On Fri, Jul 28, 2017 at 08:20:57AM +0200, Thomas Huth wrote: > On 28.07.2017 06:02, David Gibson wrote: > > On Tue, Jul 25, 2017 at 08:03:06PM +0200, Greg Kurz wrote: > >> The "phandle" property of the XICS node is referenced by the > >> "interrupt-map" > >> property of each PHB node. This is used by the guest OS to setup IRQs for > >> all PCI devices. > >> > >> QEMU uses an arbitrary value (0x1111) for this phandle, but SLOF converts > >> this value to a SLOF specific one, which is then presented to the guest OS. > >> > >> This patches introduces the new KVMPPC_H_UPDATE_PHANDLE hcall, which is > >> used > >> by SLOF to communicate the patched phandle value back to QEMU. This value > >> is then cached and preserved accross migration until machine reset. > >> > >> This is required to be able to support PHB hotplug. > >> > >> Note, that SLOF already has some code to call KVMPPC_H_RTAS_UPDATE, so we > >> have to introduce its number even if QEMU currently doesn't implement it. > >> > >> Suggested-by: Thomas Huth <th...@redhat.com> > >> Signed-off-by: Greg Kurz <gr...@kaod.org> > > > > Ugh. I really, really hope we can avoid this, though I don't > > immediately see how. Having to have two way communication between > > qemu and SLOF about the device tree contents just seems like opening > > the door to endless complexities. > > > > This is basically a consequence of the fact that both qemu and partly > > responsible for constructing the device tree for the guest, and that's > > not easy to avoid. > > > > Hrm.. Thomas, I know it's not really the OF way, but would it be > > feasible to change SLOF to use the phandles as supplied by qemu rather > > than creating its own? > > I don't see a way to do this in an easy, clean, reasonable way. SLOF > uses pointers to internal structures as phandles all over the place. You > likely can't replace that so easily without rewriting half of the whole > device tree related code in SLOF, I guess...
Dang, that's what I suspected.
Just to be clear the phandles are used directly as raw pointers?
There's not even some lookup macro we could change?
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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