From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758507AbYHVVgZ (ORCPT ); Fri, 22 Aug 2008 17:36:25 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755816AbYHVVgL (ORCPT ); Fri, 22 Aug 2008 17:36:11 -0400 Received: from smtp1.linux-foundation.org ([140.211.169.13]:53917 "EHLO smtp1.linux-foundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755255AbYHVVgJ (ORCPT ); Fri, 22 Aug 2008 17:36:09 -0400 Date: Fri, 22 Aug 2008 14:35:15 -0700 From: Andrew Morton To: Jeremy Fitzhardinge Cc: ehabkost@redhat.com, benh@kernel.crashing.org, paulus@samba.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH 1 of 3] add phys_addr_t for holding physical addresses Message-Id: <20080822143515.512ff182.akpm@linux-foundation.org> In-Reply-To: <48AF2B74.5030605@goop.org> References: <73196c9129c7298f2428.1219176170@localhost> <20080822130235.af69ccb5.akpm@linux-foundation.org> <48AF2B74.5030605@goop.org> X-Mailer: Sylpheed version 2.2.4 (GTK+ 2.8.20; i486-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, 22 Aug 2008 14:11:16 -0700 Jeremy Fitzhardinge wrote: > Andrew Morton wrote: > > On Tue, 19 Aug 2008 13:02:50 -0700 > > Jeremy Fitzhardinge wrote: > > > > > >> Add a kernel-wide "phys_addr_t" which is guaranteed to be able to hold > >> any physical address. By default it equals the word size of the > >> architecture, but a 32-bit architecture can set ARCH_PHYS_ADDR_T_64BIT > >> if it needs a 64-bit phys_addr_t. > >> > >> > > > > You say this is a bugfix but you don't describe the bug. This makes it > > rather hard to make the 2.6.2[5678] decisions. > > > > Ditto on [patch 2/3]. > > > > 1/3 is not a bugfix in itself, but a pre-requisite for 2/3. > > 2/3 replaces an ad-hoc Xen fix with a general fix to prevent address > truncation when using PFN_PHYS() on any PFN above the 4G mark. The Xen > crash is the only bug I know of that's directly attributable to this, > and it was already addressed in older kernels with the casts in the Xen > code that this patch removes. > > So I don't think there's any strong need to push this to earlier kernels. > Still confused. The above implies that 2.6.27 doesn't need fixing either, because the typecasts already avoid the crash.