From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753268AbaJ0MoP (ORCPT ); Mon, 27 Oct 2014 08:44:15 -0400 Received: from mail-wg0-f47.google.com ([74.125.82.47]:45880 "EHLO mail-wg0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751907AbaJ0MoN (ORCPT ); Mon, 27 Oct 2014 08:44:13 -0400 Date: Mon, 27 Oct 2014 13:44:09 +0100 From: Ingo Molnar To: "Maciej W. Rozycki" Cc: Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , x86@kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] x86: Fix XT-PIC-XT-PIC in /proc/interrupts Message-ID: <20141027124409.GA22947@gmail.com> References: <20141027074748.GA18025@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Maciej W. Rozycki wrote: > On Mon, 27 Oct 2014, Ingo Molnar wrote: > > > What's the effect of this change on the output for non-8259A irq > > controllers? > > Good question, I didn't expect any other IRQ controller to be used for > ISA interrupts (the APIC is handled elsewhere). I have checked the > sources and the only other controller that can be used for `legacy_pic' > is `dummy_irq_chip' (cf. `default_legacy_pic' vs `null_legacy_pic' in > arch/x86/kernel/i8259.c). That affects `init_ISA_irqs' only (the other > place, `make_8259A_irq', has a reference to `i8259A_chip' hardcoded). > > In this case the output would change from "dummy-dummy" to "dummy", > which IMHO has just as much value as the change from "XT-PIC-XT-PIC" to > "XT-PIC". However I don't think you'd be able to request such IRQs so > they will never show up in /proc/interrupts, making this observation > largely irrelevant. If you think I may be wrong here, then can you > please find such a system and try this change with it (or can someone > else reading this make this check for me by any chance)? Unfortunately > all x86 hardware I have does have an 8259A pair. > > Also please note that both places explicitly refer to the name of the > IRQ chip being installed as the name of the handler as well, with > `i8259A_chip.name' and `chip->name' respectively, this is hardcoded. > So no matter which chip is used there'll be a duplicate name in > /proc/interrupts. > > Does this answer address your concern? Yeah, it addresses it, I'll queue up your fix, thanks! Ingo