From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751547AbbALVSK (ORCPT ); Mon, 12 Jan 2015 16:18:10 -0500 Received: from cantor2.suse.de ([195.135.220.15]:55711 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751107AbbALVSJ (ORCPT ); Mon, 12 Jan 2015 16:18:09 -0500 Date: Mon, 12 Jan 2015 22:18:02 +0100 From: Borislav Petkov To: riel@redhat.com Cc: linux-kernel@vger.kernel.org, mingo@redhat.com, hpa@zytor.com, matt.fleming@intel.com, oleg@redhat.com, pbonzini@redhat.com, tglx@linutronix.de, luto@amacapital.net Subject: Re: [RFC PATCH 01/11] x86,fpu: document the data structures a little Message-ID: <20150112211802.GE5016@pd.tnic> References: <1421012793-30106-1-git-send-email-riel@redhat.com> <1421012793-30106-2-git-send-email-riel@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <1421012793-30106-2-git-send-email-riel@redhat.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, Jan 11, 2015 at 04:46:23PM -0500, riel@redhat.com wrote: > From: Rik van Riel > > Add some documentation to data structures used for FPU context > switching. > > Signed-off-by: Rik van Riel > --- > 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. --