On Tue, 2015-12-08 at 14:21 +0000, Daniel P. Berrange wrote: > On Tue, Dec 08, 2015 at 09:14:17AM -0500, Charles (Chas) Williams wrote: > > On Tue, 2015-12-08 at 11:34 +0200, Panu Matilainen wrote: > > > Hmm, got a pointer? I dont think PCI slots change between reboots > > > without physically swapping hardware, the "ethX-problem" comes from the > > > order of device discovery being unstable across boots, which is a > > > different issue and not relevant for this case. > > > > With virtual machines the ordering of PCI devices isn't always the same. > > This is especially true with OpenStack which regenerates the > > configurations on the fly. The only thing that seems to be consistent > > is the MAC address. > > The MAC address is not guaranteed to be unique of course - you can have > multiple NICs with the same MAC provided they're connected to different > subnets.
Typically not done but yes it can happen. I was referring specifically to the OpenStack case though where it causes the most trouble for me. > For OpenStack we're working on a feature that allows the user booting > an OpenStack instance to associate an arbitrary tag with each device > they have on their VM. The info about the tags and the currently assigned > device addresses is then exposed to the guest OS via the metadata service > and/or config drive and/or firmware. There will be a utility that can read > this metadata and then register tags against the corresponding devices in > the udev database. > > The idea is that people building OpenStack compatible cloud images can > configure their image to look for the device in udev with the desired > user "tag" string. That way they don't need to care about specific > device addresses directly. More info on OpenStack plans is here: > > > http://specs.openstack.org/openstack/nova-specs/specs/mitaka/approved/virt-device-role-tagging.html That would be a huge step forward but I need this to work when someone hotplugs an interface to a running image. The config drive doesn't work here since it wouldn't have the tag information. The metadata service might work (although I think cloud-init blackholes the metadata service after boot). Exposing this via the PCI device with some ACPI mechanism would be nice. _______________________________________________ systemd-devel mailing list systemd-devel@lists.freedesktop.org http://lists.freedesktop.org/mailman/listinfo/systemd-devel
