On Thursday 13 November 2008 02:46:31 Hollis Blanchard wrote: > On Wed, 2008-11-12 at 22:51 +1030, Rusty Russell wrote: > > On Tuesday 11 November 2008 10:07:09 Hollis Blanchard wrote: > > > Both sides of the virtio interface must agree about how big a pfn > > > really is. This is particularly an issue on architectures where the > > > page size is configurable (e.g. PowerPC, IA64) -- the interface must be > > > independent of PAGE_SHIFT. > > > > > > Currently there are three distinct problems: > > > * The shift count used when passing the physical address of the ring to > > > a PCI-based back end. > > > * The ring layout itself is padded to span at least two "pages". > > > * The balloon driver operates in units of "pages". > > > > Hi Hollis, > > > > The more I thought about this, the more I think we're not solving this > > as neatly as we could. The trigger was noting that we're breaking the > > userspace API (vring_size and vring_init are exposed to userspace): I > > know that qemu cut & pastes, but that's no excuse. > > > > So instead, I've introduced separate constants for each use. Yes, > > all these constants are 12/4096. But just to be contrary, at the end > > is a patch to change lguest to 128. And there's no reason this > > couldn't change in future using some guest detection scheme. > > OK. I thought it was simpler to just say "4KB everywhere" in all aspects > of the virtio interface, but I'm happy as long as we solve the problem > somehow. :)
It is simpler, yes, but we can take this opportunity to deconflate them and make things clearer and better than the current code, not just "fix" it. Note that I still don't have a balloon patch: want to send me one? Thanks, Rusty. -- To unsubscribe from this list: send the line "unsubscribe kvm" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
