Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S265044AbUIVCQU (ORCPT ); Tue, 21 Sep 2004 22:16:20 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S267708AbUIVCQU (ORCPT ); Tue, 21 Sep 2004 22:16:20 -0400 Received: from ozlabs.org ([203.10.76.45]:60093 "EHLO ozlabs.org") by vger.kernel.org with ESMTP id S265044AbUIVCQK (ORCPT ); Tue, 21 Sep 2004 22:16:10 -0400 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <16720.57400.930844.91232@cargo.ozlabs.ibm.com> Date: Tue, 21 Sep 2004 21:15:20 -0500 From: Paul Mackerras To: Linus Torvalds Cc: Roland Dreier , Benjamin Herrenschmidt , Alan Cox , Andrew Morton , Linux Kernel Mailing List , Petr Vandrovec Subject: Re: [PATCH] ppc64: Fix __raw_* IO accessors In-Reply-To: References: <1095758630.3332.133.camel@gaston> <1095761113.30931.13.camel@localhost.localdomain> <1095766919.3577.138.camel@gaston> <523c1bpghm.fsf@topspin.com> <52mzzjnuq7.fsf@topspin.com> X-Mailer: VM 7.18 under Emacs 21.3.1 Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1029 Lines: 23 Linus Torvalds writes: > I wasn't using pp64 back when, maybe there's some other reason for playing > games with the tokens? Who's the guity/knowledgeable party? Ben? I believe this was done so that we could quickly work out the pci bus/device/function inside read/write[bwl]. We needed that for coping with the "Enhanced Error Handling" (EEH) stuff on pSeries machines. I think we used to stuff the pci bus/dev/fn in the high bits and then change the top 4 bits to make quite clear that it wasn't a valid pointer. These days we don't put the pci bus/dev/fn in the high bits and we could certainly get rid of the IO_TOKEN_TO_ADDR games. This stuff predates Ben's involvement in ppc64 by a long way, and was put in before Anton or I had much influence. We'll clean it up. Paul. - 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/