[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Questions about hvm domU default devices with upstream qemu
Il 05/09/2013 13:23, Stefano Stabellini ha scritto: On Wed, 4 Sep 2013, Fabio Fantoni wrote:Il 04/09/2013 15:17, Stefano Stabellini ha scritto:On Wed, 4 Sep 2013, Fabio Fantoni wrote:Il 04/07/2013 15:51, Fabio Fantoni ha scritto:Last year I posted a question about default devices of upstream qemu that differ from qemu traditional, like empty floppy and cdrom in particular. About empty floppy now is disabled as workaround. About empty cdrom Stabellini tells that is useful, so I tried to use it but cd-insert was failing,and I must define other empty cdrom on xl configuration file, for example with: ',raw,hdb,ro,cdrom'. It seem that there isn't default devices usable without define them in xen, and I think that probably need to revise the definition of the devices to avoid empty and unusable ones and to do everything as best as possible (also with possibly reviewing qemu side). Another good thing is also consider pv domU case and possible future support of spice and/or other useful features. Thanks for any reply.I seen no replies about this, I think is important improve upstream qemu support and remove the traditional ASA upstream will be equivalent or superior in all features. I also think is good idea add q35 support on xen. Seem that hvm domUs have performance limits, in particular on windows domUs (also with pv drivers) caused probably by old hardware emulation by qemu and/or xen support limited on some instruction sets. I don't know how to add essential q35 support on hvmloader to do some tests and have effective data about improvements. Anyone on this?I agree that this is important and thanks for raising the issue. It would be nice if somebody stepped up to do the q35 work.Thanks for reply, can you reply also on questions about default devices with upstream qemu please?I think it might be a good idea to keep the same set of default devices between qemu-traditional and qemu-xen. We always had an empty cdrom and I don't see why we should remove it. If cd-insert doesn't work, it's a bug and should be fixed. Supporting spice in PV guests would be hard, because spice needs QXL that is a PCI device. PV guests don't have a PCI bus. Of course if somebody did the work to make QXL and spice work with PV guests I would be happy to accept it. I agree that we should keep improving upstream QEMU, however removing qemu-traditional is not going to be easy because it's needed for compatibility when a guest started with qemu-traditional is live-migrated to a new system. But we can make sure that this remains the only use case for it. Thanks for reply.About qemu default empty and unusable floppy and cdrom I have already reply at start of year that qemu traditional does not have them. The tests were with xl only if I remember good, now I checked also on old production server with xend and qemu traditional. I confirm that hvm domUs is without empty floppy and cdrom also in that case. cd-insert works (tested with xl and upstream qemu). cd-insert does not works only with qemu default empty cdrom because is undefined on xen side. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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