Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1760066AbZANWsh (ORCPT ); Wed, 14 Jan 2009 17:48:37 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1755916AbZANWsN (ORCPT ); Wed, 14 Jan 2009 17:48:13 -0500 Received: from out01.mta.xmission.com ([166.70.13.231]:43925 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755349AbZANWsJ (ORCPT ); Wed, 14 Jan 2009 17:48:09 -0500 From: ebiederm@xmission.com (Eric W. Biederman) To: Jon Masters Cc: Ingo Molnar , Bjorn Helgaas , Stefan Assmann , Len Brown , Jesse Barnes , Olaf Dabrunz , Thomas Gleixner , Steven Rostedt , Linux Kernel Mailing List , linux-acpi@vger.kernel.org, Sven Dietrich , "Maciej W. Rozycki" References: <496B24E5.1070804@suse.de> <200901121151.53195.bjorn.helgaas@hp.com> <1231806563.4094.25.camel@perihelion.bos.jonmasters.org> <20090113014723.GA11366@elte.hu> <1231820798.4094.34.camel@perihelion.bos.jonmasters.org> <20090114114006.GF8625@elte.hu> <1231960709.23174.0.camel@londonpacket.bos.redhat.com> Date: Wed, 14 Jan 2009 14:42:47 -0800 In-Reply-To: <1231960709.23174.0.camel@londonpacket.bos.redhat.com> (Jon Masters's message of "Wed, 14 Jan 2009 14:18:29 -0500") Message-ID: User-Agent: Gnus/5.110006 (No Gnus v0.6) Emacs/21.4 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii X-XM-SPF: eid=;;;mid=;;;hst=mx04.mta.xmission.com;;;ip=24.130.11.59;;;frm=ebiederm@xmission.com;;;spf=neutral X-SA-Exim-Connect-IP: 24.130.11.59 X-SA-Exim-Rcpt-To: too long (recipient list exceeded maximum allowed size of 128 bytes) X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-DCC: XMission; sa02 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Jon Masters X-Spam-Relay-Country: X-Spam-Report: * -1.8 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.0 T_TM2_M_HEADER_IN_MSG BODY: T_TM2_M_HEADER_IN_MSG * -2.6 BAYES_00 BODY: Bayesian spam probability is 0 to 1% * [score: 0.0001] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa02 1397; Body=1 Fuz1=1 Fuz2=1] * 0.4 FVGT_m_MULTI_ODD Contains multiple odd letter combinations * 0.0 XM_SPF_Neutral SPF-Neutral Subject: Re: PCI, ACPI, IRQ, IOAPIC: reroute PCI interrupt to legacy boot interrupt equivalent X-SA-Exim-Version: 4.2.1 (built Thu, 07 Dec 2006 04:40:56 +0000) X-SA-Exim-Scanned: Yes (on mx04.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1468 Lines: 37 Jon Masters writes: > On Wed, 2009-01-14 at 12:40 +0100, Ingo Molnar wrote: > >> it's not just -rt, but it is also needed for the concept of threaded IRQ >> handlers - which was discussed at the Kernel Summit to be desired for >> mainline. > > Right. I'm poking at Thomas' patches and hope to post something soon on > that front - I'm acutely aware that this will be impacted aswell but > because it's vaguely RT related had banded it under that banner. Stepping back a moment. The only way I can see this working reliably is if we disable the boot interrupt. Anything that leaves the boot interrupt enabled means that when we disable the primary interrupt the boot interrupt will scream, and thus we must disable it as well. Which leads to my problem with the entire development process of this feature. People want the feature. People don't want to pay attention to the limits of the hardware. Which leads to countless broken patches proposed. Which leads me to conclude. - IRQ handling in the RT kernel is hopelessly broken. - IRQ threads are a bad idea. Because it is all leading to stupid patches and stupid development. None of this works reliably on level triggered ioapic irqs. Eric -- 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/