On 18.03.15 20:18, Andrew Jones wrote: > On Wed, Mar 18, 2015 at 03:08:20PM -0400, Andrew Jones wrote: >> In reply to this message I'll send two series' one for KVM and >> one for QEMU. The two series' are their respective component >> complements, and attempt to implement cache coherency for arm >> guests using emulated devices, where the emulator (qemu) uses >> cached memory for the device memory, but the guest uses >> uncached - as device memory is generally used. Right now I've >> just focused on VGA vram. >> >> This approach is the "MADV_UNCACHED" type that Paolo suggested. >> This type of approach could also be described as "make userspace's >> memory access type match the expected access type of the guest", >> and Mario has suggested using a memory driver, which could have >> the same result. >> >> The coming series' is inspired by both Paolo's and Mario's >> suggestions, but it uses a kvm memslot flag, rather than an >> madvise flag, and thus for the memory driver, it's just KVM. >> >> See the thread >> >> https://lists.gnu.org/archive/html/qemu-devel/2015-03/msg01254.html >> >> for some more background. >> >> Thanks in advance for comments. >> >> drew > > I forgot to mention that I've done some light testing with this. > It seems to work, and without (to eye) noticeable performance > degradation.
Just for the record, I couldn't get it to work :). But I'm looking forward to the next version with MMU notifiers! Alex
