From mboxrd@z Thu Jan 1 00:00:00 1970 From: Avi Kivity Subject: Re: Prevent IRQ sharing for PCI passthrough Date: Fri, 14 May 2010 20:14:24 +0300 Message-ID: <4BED84F0.8050600@redhat.com> References: <4BEC3534.7060707@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Cc: kvm@vger.kernel.org, Chris Wright To: Dirk Gouders Return-path: Received: from mx1.redhat.com ([209.132.183.28]:57373 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755069Ab0ENROi (ORCPT ); Fri, 14 May 2010 13:14:38 -0400 In-Reply-To: Sender: kvm-owner@vger.kernel.org List-ID: On 05/14/2010 12:37 PM, Dirk Gouders wrote: > >>> Even after extensive searching/reading, I am not sure if it possible to >>> prevent a PCI card from sharing an interrupt with other devices or >>> probably manually assign a free interrupt to that card via some kernel >>> parameter and would be glad if someone could give me an answer to that >>> question. >>> >>> >> There is an ACPI _SRS method which can be used to move interrupts >> around. However Linux doesn't appear to expose it. Even if it did, >> the interrupt may be shared on the motherboard, in which case nothing >> would help (though you might be able to share it with unused devices). >> > You mean by providing a custom DSDT, right? > A quick look in drivers/acpi/pci_link.c shows a TBD comment mentioning > _SRS but I will have to have a deeper look at this subject, because its > quite new to me. > > No, there should be an _SRS method in your existing DSDT. But Linux doesn't call it (except after resume etc.) and doesn't allow the user to use _SRS to move interrupts around. -- Do not meddle in the internals of kernels, for they are subtle and quick to panic.