Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756400AbYGKXPx (ORCPT ); Fri, 11 Jul 2008 19:15:53 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1753357AbYGKXPp (ORCPT ); Fri, 11 Jul 2008 19:15:45 -0400 Received: from mga01.intel.com ([192.55.52.88]:52197 "EHLO mga01.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753243AbYGKXPo (ORCPT ); Fri, 11 Jul 2008 19:15:44 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.30,348,1212390000"; d="scan'208";a="592073147" Date: Fri, 11 Jul 2008 16:15:43 -0700 From: Suresh Siddha To: "Eric W. Biederman" Cc: "Siddha, Suresh B" , Matthew Wilcox , "linux-pci@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "grundler@parisc-linux.org" , "mingo@elte.hu" , "tglx@linutronix.de" , "jgarzik@pobox.com" , "linux-ide@vger.kernel.org" , "benh@kernel.crashing.org" , "jbarnes@virtuousgeek.org" , "rdunlap@xenotime.net" , "mtk.manpages@gmail.com" Subject: Re: Multiple MSI, take 3 Message-ID: <20080711231543.GY1678@linux-os.sc.intel.com> References: <20080711005719.GO14894@parisc-linux.org> <20080711215943.GW1678@linux-os.sc.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.4.1i Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1707 Lines: 40 On Fri, Jul 11, 2008 at 03:59:59PM -0700, Eric W. Biederman wrote: > Suresh Siddha writes: > > > With interrupt-remapping, we can program the individual interrupt > > remapping table entries to point to different cpu's etc. All we have > > to take care is, do the IRTE allocation in a consecutive block and > > program the starting index to the MSI registers. > > > > Just curious Eric, why do you think that won't work? > > Working mask/unmask. With MSI-X as specced if I mask an irq and then unmask > it, an msi message will fire if something happened while the irq was masked > and not taken care of before the irq was unmasked. That is the correct > behavior for an irq and a mmu won't let me get that. And why do we need to mask/unmask the device in the interrupt-remapping case? > > The best I can do with an iommu is to run delayed disable and set the > interrupt remapping slot in the iommu to reject the traffic. Which > is almost but not quite what I want. > > Overall introducing a new concept into the linux irq model seems a lot > cleaner and more portable, and even there we are likely to be a lot > more fragile because of the difficulty in obtaining contiguous > vectors. > > Speaking of. How many interrupt targets does the dmar iommu have > for interrupts? 16K? There can be multiple interrupt-remapping units in the platform and each of table in the remapping unit has max 64K entries. thanks, suresh -- 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/