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    SubjectRe: [Xen-devel] [PATCH 3/7] xen/hvm: Xen PV extension of HVM initialization
    On Tue, 2 Mar 2010, Jeremy Fitzhardinge wrote:
    > On 03/02/2010 01:22 AM, Ian Campbell wrote:
    > > On Tue, 2010-03-02 at 01:38 +0000, Sheng Yang wrote:
    > >
    > >> A annoy thing in pv drivers is that it would test if the domain type
    > >> is _NOT_ XEN_NATIVE. So set the domain to XEN_HVM_DOMAIN would result
    > >> in PV driver initialization then probably panic.
    > >>
    > > What _actually_ panics?
    > >
    > > Registration of the frontend devices should be completely harmless
    > > (apart from a little wasted RAM) unless a xenbus driver manages to come
    > > up and enumerate the xen bus and cause the ->probe function run.
    > >
    > > You should be gating the xenbus startup on the availability of PV
    > > functionality not the individual driver registrations. This keeps the
    > > test in a single easy to maintain place.
    > >
    > > Compare with pci_register_driver and all of the callers of that function
    > > -- not a single one of them has an "is_pci_available" test anywhere.
    > >
    > The problem is that it currently assumes xenbus is initialized by the
    > time the PV drivers init, because in a PV boot xenbus gets initted very
    > early. We need to change it so that it can cope with drivers being
    > initialized and registering with xenbus before it has been initialized.
    > We have the same problem with plain PV-on-HVM drivers as xenbus only
    > comes up as a result of probing the Xen PCI platform device, which may
    > be after the PV drivers' init functions have been called.

    Give a look at the fourth patch of the series I just posted: it
    introduces a simple driver for the Xen PCI platform device to initialize
    xenbus and gran table later on when running in a HVM domain, at the same
    time leaving the PV case as it is.

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      Last update: 2010-03-03 12:35    [W:0.021 / U:70.300 seconds]
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