From mboxrd@z Thu Jan 1 00:00:00 1970 From: George Dunlap Subject: Re: RFC: Automatically making a PCI device assignable in the config file Date: Wed, 10 Jul 2013 15:45:49 +0100 Message-ID: <51DD739D.9090206@eu.citrix.com> References: <51D6CC76.4040906@citrix.com> <51D6CDE2.90808@eu.citrix.com> <20957.26581.15772.550615@mariner.uk.xensource.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii"; Format="flowed" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20957.26581.15772.550615@mariner.uk.xensource.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: Ian Jackson Cc: Andrew Cooper , Ian Campbell , "xen-devel@lists.xen.org" List-Id: xen-devel@lists.xenproject.org On 10/07/13 14:55, Ian Jackson wrote: > George Dunlap writes ("Re: [Xen-devel] RFC: Automatically making a PCI device assignable in the config file"): >> Auto-seizing is fairly dangerous; you could easily accidentally yank out >> the ethernet card, or even the disk that dom0 is using. I really think >> it should have to be enabled on a device-by-device basis. > I don't think this makes any sense. > > In practice you are saying that in order to avoid mistakes, the local > admin must provide the BDF of the device to be passed through in two > separate places. That's not what I had in mind; what I had in mind was something like this: pci = [ '08:04.1,seize=1' ] Or alternately: xl pci-attach h0 08:04.1,seize=1 One could also imagine having something in xl.conf like the following: pci.autoseize = [ '08:04.1','01:00.0' ] In this case you wouldn't be simply copy and pasting, because you'd probably have different domains handling each device. But in any case, this was just exploring the alternatives -- I don't think that's the best thing to do. > But that doesn't actually help. If this is all properly documented > and so forth (ie, if the admin has a smooth experience and doesn't > trip over having dailed to "seize" the device), they will just > cut-and-paste the same value into both places in the config. > > They will also mutter under their breath to ask why this is > necessary... If someone can accidentally type "xl pci-attach 08:04.0" instead of "xl pci-attach 08.04.1" and suddenly completely lose their network connectivity (or yank their hard drive out), then I think they'll appreciate it. In any case, at the moment it's much worse: you have to either scriptwise run "xl pci-assignable-add" a device, or add an exclusion on the Linux commandline in grub. So far I'm the only person I know who has complained about it. :-) -George