Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id ; Wed, 2 Jan 2002 17:35:06 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id ; Wed, 2 Jan 2002 17:34:00 -0500 Received: from mailrelay1.lrz-muenchen.de ([129.187.254.101]:33520 "EHLO mailrelay1.lrz-muenchen.de") by vger.kernel.org with ESMTP id ; Wed, 2 Jan 2002 17:32:51 -0500 Date: Wed, 2 Jan 2002 23:32:45 +0100 (MET) From: X-X-Sender: To: Jens Axboe cc: David Brownell , , , Matthew Dharm , Greg KH Subject: Re: [linux-usb-devel] Re: highmem and usb [was "sr: unalignedtransfer" in 2.5.2-pre1] In-Reply-To: <20020102194404.A482@suse.de> Message-Id: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2 Jan 2002, Jens Axboe wrote: > On Wed, Jan 02 2002, David Brownell wrote: > > > > requirement for drivers is that the transfer buffers can be passed to > > > > pci_map_single() calls by the Host Controller Drivers (HCDs). The > > > > device drivers, and URBs, don't expose such mappings, they only > > > > require that they can be created/destroyed. > > > > > > .. which is the requirement that you want to change to use pci_map_page > > > or pci_map_sg > > > > OK, I think I'm clear on this much then: in 2.5, to support block drivers > > over USB (usb-storage only, for now) there needs to be an addition to > > the buffer addressing model in usbcore, as exposed by URBs. > > > > - Current "transfer_buffer" + "transfer_buffer_length" mode needs to > > stay, since most drivers aren't block drivers. > > Why? Surely USB block drivers are not the only ones that want to support > highmem. Probably for a long time they'll be the only ones. All the char drivers will mainly do a copy_to/from_user or want memory they can manipulate directly. Regards Oliver - 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/