From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mark McLoughlin Subject: Re: Freeze with KVM_CLOCK, undocumented dependency VIRTIO_BLK -> VIRTIO_PCI Date: Wed, 02 Jul 2008 11:11:04 +0100 Message-ID: <1214993464.13909.7.camel@muff> References: <485DBBCD.5060600@codemonkey.ws> Reply-To: Mark McLoughlin Mime-Version: 1.0 Content-Type: text/plain Content-Transfer-Encoding: 7bit Cc: Bernhard Schmidt , kvm@vger.kernel.org To: Anthony Liguori Return-path: Received: from mx1.redhat.com ([66.187.233.31]:55859 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755181AbYGBKLg (ORCPT ); Wed, 2 Jul 2008 06:11:36 -0400 In-Reply-To: <485DBBCD.5060600@codemonkey.ws> Sender: kvm-owner@vger.kernel.org List-ID: On Sat, 2008-06-21 at 21:41 -0500, Anthony Liguori wrote: > Bernhard Schmidt wrote: > > b) apparently VIRTIO_BLK works only when VIRTIO_PCI and thus PCI is > > enabled in the kernel. Otherwise the vda* device is not visible and the > > guest does not find its root filesystem. > > > > Is this expected? If yes, is it possible to add the appropriate > > dependency in the kernel configuration or amend the description > > accordingly? > > > > VIRTIO_BLK doesn't depend on VIRTIO_PCI. VIRTIO_PCI allows you use to > virtio devices under KVM. > > This is all documented FWIW in the Kconfig and in a number of places on > the wiki. I wonder would it be useful to default to building in (i.e. not as a module) virtio_pci if building with e.g. KVM_GUEST? There's two issues here: 1) It's easy to forget about virtio_pci - if we used KVM_GUEST as a general "this kernel may be run on KVM" config, then it would be a good hint that virtio_pci should be built 2) Although we currently build virtio_pci as a module in Fedora, it leads to a pretty strange situation where e.g. mkinitrd and anaconda need to explicitly include the virtio_pci module; I don't think there's analogous situation where bus probing logic is in a module rather than built into the kernel Cheers, Mark.