From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756708AbYKLXXx (ORCPT ); Wed, 12 Nov 2008 18:23:53 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755870AbYKLXUT (ORCPT ); Wed, 12 Nov 2008 18:20:19 -0500 Received: from mga14.intel.com ([143.182.124.37]:4164 "EHLO mga14.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755833AbYKLXUM (ORCPT ); Wed, 12 Nov 2008 18:20:12 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.33,592,1220252400"; d="scan'208";a="75121296" Message-Id: <20081112212900.999435000@intel.com> References: <20081112212647.259698000@intel.com> User-Agent: quilt/0.46-1 Date: Wed, 12 Nov 2008 13:26:55 -0800 From: Venkatesh Pallipadi To: Ingo Molnar , Thomas Gleixner , H Peter Anvin , Nick Piggin , Hugh Dickins , Roland Dreier , Jesse Barnes , Jeremy Fitzhardinge , Arjan van de Ven Cc: linux-kernel@vger.kernel.org, Venkatesh Pallipadi , Suresh Siddha Subject: [patch 8/8] x86 PAT: update documentation to cover pgprot and remap_pfn related changes Content-Disposition: inline; filename=documentation_update.patch Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Add documentation related to pgprot_* change. Signed-off-by: Venkatesh Pallipadi Signed-off-by: Suresh Siddha --- Documentation/x86/pat.txt | 24 ++++++++++++++++++++++++ 1 file changed, 24 insertions(+) Index: tip/Documentation/x86/pat.txt =================================================================== --- tip.orig/Documentation/x86/pat.txt 2008-11-06 09:44:10.000000000 -0800 +++ tip/Documentation/x86/pat.txt 2008-11-06 16:19:05.000000000 -0800 @@ -80,6 +80,30 @@ pci proc | -- | - | | | | ------------------------------------------------------------------- +Advanced APIs for drivers +------------------------- +A. Exporting pages to user with remap_pfn_range, io_remap_pfn_range, +vm_insert_pfn + +Drivers wanting to export some pages to userspace, do it by using mmap +interface and a combination of +1) pgprot_noncached() +2) io_remap_pfn_range() or remap_pfn_range() or vm_insert_pfn() + +With pat support, a new API pgprot_writecombine is being added. So, driver can +continue to use the above sequence, with either pgprot_noncached() or +pgprot_writecombine() in step 1, followed by step 2. + +In addition, step 2 internally tracks the region as UC or WC in memtype +list in order to ensure no conflicting mapping. + +Note that this set of APIs only work with IO (non RAM) regions. If driver +wants to export RAM region, it has to do set_memory_uc() or set_memory_wc() +as step 0 above and also track the usage of those pages and use set_memory_wb() +before the page is freed to free pool. + + + Notes: -- in the above table mean "Not suggested usage for the API". Some of the --'s --