From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756825Ab1FUO6X (ORCPT ); Tue, 21 Jun 2011 10:58:23 -0400 Received: from iolanthe.rowland.org ([192.131.102.54]:41472 "HELO iolanthe.rowland.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with SMTP id S1752160Ab1FUO6U (ORCPT ); Tue, 21 Jun 2011 10:58:20 -0400 Date: Tue, 21 Jun 2011 10:58:19 -0400 (EDT) From: Alan Stern X-X-Sender: stern@iolanthe.rowland.org To: Nicolas Pitre cc: Alexander Holler , Arnd Bergmann , , , , lkml , Rabin Vincent Subject: Re: [PATCH] USB: ehci: use packed,aligned(4) instead of removing the packed attribute In-Reply-To: Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, 20 Jun 2011, Nicolas Pitre wrote: > > We don't fall into any of these cases, and therefore as you say, we > > don't need packed. Arnd and I have both explained this. So why do you > > keep arguing that we do need it? > > Please show me where I keep arguing that you need it? Not explicitly perhaps. But you did write: > Doesn't mean that because it used to work that it is strictly correct. > Wouldn't be the first time that a GCC upgrade broke the kernel because > the kernel wasn't describing things properly enough. which strongly implies that "packed" is needed. You also wrote: > Yes, but that's a consequence of not being able to access those fields > in their naturally aligned position anymore. Hence the addition of the > align attribute to tell the compiler that we know that the structure is > still aligned to a certain degree letting the compiler to avoid > byte-oriented instructions when possible. which is predicated on the assumption that "packed" is needed. Alan Stern From mboxrd@z Thu Jan 1 00:00:00 1970 From: stern@rowland.harvard.edu (Alan Stern) Date: Tue, 21 Jun 2011 10:58:19 -0400 (EDT) Subject: [PATCH] USB: ehci: use packed,aligned(4) instead of removing the packed attribute In-Reply-To: Message-ID: To: linux-arm-kernel@lists.infradead.org List-Id: linux-arm-kernel.lists.infradead.org On Mon, 20 Jun 2011, Nicolas Pitre wrote: > > We don't fall into any of these cases, and therefore as you say, we > > don't need packed. Arnd and I have both explained this. So why do you > > keep arguing that we do need it? > > Please show me where I keep arguing that you need it? Not explicitly perhaps. But you did write: > Doesn't mean that because it used to work that it is strictly correct. > Wouldn't be the first time that a GCC upgrade broke the kernel because > the kernel wasn't describing things properly enough. which strongly implies that "packed" is needed. You also wrote: > Yes, but that's a consequence of not being able to access those fields > in their naturally aligned position anymore. Hence the addition of the > align attribute to tell the compiler that we know that the structure is > still aligned to a certain degree letting the compiler to avoid > byte-oriented instructions when possible. which is predicated on the assumption that "packed" is needed. Alan Stern