On 06/05/18 13:30, Richard Biener wrote: > On Mon, Jun 4, 2018 at 8:11 PM Laszlo Ersek <ler...@redhat.com> wrote: >> >> Hi! >> >> Apologies if this isn't the right place for asking. For the problem >> statement, I'll simply steal Ard's writeup [1]: >> >>> KVM on ARM refuses to decode load/store instructions used to perform >>> I/O to emulated devices, and instead relies on the exception syndrome >>> information to describe the operand register, access size, etc. This >>> is only possible for instructions that have a single input/output >>> register (as opposed to ones that increment the offset register, or >>> load/store pair instructions, etc). Otherwise, QEMU crashes with the >>> following error >>> >>> error: kvm run failed Function not implemented >>> [...] >>> QEMU: Terminated >>> >>> and KVM produces a warning such as the following in the kernel log >>> >>> kvm [17646]: load/store instruction decoding not implemented > > This looks like a kvm/qemu issue to me. Whatever that exception syndrome > thing is, it surely has a pointer to the offending instruction it could > decode?
I believe so -- the instruction decoding is theoretically possible (to my understanding); KVM currently doesn't do it because it's super complex (again, to my understanding). Thanks Laszlo
