Re: [PATCH v10] irq: add quirk for broken interrupt remapping on 55XX chipsets

[Joerg Roedel <joro@8bytes.org>]

On Tue, Apr 16, 2013 at 04:38:32PM -0400, Neil Horman wrote:
> A few years back intel published a spec update:
> http://www.intel.com/content/dam/doc/specification-update/5520-and-5500-chipset-ioh-specification-update.pdf
> 
> For the 5520 and 5500 chipsets which contained an errata (specificially errata
> 53), which noted that these chipsets can't properly do interrupt remapping, and
> as a result the recommend that interrupt remapping be disabled in bios.  While
> many vendors have a bios update to do exactly that, not all do, and of course
> not all users update their bios to a level that corrects the problem.  As a
> result, occasionally interrupts can arrive at a cpu even after affinity for that
> interrupt has be moved, leading to lost or spurrious interrupts (usually
> characterized by the message:
> kernel: do_IRQ: 7.71 No irq handler for vector (irq -1)
> 
> There have been several incidents recently of people seeing this error, and
> investigation has shown that they have system for which their BIOS level is such
> that this feature was not properly turned off.  As such, it would be good to
> give them a reminder that their systems are vulnurable to this problem.  For
> details of those that reported the problem, please see:
> https://bugzilla.redhat.com/show_bug.cgi?id=887006
> 
> Signed-off-by: Neil Horman <nhorman@tuxdriver.com>
> CC: Prarit Bhargava <prarit@redhat.com>
> CC: Don Zickus <dzickus@redhat.com>
> CC: Don Dutile <ddutile@redhat.com>
> CC: Bjorn Helgaas <bhelgaas@google.com>
> CC: Asit Mallick <asit.k.mallick@intel.com>
> CC: David Woodhouse <dwmw2@infradead.org>
> CC: linux-pci@vger.kernel.org
> CC: Joerg Roedel <joro@8bytes.org>
> CC: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
> CC: Arkadiusz Miśkiewicz <arekm@maven.pl>

Applied with some small changes to my x86/vt-d branch, thanks Neil.