Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Tue, 6 Feb 2001 20:06:32 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Tue, 6 Feb 2001 20:06:22 -0500 Received: from vger.timpanogas.org ([207.109.151.240]:2834 "EHLO vger.timpanogas.org") by vger.kernel.org with ESMTP id ; Tue, 6 Feb 2001 20:06:08 -0500 Date: Tue, 6 Feb 2001 19:00:50 -0700 From: "Jeff V. Merkey" To: Jens Axboe Cc: Linus Torvalds , "Stephen C. Tweedie" , Ingo Molnar , Ben LaHaise , Alan Cox , Manfred Spraul , Steve Lord , Linux Kernel List , kiobuf-io-devel@lists.sourceforge.net Subject: Re: [Kiobuf-io-devel] RFC: Kernel mechanism: Compound event wait Message-ID: <20010206190050.B23960@vger.timpanogas.org> In-Reply-To: <20010207003629.M1167@redhat.com> <20010206185115.A23754@vger.timpanogas.org> <20010207020221.B13647@suse.de> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-Mailer: Mutt 1.0.1i In-Reply-To: <20010207020221.B13647@suse.de>; from axboe@suse.de on Wed, Feb 07, 2001 at 02:02:21AM +0100 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 07, 2001 at 02:02:21AM +0100, Jens Axboe wrote: > On Tue, Feb 06 2001, Jeff V. Merkey wrote: > > I remember Linus asking to try this variable buffer head chaining > > thing 512-1024-512 kind of stuff several months back, and mixing them to > > see what would happen -- result. About half the drivers break with it. > > The interface allows you to do it, I've tried it, (works on Andre's > > drivers, but a lot of SCSI drivers break) but a lot of drivers seem to > > have assumptions about these things all being the same size in a > > buffer head chain. > > I don't see anything that would break doing this, in fact you can > do this as long as the buffers are all at least a multiple of the > block size. All the drivers I've inspected handle this fine, noone > assumes that rq->bh->b_size is the same in all the buffers attached > to the request. This includes SCSI (scsi_lib.c builds sg tables), > IDE, and the Compaq array + Mylex driver. This mostly leaves the > "old-style" drivers using CURRENT etc, the kernel helpers for these > handle it as well. > > So I would appreciate pointers to these devices that break so we > can inspect them. > > -- > Jens Axboe Adaptec drivers had an oops. Also, AIC7XXX also had some oops with it. Jeff - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org Please read the FAQ at http://www.tux.org/lkml/