On 21/04/2015 13:56, Jan Kiszka wrote: > > Basically it's an optimization. The guest can set the UC memory type on > > PCI BARs that are actually backed by RAM in QEMU, and then accesses to > > these BARs will be unnecessarily slow. It would be particularly bad if, > > for example, access to ivshmem were slowed down because the guest PAT > > says the memory is uncacheable. > > ivshmem is pv anyway - why shouldn't the guest driver take this room for > optimization into account and ask for a cached mapping? > > Is that that only use case? I guess a frame buffer would be affected as well, though probably the guest would set it to WC so it's less bad. Paolo -- 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
