Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754036AbYKSPCQ (ORCPT ); Wed, 19 Nov 2008 10:02:16 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753432AbYKSPCA (ORCPT ); Wed, 19 Nov 2008 10:02:00 -0500 Received: from pasmtpb.tele.dk ([80.160.77.98]:32874 "EHLO pasmtpB.tele.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753417AbYKSPB7 (ORCPT ); Wed, 19 Nov 2008 10:01:59 -0500 Date: Wed, 19 Nov 2008 16:00:10 +0100 From: Jens Axboe To: Alan Stern Cc: Sebastian Andrzej Siewior , "Hommel, Thomas (GE EntSol, Intelligent Platforms)" , USB list , Kernel development list Subject: Re: ISP1760 driver crashes Message-ID: <20081119150010.GK26308@kernel.dk> References: <4923F120.6000303@linutronix.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2014 Lines: 47 On Wed, Nov 19 2008, Alan Stern wrote: > On Wed, 19 Nov 2008, Sebastian Andrzej Siewior wrote: > > > Hommel, Thomas (GE EntSol, Intelligent Platforms) wrote: > > > > > I indeed have HIGHMEM enabled in my configuration. > > > I recompiled the kernel without HIGHMEM and it works. I don't think that > > > this a satisfying solution for a board with up to 2GB of RAM and > > > considerable amount of VMALLOC space, but at least this works. > > > If you have any more ideas how to circumvent this, please let me know. > > Sure, this is not a sollution but atleast now I know what happens: > > - The kernel allocates memory for transfer > > - the memory is highmem and not in kernel so the buffer is NULL > > - we don't have a dma-mask and therefore the dma address is 0 > > - boom > > > > The sollution would be probably to prevent the usb-storage core to > > allocate memory from HIGHMEM. > > usb-storage doesn't allocate the memory. The memory is allocated by > the block layer or the filesystem. > > > Now I don't if there is a flag for something > > like that and I am not using that. On the other hand this may be broken > > for a long time and you are the first one which has that much memory with > > no DMA-capable USB controller. > > Jens, is there any way to tell the kernel that a device uses PIO and > therefore its buffers shouldn't be allocated in high memory? For > example, shouldn't a NULL dma_mask do this? Sure, just use blk_queue_bounce_limit(q, BLK_BOUNCE_HIGH), then you are certain that you will always have a virtual mapping for the IO you receive. Or you can use the bio kmap/kunmap helpers to get such a mapping temporarily if you wish. But if your pio condition is permanent, you may as well just use bouncing. -- 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/