Avi Kivity wrote: > On 02/10/2010 06:47 PM, Alexander Graf wrote: > >>>> Because on PPC, you usually run PPC32 userspace code on a PPC64 kernel. >>>> Unlike with x86, there's no real benefit in using 64 bit userspace. >>>> >>>> >>>> >>>> >>> btw, does 32-bit ppc qemu support large memory guests? It doesn't on >>> x86, and I don't remember any hacks to support large memory guests >>> elsewhere. >>> >>> >>> >> It doesn't :-). In fact, the guest we virtualize wouldn't work with > 2 >> GB anyways, because that needs an iommu implementation. >> >> > > Oh, so you may want to revisit the "there's no real benefit in using 64 > bit userspace". > Well, for normal users they don't. SLES11 is 64-bit only, so we're good on that. But openSUSE uses 32-bit userland. > Seriously, that looks like a big deficiency. What would it take to > implement an iommu? > > I imagine Anthony's latest patches are a first step in that journey. > All reads/writes from PCI devices would need to go through a wrapper. Maybe we could also define a per-device offset for memory accesses. That way the overhead might be less. Yes, Anthony's patches look like they are a really big step in that direction. Alex -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
