From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1757283AbYHBPm3 (ORCPT ); Sat, 2 Aug 2008 11:42:29 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1754023AbYHBPmW (ORCPT ); Sat, 2 Aug 2008 11:42:22 -0400 Received: from terminus.zytor.com ([198.137.202.10]:38436 "EHLO terminus.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753772AbYHBPmV (ORCPT ); Sat, 2 Aug 2008 11:42:21 -0400 Message-ID: <4894800F.40802@zytor.com> Date: Sat, 02 Aug 2008 08:41:03 -0700 From: "H. Peter Anvin" User-Agent: Thunderbird 2.0.0.14 (X11/20080501) MIME-Version: 1.0 To: "Eric W. Biederman" CC: Yinghai Lu , Ingo Molnar , Thomas Gleixner , Dhaval Giani , Mike Travis , Andrew Morton , linux-kernel@vger.kernel.org Subject: Re: [PATCH 00/16] dyn_array and nr_irqs support v2 References: <1217583464-28494-1-git-send-email-yhlu.kernel@gmail.com> <86802c440808011430i6cf5cb8cn519777a78dd987b0@mail.gmail.com> <86802c440808011809t275aa511h4a1e9d70ede21702@mail.gmail.com> <86802c440808011901w2aa40b25u45f5686b262cc2aa@mail.gmail.com> <4893C066.60401@zytor.com> <4893D459.4030209@zytor.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Eric W. Biederman wrote: > > Yes. I want the option of using those bits. It might not be smart to > use them to encode a physical location and the irq number but just > having the option would be nice. > Urk! First of all, there isn't enough space as we have already proven (on the machines where it actually matters there just aren't enough bits), but doing this kind of stuff *optionally* is going to hurt even worse. Furthermore, this crap will break anyway the *next* time someone comes up with a new clever way to do interrupts -- and to truly get stable identifiers, we can't treat HyperTransport MSI as APICs anymore, yadda, yadda... > Making /proc/interrupts useful without breaking user space is going to be > an interesting challenge one of these days. If changing to non-numbers in /proc/interrupts will break userspace, then userspace will have to deal with a numeric token in /proc/interrupts which will have to be looked up elsewhere (perhaps in a sysfs directory) to get a more meaningful index. -hpa