On Wed, Sep 12, 2012 at 12:53 PM, Alexander Graf <ag...@suse.de> wrote: > On 09/12/2012 04:54 PM, Erlon Cruz wrote: >> >> Hi all, >> >> We are planning to implement DLPAR capacity on QEMU pSeries. As we > > > What is DLPAR? Hotplug support?
Yes, basically the way PowerVM uses to dynamically add memory, cpu, and I/O slots to logical partitions (LPARs) > >> lack of experience in the internals of the arch we would like you guys >> to give us some design directions >> and confirm if we going in the right direction. Our first idea is: >> >> 1 - to patch 'spapr.c' so it can dynamically insert/remove basic >> items into the device tree. > > > What exactly would you like to patch into it? We already do have support for > dynamic dt creation with the spapr target. > Actually we were not sure if the machine could do that. So we can add things to the tree after booting it? >> 2 - create a host side device that will be used with a guest side >> driver to perform guest side operations and communicate changes from >> host to the guest (like DynamicRM does in PowerVM LPARs). We are not > > > Why not just use hypercalls? The hypercalls are initiated from the guest side right? We also need a way to the host send things to guest. Using hypercall also would require a guest side KM. >> planning to use powerpc-tools and want to make resource management >> transparent (i.e. no need to run daemons or userspace programs in the >> guest, only this kernel driver). >> 3 - create bindings to support adding/removal ibmvscsi devices >> 4 - create bindings to support adding/removal ibmveth devices >> 5 - create bindings to support adding/removal PCI devices >> 6 - create bindings to support adding/removal of memory > > > This is going to be the hardest part. I don't think QEMU supports memory > hotplug yet. AFAIC ballonning is what QEMU provides so far which is fine to x86. > >> - Do we need to do this the way PowerVM does? We have tested >> virtio ballooning and it can works with a few endiannes corrections. > > > I don't know how PowerVM works. But if normal ballooning is all you need, > you should certainly just enable virtio-balloon. PowerVM works with Logical Memory Blocks (LMB). The hypervisor hotplugs memory blocks to guest's memory. Not only a 'borrowing' from the guests, right Ben? >> 7 - create bindings to support adding/removal CPUs >> - is SMP supported already? I tried to run SMP in a x86 host >> and the guest stuck when SMP is enabled > > > SMP should work just fine, yes. Where exactly does it get stuck? I think that is right after the guest kernel enables SMP [ 7.478259] Faulting instruction address: 0xc00000000053bbec [ 7.479521] Oops: Kernel access of bad area, sig: 11 [#1] [ 7.479694] SMP NR_CPUS=1024 NUMA pSeries http://pastebin.com/VMtRyaTE > > >> - would be possible to work on this without a P7 baremetal >> machine? > > > At least for device hotplug, it should be perfectly possible to use an old > G5 with PR KVM. I haven't gotten around to patch all the pieces of the > puzzle to make -M pseries work with PR KVM when it's running on top of pHyp > yet, so that won't work. > > >> We have a P7 8205-E6B, is that possible to kick PHYP out? > > > Ben? > > >> Any ideia on how much effort (time/people) the hole thing would take? >> Any consideration about this is much appreciated :) > > > Phew. It's hard to tell. Depends heavily on how good your people are :). Well, considering someone like you :p, so we would just need to multiply it by 5 :P > > > Alex > >
