[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 2/3] libxl: add domain config parameter to force start of qemu
On 18/03/16 08:11, Juergen Gross wrote: > On 17/03/16 17:06, George Dunlap wrote: >> On Thu, Mar 10, 2016 at 3:00 PM, Juergen Gross <jgross@xxxxxxxx> wrote: >>> Today the device model (qemu) is started for a pv domain only in case >>> a device requiring qemu is specified in the domain configuration >>> (qdisk, vfb, channel). If there is no such device the device model >>> isn't started and hence it is possible to add such a device to the >>> domain later. >>> >>> Add a domain configuration parameter to specify the device model is >>> to be started in any case. This will enable adding devices with a >>> qemu based backend later. >>> >>> While the optimal solution would be to start the device model >>> automatically when needed this would require some major rework of >>> libxl at multiple places. >>> >>> Signed-off-by: Juergen Gross <jgross@xxxxxxxx> >> >> So wait -- what happens now if you try to attach a disk with a qdisk >> backend to a PV guest that didn't start with qemu running? > > It won't work (that was my test case for the patch). > >> I'd really like to see patch 3 get in, but I'm not really in favor of >> this sort of a user-visible hack, particularly as we have to support >> it in libxl more or less indefinitely. > > Hmm, really? We can add a smarter variant later which will start the > device model in case it isn't started yet. Then the new config parameter > could be just ignored. Sure; but it will (probably) only actually be useful for one release cycle (now 6 months), and then it will sit around cluttering up the interface for years to come. The situation wrt hotplug has been this way for years now, and nobody has complained; I don't think an extra 6 months will be a big deal. Ultimately it's the tools maintainers' call; I wouldn't argue against it if one of them think it's a good idea. > I didn't do the smart variant as I'm not sure I could set it up in time > for 4.7. I'd be happy to do it with some assistance regarding the async > framework of libxl I'm not at all familiar with. I'm sure help could be arranged; but it might be difficult to do by 4.7. -George _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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