Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030298AbWA0KlM (ORCPT ); Fri, 27 Jan 2006 05:41:12 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1030299AbWA0KlL (ORCPT ); Fri, 27 Jan 2006 05:41:11 -0500 Received: from ns.virtualhost.dk ([195.184.98.160]:51009 "EHLO virtualhost.dk") by vger.kernel.org with ESMTP id S1030298AbWA0KlK (ORCPT ); Fri, 27 Jan 2006 05:41:10 -0500 Date: Fri, 27 Jan 2006 11:43:21 +0100 From: Jens Axboe To: Pierre Ossman Cc: LKML Subject: Re: How to map high memory for block io Message-ID: <20060127104321.GE4311@suse.de> References: <43D9C19F.7090707@drzeus.cx> <20060127102611.GC4311@suse.de> <43D9F705.5000403@drzeus.cx> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <43D9F705.5000403@drzeus.cx> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1749 Lines: 41 On Fri, Jan 27 2006, Pierre Ossman wrote: > Jens Axboe wrote: > > On Fri, Jan 27 2006, Pierre Ossman wrote: > > > >> I'm having some problems getting high memory support to work smoothly in > >> my driver. The documentation doesn't indicate what I might be doing > >> wrong so I'll have to ask here. > >> > >> The problem seems to be that kmap & co maps a single page into kernel > >> memory. So when I happen to cross page boundaries I start corrupting > >> some unrelated parts of the kernel. I would prefer not having to > >> consider page boundaries in an already messy PIO loop, so I've been > >> trying to find either a routine to map an entire sg entry or some way to > >> force the block layer to not give me stuff crossing pages. > >> > >> As you can guess I have not found anything that can do what I want, so > >> some pointers would be nice. > >> > > > > Honestly, just don't bother if you are doing PIO anyways. Just tell the > > block layer that you want io bounced for you instead. > > > > > > This is the MMC layer so there is some separation between the block > layer and the drivers. Also, the transfers won't necessarily be from the > block layer so a generic solution is desired. I don't suppose there is > some way of accessing the bounce buffer routines in a non-bio context? Only the mapping routines are appropriate at that point, or things get complicated. You could still do a two-page mapping, if you are careful about using different KMAP_ types. -- Jens Axboe - 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/