 @@ union thread_xstate { > }; > > struct fpu { > - unsigned int last_cpu; > - unsigned int has_fpu; > + unsigned int last_cpu; /* FPU state last loaded on this CPU */
Isn't that the last CPU which had the FPU?
> + unsigned int has_fpu; /* FPU state in current use on CPU */
I understand ->has_fpu as this thread has the FPU. See comment over user_has_fpu().
-- Regards/Gruss, Boris.
Sent from a fat crate under my desk. Formatting is fine. --
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