Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753678AbYLRVtv (ORCPT ); Thu, 18 Dec 2008 16:49:51 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752243AbYLRVtm (ORCPT ); Thu, 18 Dec 2008 16:49:42 -0500 Received: from mga01.intel.com ([192.55.52.88]:19045 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752174AbYLRVtm (ORCPT ); Thu, 18 Dec 2008 16:49:42 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.36,245,1228118400"; d="scan'208";a="650978906" Date: Thu, 18 Dec 2008 13:49:41 -0800 From: "Pallipadi, Venkatesh" To: Randy Dunlap Cc: "Pallipadi, Venkatesh" , "mingo@elte.hu" , "tglx@linutronix.de" , "hpa@zytor.com" , "akpm@linux-foundation.org" , "npiggin@suse.de" , "hugh@veritas.com" , "arjan@infradead.org" , "jbarnes@virtuousgeek.org" , "rdreier@cisco.com" , "jeremy@goop.org" , "linux-kernel@vger.kernel.org" , "Siddha, Suresh B" Subject: Re: [patch 7/7] x86 PAT: update documentation to cover pgprot and remap_pfn related changes - v3 Message-ID: <20081218214940.GA31088@linux-os.sc.intel.com> References: <20081218194126.963894000@intel.com> <20081218194617.987565000@intel.com> <494ABCF8.8050802@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <494ABCF8.8050802@oracle.com> User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3431 Lines: 98 On Thu, Dec 18, 2008 at 01:13:28PM -0800, Randy Dunlap wrote: > venkatesh.pallipadi@intel.com wrote: > > +Advanced APIs for drivers > +------------------------- > +A. Exporting pages to user with remap_pfn_range, io_remap_pfn_range, > > to users > or to userspace > > +vm_insert_pfn > + > +Drivers wanting to export some pages to userspace, do it by using mmap > > Drop comma. > > +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 > > s/pat/PAT/ > s/driver/drivers/ or s/driver/a driver/ > > +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 > > works with IO (non-RAM) regions. If a driver > > +wants to export RAM region, it has to do set_memory_uc() or set_memory_wc() > > export a RAM region, > > +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. > > refreshed patch below Thanks, Venki 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: linux-2.6/Documentation/x86/pat.txt =================================================================== --- linux-2.6.orig/Documentation/x86/pat.txt 2008-12-17 15:01:50.000000000 -0800 +++ linux-2.6/Documentation/x86/pat.txt 2008-12-17 17:23:16.000000000 -0800 @@ -80,6 +80,30 @@ pci proc | -- | - | | | | ------------------------------------------------------------------- +Advanced APIs for drivers +------------------------- +A. Exporting pages to users 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, drivers 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 a driver +wants to export a 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 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/