From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S967155Ab0GSXIT (ORCPT ); Mon, 19 Jul 2010 19:08:19 -0400 Received: from mga02.intel.com ([134.134.136.20]:49884 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S966620Ab0GSXIS (ORCPT ); Mon, 19 Jul 2010 19:08:18 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.55,229,1278313200"; d="scan'208";a="536998394" Message-Id: <20100719225747.372816924@sbs-t61.sc.intel.com> User-Agent: quilt/0.47-1 Date: Mon, 19 Jul 2010 16:05:47 -0700 From: Suresh Siddha To: "H. Peter Anvin" , Ingo Molnar , Thomas Gleixner Cc: LKML , Suresh Siddha Subject: [patch 0/5] x86: xsaveopt kernel enabling patches - v2 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org AVX Programming Reference (June, 2010 version) located at http://software.intel.com/en-us/avx/ refers to the optimized extended state save instruction "xsaveopt". xsaveopt is similar to xsave and incorporates optimizations specifically targeted for speeding up context switch save, like: a. if a state is in an INIT state, the instruction may clear the corresponding bit in the xheader.bv with out writing the actual state in to the memory. b. if the state hasn't been modified since the last xrstor, the instruction may not write out the state to the save area. Following patches enable the use of xsaveopt for context switch save/restore of the extended state. changes in v2: Split the cpu feature detection bits in to multiple patches along with the misc changes in the init_scattered_cpuid_features() -- Requested by hpa. Signed-off-by: Suresh Siddha