On 11/12/12 15:46, Christoffer Dall wrote: > On Tue, Dec 11, 2012 at 12:41 AM, Simon Baines > <simonbaines2012@xxxxxxxxxxx> wrote: >> someone can briefly explain what would be the drawback of not using the >> architected timer support when running KVM on ARM? >> Is it possible to run guests without that architected timer configuration >> enabled? > It's possible, in which case you need to use an emulated piece of > timer hardware, which will cause you a lot more vmexits to interact > with the timer to program it, for example. Is this really the case? I was under the impression that this would require qemu (or gem5 in my case) to emulate CP15 accesses to registers which aren't normally exposed to user space. I tried to boot a recent Linux kernel using KVM last week and I'm pretty sure the host kernel sent an illegal instruction trap to the guest when it tried to enable the timers using the co-processor interface. What makes matters more complicated is that the timer can't be hidden from the guest since ID_PFR1 is invariant. //Andreas _______________________________________________ kvmarm mailing list kvmarm@xxxxxxxxxxxxxxxxxxxxx https://lists.cs.columbia.edu/cucslists/listinfo/kvmarm
