From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1764028AbYETSB7 (ORCPT ); Tue, 20 May 2008 14:01:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755869AbYETSBv (ORCPT ); Tue, 20 May 2008 14:01:51 -0400 Received: from terminus.zytor.com ([198.137.202.10]:35709 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755943AbYETSBu (ORCPT ); Tue, 20 May 2008 14:01:50 -0400 Message-ID: <483310F0.5030902@zytor.com> Date: Tue, 20 May 2008 10:57:04 -0700 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.14 (X11/20080501) MIME-Version: 1.0 To: Mikael Pettersson CC: Andi Kleen , Suresh Siddha , mingo@elte.hu, tglx@linutronix.de, torvalds@linux-foundation.org, akpm@linux-foundation.org, roland@redhat.com, drepper@redhat.com, Hongjiu.lu@intel.com, linux-kernel@vger.kernel.org, arjan@linux.intel.com, rmk+lkml@arm.linux.org.uk, dan@debian.org, asit.k.mallick@intel.com Subject: Re: [RFC] x86: xsave/xrstor support, ucontext_t extensions References: <20080513011030.GA31448@linux-os.sc.intel.com> <18477.35703.679574.760417@harpo.it.uu.se> <20080518013416.GB30034@linux-os.sc.intel.com> <18481.37905.297556.288317@harpo.it.uu.se> <20080520015723.GD30034@linux-os.sc.intel.com> <4832A173.6020203@firstfloor.org> <18482.53246.642835.894623@harpo.it.uu.se> <4832E705.2010900@zytor.com> <18482.60491.764019.292031@harpo.it.uu.se> In-Reply-To: <18482.60491.764019.292031@harpo.it.uu.se> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Mikael Pettersson wrote: > > An ugly workaround could be to start clearing one of these fields, > and say that the data there is only valid for kernels >= 2.6.26. > (I said it was ugly...) > > Or we go back to stashing a flag in uc_flags (which is kosher), > and try to figure out how to mark non-rt sigframes. > Or use the OSXSAVE hack. Let me think about this for some time. There is also the option of simply using a field guarded by a 64- or 128-bit magic number. It's a bit ugly, but it works. -hpa