On 14 May 2015 at 14:03, Andrew Jones <drjones@xxxxxxxxxx> wrote: > On Thu, May 14, 2015 at 11:37:46AM +0100, Peter Maydell wrote: >> On 14 May 2015 at 11:31, Andrew Jones <drjones@xxxxxxxxxx> wrote: >> > Forgot to (4): switch from setting userspace's mapping to >> > device memory to normal, non-cacheable. Using device memory >> > caused a problem that Alex Graf found, and Peter Maydell suggested >> > using normal, non-cacheable instead. >> >> Did you check that non-cacheable is definitely the correct >> kind of Normal memory attribute we want? (ie not write-through). > > I was concerned that write-through wouldn't be sufficient. If the > guest writes to its non-cached memory, and QEMU needs to see what > it wrote, then won't write-through fail to work? Unless we some > how invalidate the cache first? Well, I meant more that the correct mapping for userspace is the same as the guest, whatever that is, and so somebody needs to look at what the guest actually does rather than merely hoping NormalNC is OK. (For instance, do we need to provide support for QEMU to map both NC and writethrough?) -- PMM _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
