On Sun, 2007-09-30 at 19:03 +0200, Avi Kivity wrote: > rusty@xxxxxxxxxxxxxxx wrote: > > > These helper routines supply most of the virtqueue_ops for hypervisors > > which want to use a ring for virtio. Unlike the previous lguest > > implementation: > > > > 1) The rings are variable sized (2^n-1 elements). > > 2) They have an unfortunate limit of 65535 bytes per sg element. > > 3) The page numbers are always 64 bit (PAE anyone?) > > 4) They no longer place used[] on a separate page, just a separate > > cacheline. > > 5) We do a modulo on a variable. We could be tricky if we cared. > > 6) Interrupts and notifies are suppressed using flags within the rings. > > > > Users need only get the ring pages and provide a notify hook (KVM > > wants the guest to allocate the rings, lguest does it sanely). > > This fixes an ABI. I don't think we have enough experience with this to > set an ABI for 2.6.24. I also owe you a patch for scatter/gather > indirection instead of chaining. > > It is okay to put this in as long as 2.6.24 drivers won't try to talk to > 2.6.25+ hosts (which presumably will have a stable ABI). We could do > this by having "stable API" feature bit which the new drivers will > require, and an "2.6.24 ABI" feature bit which the current drivers will > require, but the whole config interface itself is too new for this in my > opinion. Yes, but this is what lguest is for, to play without fixing an ABI. I fully expect incompatible tweaks before KVM causes the ABI to nail down. And it's going to be far easier to manage lguest-kvm cooperation with this in tree than outside. Cheers, Rusty. _______________________________________________ Virtualization mailing list Virtualization@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linux-foundation.org/mailman/listinfo/virtualization
