[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Xen 4.x / Linux 3.x (dom0 and HVM domU) and NIC handling
On Fri, Dec 02, 2011 at 11:11:38AM +0100, Stefan Bader wrote: > On 01.12.2011 19:09, Pasi Kärkkäinen wrote: > > On Thu, Dec 01, 2011 at 04:09:38PM +0100, Stefan Bader wrote: > >> Moving to public discussion... > >> > >> This was found with Xen hypervisor version supporting device unplugging > >> and the > >> domU kernel having net-/blkfront and pci platform built-in (or as module). > >> > >> The block device is defined as hda and the NIC type=ioemu (so theoretically > >> guests without pv support would work, too). > >> > >> Since both drivers are present, the kernel tries to unplug the emulated > >> devices > >> and succeeds. The blkfront driver detects the xvda device available in > >> parallel > >> and is working ok. > >> > >> However the network interface does not work. There are entries present > >> under > >> sysfs for the xenbus but trying to bring it up fails with errors. And also > >> there > >> seems to be no mac address set (all zeros in sysfs). > >> When the type=ioemu is removed in the configuration, this works. > >> > >> I have not much more debugging information beyond that, yet. But it sounds > >> a bit > >> like NICs should behave the same as block devices. So if there is an > >> emulated > >> device defined there will be an alternate paravirt interface for it and > >> after > >> unplugging the emulated ones we end up with the pv ones. > >> Is that something that can be seen with newer Xen versions, too (I am > >> using 4.1.1)? > >> > > > > Hey, > > > > Have you seen?: > > http://wiki.xen.org/xenwiki/XenLinuxPVonHVMdrivers > > > > Especially the following note: > > "NOTE! If you have "type=ioemu" specified for the "vif"-line, PVHVM drivers > > WILL NOT work! Don't specify "type" parameter for the vif. (with type=ioemu > > the pvhvm nic in the VM will have mac address full of zeroes - and thus > > won't work!)." > > > > "type=ioemu" is not needed, at least with xm/xend toolstack both HVM and > > PVHVM guests work OK without it. > > > > -- Pasi > > > Thanks Pasi, > > hmm, so it is documented actually and thus sort of expected. Still it is > confusing. For one driver it does not make a difference to use the form of an > emulated device in the config, for the other it does. The xl stack works, the > xm > stack does not. > And then, ok this is probably a quite naive approach, it seemed to make sense > to > go through the pain of always having potentially both interfaces available > (emulated and pv) so in theory the same guest config can accommodate a guest > os > supporting one or the other (or easily switch from one to the other). > Otherwise > I would expect an emulated device only when I have hd? in the config and a pv > device when I write xvd?. > This works for both HVM and PVHVM (also mentioned on the wiki page): vif = [ 'mac=00:16:5e:02:07:45, bridge=xenbr0, model=e1000' ] So there's no need for "type=ioemu" option with xm/xend. You can switch between HVM and PVHVM with: xen_platform_pci=0|1 -- Pasi _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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