Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754312Ab0BHGzr (ORCPT ); Mon, 8 Feb 2010 01:55:47 -0500 Received: from atrey.karlin.mff.cuni.cz ([195.113.26.193]:39931 "EHLO atrey.karlin.mff.cuni.cz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753294Ab0BHGzp (ORCPT ); Mon, 8 Feb 2010 01:55:45 -0500 Date: Mon, 8 Feb 2010 07:55:38 +0100 From: Pavel Machek To: Alan Stern Cc: Oliver Neukum , Catalin Marinas , Matthew Dharm , Sergei Shtylyov , Ming Lei , linux-usb@vger.kernel.org, linux-kernel , Sebastian Siewior , Greg KH Subject: Re: USB mass storage and ARM cache coherency Message-ID: <20100208065537.GF1290@ucw.cz> References: <201002021408.51851.oliver@neukum.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1637 Lines: 38 On Tue 2010-02-02 12:11:25, Alan Stern wrote: > On Tue, 2 Feb 2010, Oliver Neukum wrote: > > > Am Dienstag, 2. Februar 2010 13:39:35 schrieb Catalin Marinas: > > > > For storage that is correct. But what about other sources of pages, > > > > for example iSCSI? > > > > > > In the iSCSI case, does the HCD driver write directly to a page cache > > > page? Or it just fills in network packets that are copied to page cache > > > pages by the iSCSI code (sorry, I'm not familiar with this part of the > > > kernel). If the latter, the cache flushing in the HCD driver would not > > > help and it needs to be done in the iSCSI code. > > > > As far as I can tell iSCSI does a private copy. But I don't know how > > many methods to transfer code pages over USB exist. I'd say the > > conservative solution is to flush for everything but control transfers. > > This doesn't make any sense. Nobody would ever use isochronous > transfers to store data into a code page because isochronous is > unreliable. (Audio isn't a counterexample -- audio data may be Why not? Use isochronous transfer to load data, verify it is okay, exec it. Or maybe someone is doing crashme testing with usb audio as random generator :-). Sure, unlikely, but... Pavel -- (english) http://www.livejournal.com/~pavelmachek (cesky, pictures) http://atrey.karlin.mff.cuni.cz/~pavel/picture/horses/blog.html -- 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/