From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (qmail 25833 invoked by alias); 16 Oct 2008 16:54:39 -0000 Received: (qmail 25362 invoked by uid 48); 16 Oct 2008 16:53:25 -0000 Date: Thu, 16 Oct 2008 16:54:00 -0000 Message-ID: <20081016165325.25361.qmail@sourceware.org> From: "sjmunroe at us dot ibm dot com" To: glibc-bugs@sources.redhat.com In-Reply-To: <20080804175727.6816.cseo@linux.vnet.ibm.com> References: <20080804175727.6816.cseo@linux.vnet.ibm.com> Reply-To: sourceware-bugzilla@sourceware.org Subject: [Bug libc/6816] Support for POWER7 VSX registers in *context routines X-Bugzilla-Reason: CC Mailing-List: contact glibc-bugs-help@sourceware.org; run by ezmlm Precedence: bulk List-Id: List-Subscribe: List-Post: List-Help: , Sender: glibc-bugs-owner@sourceware.org X-SW-Source: 2008-10/txt/msg00041.txt.bz2 ------- Additional Comments From sjmunroe at us dot ibm dot com 2008-10-16 16:53 ------- >> We want to allow user space applications continued API access to the context via >> the get/set/swap context interface to the new VSX aware swapcontext syscall. >The context shouldn't contain the new registers, that's the point. The *context >functions are function calls. Hence registers which are not preserved don't >have to be included in the context data structures. This eliminates the >versioning problem and it is exactly the way this is handled on x86. That is true for getcontext but may not be true for set/swapcontext depending on the source of the context (ie. signal frames). So it seem like the setcontext and the kernels swapcontext syscall should handle the larger context size. There is a separate question if the size_of(ucontext_t) includes the VSX state or not. If as you suggest (this time) we can avoid the versioning for the user state functions as long as the kernel swapcontext syscall recognizes that for MSR:VSX =1 the context is a the bigger size. This would be the case for a signal ucontext in an application using VSX. It follows that for getcontext we only pass the current size and the kernel does not set MSR:VSX even if VSX is use (because the new VSX state is volatile!). -- http://sourceware.org/bugzilla/show_bug.cgi?id=6816 ------- You are receiving this mail because: ------- You are on the CC list for the bug, or are watching someone who is.