From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753083Ab0FGVFn (ORCPT ); Mon, 7 Jun 2010 17:05:43 -0400 Received: from terminus.zytor.com ([198.137.202.10]:52368 "EHLO mail.zytor.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752550Ab0FGVFm (ORCPT ); Mon, 7 Jun 2010 17:05:42 -0400 Message-ID: <4C0D5F0D.7050706@zytor.com> Date: Mon, 07 Jun 2010 14:05:17 -0700 From: "H. Peter Anvin" User-Agent: Mozilla/5.0 (X11; U; Linux x86_64; en-US; rv:1.9.1.9) Gecko/20100430 Fedora/3.0.4-3.fc13 Thunderbird/3.0.4 MIME-Version: 1.0 To: "Eric W. Biederman" CC: Yinghai , mingo@redhat.com, linux-kernel@vger.kernel.org, tglx@linutronix.de, Feng Tang , Len Brown , Jacob Pan Subject: Re: [tip:x86/irq] x86, acpi/irq: Handle isa irqs that are not identity mapped to gsi's. References: <1269936436-7039-14-git-send-email-ebiederm@xmission.com> <4BE12323.2010104@oracle.com> In-Reply-To: Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 05/05/2010 02:32 AM, Eric W. Biederman wrote: >> >> can you use legacy_irq->nr_legacy_irqs instead of NR_IRQS_LEGACY ? > > No. legacy_irq->nr_legacy_irqs is just for dealing with hardware that > does not have i8259 pics. > I don't know if it is "just" for this purpose. Quite on the contrary. In fact, the fact that NR_IRQS_LEGACY is showing up at all looks like a real problem. > Here I am reserving 16 irqs above the gsi range in case we get a > weird gsi to isa irq mapping. But that 16 is exactly because those are the (platform-specific) legacy IRQs. > Currently the sfi spec doesn't mention anything explicitly. I > took a quick read through it and sfi and I presume Moorestown > is talking about non pci irqs. So I would not be surprised > if we didn't have isa device drivers running on platforms > without i8259s. I'm confused about the above. Where do you see any mention to fixed (ISA) IRQs in SFI or Moorestown? Jacob tells me they don't exist. > Currently the code had a small bug dealing with multiple ioapics and > the spec really is incomplete about how you map irqs from pci devices > to interrupts. So it looks like SFI and Moorestown are more a lab > experiment than real hardware at the moment. So I expect when > it gets completely fleshed out we will have to jump through a > similar set of hoops as we do with acpi to ensure the first 16 > irqs are not used for anything except isa irqs. Moorestown hardware certainly exists, although not all the support is upstream yet. Either which way, anything which perpetuates NR_IRQS_LEGACY as a compile-time constant is begging for people to get things wrong, and it really needs to go away. -hpa