Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758570Ab0DAT10 (ORCPT ); Thu, 1 Apr 2010 15:27:26 -0400 Received: from sj-iport-5.cisco.com ([171.68.10.87]:35971 "EHLO sj-iport-5.cisco.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751222Ab0DAT1X (ORCPT ); Thu, 1 Apr 2010 15:27:23 -0400 Authentication-Results: sj-iport-5.cisco.com; dkim=neutral (message not signed) header.i=none X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: Av0EANuQtEurR7H+/2dsb2JhbACDEpgrcZ0ciEOQTIErgmtrBIMj X-IronPort-AV: E=Sophos;i="4.51,350,1267401600"; d="scan'208";a="176102308" From: Tom Lyon To: Avi Kivity Subject: Re: [PATCH 0/1] uio_pci_generic: extensions to allow access for non-privileged processes Date: Thu, 1 Apr 2010 12:24:45 -0700 User-Agent: KMail/1.9.9 Cc: kvm@vger.kernel.org, linux-kernel@vger.kernel.org, "Hans J. Koch" , gregkh@suse.de References: <201003311708.38961.pugs@lyon-about.com> <201004010906.47321.pugs@lyon-about.com> <4BB4C591.8000102@redhat.com> In-Reply-To: <4BB4C591.8000102@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset="utf-8" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <201004011224.45336.pugs@lyon-about.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1389 Lines: 38 On Thursday 01 April 2010 09:10:57 am Avi Kivity wrote: > On 04/01/2010 07:06 PM, Tom Lyon wrote: > > On Thursday 01 April 2010 08:54:14 am Avi Kivity wrote: > >> On 04/01/2010 06:39 PM, Tom Lyon wrote: > >>>>> - support for MSI and MSI-X interrupts (the intel 82599 VFs support > >>>>> only MSI-X) > >>>> > >>>> How does a userspace program receive those interrupts? > >>> > >>> Same as other UIO drivers - by read()ing an event counter. > >> > >> IIRC the usual event counter is /dev/uioX, what's your event counter > >> now? > > > > Exact same mechanism. > > But there are multiple msi-x interrupts, how do you know which one > triggered? You don't. This would suck for KVM, I guess, but we'd need major rework of the generic UIO stuff to have a separate event channel for each MSI-X. For my purposes, collapsing all the MSI-Xs into one MSI-look-alike is fine, because I'd be using MSI anyways if I could. The weird Intel 82599 VF only supports MSI-X. So one big question is - do we expand the whole UIO framework for KVM requirements, or do we split off either KVM or non-VM into a separate driver? Hans or Greg - care to opine? -- 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/