From mboxrd@z Thu Jan 1 00:00:00 1970 From: David Vrabel Subject: Re: RFC: Automatically making a PCI device assignable in the config file Date: Thu, 11 Jul 2013 12:35:42 +0100 Message-ID: <51DE988E.7020700@citrix.com> References: <20957.26468.175816.677766@mariner.uk.xensource.com> <51DD7420.5050803@eu.citrix.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <51DD7420.5050803@eu.citrix.com> List-Unsubscribe: , List-Post: List-Help: List-Subscribe: , Sender: xen-devel-bounces@lists.xen.org Errors-To: xen-devel-bounces@lists.xen.org To: George Dunlap Cc: Ian Jackson , Ian Campbell , "xen-devel@lists.xen.org" List-Id: xen-devel@lists.xenproject.org On 10/07/13 15:48, George Dunlap wrote: > On 10/07/13 14:53, Ian Jackson wrote: >> George Dunlap writes ("RFC: Automatically making a PCI device >> assignable in the config file"): >>> I've been doing some work to try to make driver domains easier to set >>> up and use. At the moment, in order to pass a device through to a >>> guest, you first need to assign it to pciback. This involves doing >>> one of three things: >>> * Running xl pci-assignable-add for the device >>> * Specifying the device to be grabbed on the dom0 Linux command-line >>> * Doing some hackery in /etc/modules.d >>> >>> None of these are very satisfying. What I think would be better is if >>> there was a way to specify in the guest config file, "If device X is >>> not assignable, try to make it assignable". That way you can have a >>> driver domain grab the appropriate device just by running "xl create >>> domnet"; and once we have the xendomains script up and running with >>> xl, you can simply configure your domnet appropriately, and then put >>> it in /etc/xen/auto, to be started automatically on boot. >>> >>> My initial idea was to add a parameter to the pci argument in the >>> config file; for example: >>> >>> pci = ['08:04.1,permissive=1,seize=1'] >>> >>> The 'seize=1' would indicate that if bdf 08:04.1 is not already >>> assignable, that xl should try to make is assignable. >> I think it's a design error that this isn't done automatically by >> default. >> >> It would be nice if there was a safety check that the device isn't >> currently in use by dom0, but I don't think it's essential. We could >> just put a note in the docs saying "if you specify your dom0 nic it >> will go away, duh" or something. > > I think it's a really bad interface decision if a simple typo might > result in you yanking out your disk. I don't think this proposal really helps with avoiding this. I think most people will end up always adding 'seize=1' because to avoid having to do so means altering config files elsewhere and rebooting. David