Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753701AbYGIUI7 (ORCPT ); Wed, 9 Jul 2008 16:08:59 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752145AbYGIUIv (ORCPT ); Wed, 9 Jul 2008 16:08:51 -0400 Received: from smtp-vbr7.xs4all.nl ([194.109.24.27]:2268 "EHLO smtp-vbr7.xs4all.nl" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751502AbYGIUIu (ORCPT ); Wed, 9 Jul 2008 16:08:50 -0400 Subject: Re: [PATCH] Mark i2o config broken on 64-bit platforms. From: Miquel van Smoorenburg To: James Bottomley Cc: Alan Cox , David Howells , akpm@linux-foundation.org, alan@redhat.com, Markus.Lidel@shadowconnect.com, vvs@sw.ru, linux-kernel@vger.kernel.org, linux-scsi@vger.kernel.org In-Reply-To: <1215633595.3444.18.camel@localhost.localdomain> References: <20080709113547.19235.15424.stgit@warthog.procyon.org.uk> <4561.1215612914@redhat.com> <20080709164929.799e4e05@the-village.bc.nu> <1215630402.18506.10.camel@localhost.localdomain> <1215630817.3444.16.camel@localhost.localdomain> <1215631336.18506.15.camel@localhost.localdomain> <1215633595.3444.18.camel@localhost.localdomain> Content-Type: text/plain Date: Wed, 09 Jul 2008 22:06:52 +0200 Message-Id: <1215634012.18506.21.camel@localhost.localdomain> Mime-Version: 1.0 X-Mailer: Evolution 2.22.2 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2444 Lines: 55 On Wed, 2008-07-09 at 14:59 -0500, James Bottomley wrote: > On Wed, 2008-07-09 at 21:22 +0200, Miquel van Smoorenburg wrote: > > On Wed, 2008-07-09 at 14:13 -0500, James Bottomley wrote: > > > On Wed, 2008-07-09 at 21:06 +0200, Miquel van Smoorenburg wrote: > > > > On Wed, 2008-07-09 at 16:49 +0100, Alan Cox wrote: > > > > > On Wed, 09 Jul 2008 15:15:14 +0100 > > > > > David Howells wrote: > > > > > > > > > > > Miquel van Smoorenburg wrote: > > > > > > Maybe, but have you looked at i2o_cfg_passthru()? Take this, for example: > > > > > > > > > > > > /* Allocate memory for the transfer */ > > > > > > p = kmalloc(sg_size, GFP_KERNEL); > > > > > > ... > > > > > > //TODO 64bit fix > > > > > > sg[i].addr_bus = virt_to_bus(p); > > > > > > > > > > > > That looks distinctly dodgy. virt_to_bus() returns a 64-bit address, and as > > > > > > > > > > Agreed - stick | GFP_DMA32 on the end then ;) > > > > > > > > GFP_DMA32 doesn't work with kmalloc(), you need dma_alloc_coherent() or > > > > pci_alloc_consistent() [here, i2o_dma_alloc() ] > > > > > > Yes it does ... it was specifically designed for it. GFP_DMA32 was > > > introduced to allow this type of thing to happen (in the old days most > > > drivers were allowed to assume kmalloc would return memory whose > > > physical address was < 4GB; GFP_DMA32 allows that to continue while > > > allowing kmalloc to stray beyond 4GB physical). > > > > If you use alloc_pages(), yes. But not for kmalloc(). There are no > > general GFP_DMA32 slabs. > > No ... it's platform specific. Platforms whose ZONE_NORMAL covers only > up to 4GB need do nothing. However, x86_64 definitely implements > ZONE_DMA32 for precisely this. Several other platforms (like ia64) > should but don't. I tried using it before (for dpt_i2o.c) and it didn't work. I re-read quite a bit of kernel code before I posted this, and I could not find GFP_DMA32 slabs. There are also no calls to kmalloc(size, GFP_...|GFP_DMA32) in the recent kernels I checked. And google tells me things like http://lkml.org/lkml/2007/5/17/267 So I don't think GFP_DMA32 works with kmalloc. GFP_DMA does though. Mike. -- 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/