From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Date: Sat, 17 Jun 2006 06:58:39 +0000 Subject: Re: FOR REVIEW: New x86-64 vsyscall vgetcpu() Message-Id: <200606170858.39656.ak@suse.de> List-Id: References: <200606140942.31150.ak@suse.de> <20060616181940.S91827@pkunk.americas.sgi.com> In-Reply-To: <20060616181940.S91827@pkunk.americas.sgi.com> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Brent Casavant Cc: Chase Venters , Zoltan Menyhart , Jes Sorensen , Tony Luck , discuss@x86-64.org, linux-kernel@vger.kernel.org, libc-alpha@sourceware.org, vojtech@suse.cz, linux-ia64@vger.kernel.org > That work could form the basis for a low-impact method of exporting > the current CPU to user space via a read-only mapped page. I'll admit > to having zero knowledge of whether this would be workable on anything > other than ia64. On x86 per CPU mappings are not really feasible. That is because the CPU uses the Linux page tables directly and to change them per CPU you would need to fork them per CPU. That would add so much complications that I don't even want to think them all through ... -andi