[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH v1 05/10] libxl: synchronise configuration when we hotplug a device
On Fri, Jul 18, 2014 at 09:49:32AM +0100, Ian Campbell wrote: > On Thu, 2014-07-17 at 15:13 +0100, Wei Liu wrote: > > On Thu, Jul 17, 2014 at 12:44:43PM +0100, Ian Campbell wrote: > > > On Wed, 2014-07-16 at 18:12 +0100, Wei Liu wrote: > > > > > > As we don't have a JSON config file for libxl toolstack domain > > > > > > (currently Dom0) we need to skip JSON manipulation for it. > > > > > > > > > > How hard would it be to create a stub/stunt JSON for dom0 when we > > > > > notice > > > > > it is missing? Or from e.g. xencommons perhaps? > > > > > > > > > > > > > We need to determine: > > > > 1. when / where to generate such thing (xencommons?) > > > > 2. what to put in it > > > > > > > > I have yet had answers for #2. The simplest version can be "{}" I think. > > > > That is an empty configuration that every fields gets the default value. > > > > But we probably need more than that. > > > > > > I think you would want at least a name and perhaps a uuid? And cinfo > > > type == PV. > > > > > > Device arrays are all empty at start of day. > > > > > > Some of the stuff about target and maxmem you could perhaps infer at > > > start of day? > > > > > > > UUID (Dom0 doesn't seem to have one), name and memory targets can all be > > pulled from xenstore when they are required. > > > > And it occurs to me as I discovered Dom0 doesn't have UUID that we need > > to special-case reading / writing of Dom0's JSON config. That's because > > all other guests' JSON config are to be named with UUID and domain id. > > How annoying. :-( > > Indeed. > > I think you could generate one on boot and set it with > XEN_DOMCTL_setdomainhandle. It might be a bug that we don't do that > today (that said I can't see any evidence that xend used to do > differently). > I think this approach is OK. > > I would like to put as few things as possible in the stub because there > > doesn't seem to be a way to conveniently generate a valid JSON config > > for Dom0. Will you be against the idea of having 'xl generate-dom0-json' > > in xl to do that? Otherwise we have to basically generate a > > semi-handcoded stub in xencommons, or even a hardcoded stub. > > I'm in favour of some sort of command to "initialise dom0". Either part > of xl or a new helper app based on libxl. > > I had a similar (unposted I think) patch to add xl launch-dom0-qemu so > that it could pick the correct arch (see below, warning: it's a bit > skanky). If I were to do it again today I'd probably make a separate > $libexec helper instead of bolting it into xl though. > > Probably it should subsume this bit of xencommons too: > > echo Setting domain 0 name and domid... > ${BINDIR}/xenstore-write "/local/domain/0/name" "Domain-0" > ${BINDIR}/xenstore-write "/local/domain/0/domid" 0 > > What do you think? > Agreed. I'm think about adding "xl initialise-dom0", which: 1. generates UUID 2. writes relevant xenstore keys 3. generates stub JSON config 4. launches QEMU I think we always needs first 3 items. But I'm not quite sure about the 4th. It's more flexible to launch a process in xencommons, isn't it? Wei. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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