From mboxrd@z Thu Jan 1 00:00:00 1970 From: Joerg Roedel Subject: Re: IRQ remapping problem on Macbook Air 5,1 Date: Tue, 7 Aug 2012 22:10:30 +0200 Message-ID: <20120807201030.GJ1917@8bytes.org> References: <20120807194837.GB23829@thinkpad-t410> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <20120807194837.GB23829@thinkpad-t410> Sender: linux-kernel-owner@vger.kernel.org To: Seth Forshee , linux-kernel@vger.kernel.org, linux-acpi@vger.kernel.org, x86@kernel.org, Thomas Gleixner , Ingo Molnar , "H. Peter Anvin" , Len Brown , Joerg Roedel , Suresh Siddha , Yinghai Lu List-Id: linux-acpi@vger.kernel.org Hi Seth, On Tue, Aug 07, 2012 at 02:48:37PM -0500, Seth Forshee wrote: > This machine has a bug in its ACPI tables that's causing it to fail to > boot unless intremap=off is passed to the kernel. The MADT defines a > single IOAPIC with id 2, but the remapping unit defined in DMAR matches > id 0. Thus interrupt remapping fails, and the kernel panics with the > message "timer doesn't work through Interrupt-remapped IO-APIC." If I > force the use of the non-matching ir hardware for the IOAPIC everything > seems to works fine. dmesg for the working boot is below. There are AMD systems with similar problems. For example I had a system with 2 IO-APICs but only one was described in the IOMMU ACPI table. > I'm looking at how to make this machine able to boot by default. OS X > obviously boots, and Windows presumably boots as well since Apple > officially supports running Windows on its hardware. These operating systems probably don't support interrupt remapping, or the IOMMU at all. > I've got a patch to leave IRQ remapping disabled whenever any IOAPIC > does not have a matching ir hardware unit. This gets it to boot, but I > thought I'd check and see whether anyone had any better ideas for how to > fix this. This is exactly how I fixed this issue on the AMD side too. Mind to submit the patch? Thanks, Joerg