On 23 March 2018 at 12:01, Auger Eric <eric.au...@redhat.com> wrote: > Hi, > > On 23/03/18 11:26, Peter Maydell wrote: >> On 23 March 2018 at 10:24, Auger Eric <eric.au...@redhat.com> wrote: >>> Hi, >>> >>> I observe a regression on KVM accelerated qemu-system-aarch64: >>> >>> Unexpected error in kvm_device_access() at >>> /home/augere/UPSTREAM/qemu/accel/kvm/kvm-all.c:2164: >>> 2018-03-23T09:59:59.629439Z qemu-system-aarch64: KVM_GET_DEVICE_ATTR >>> failed: Group 6 attr 0x000000000000c664: Device or resource busy >>> 2018-03-23 10:00:00.085+0000: shutting down, reason=crashed >> >> Can you get a backtrace for this? (I guess you'd need to fiddle >> with the kvm_device_access() code to make it assert rather >> than passing back the error). > > OK. I will try to do so. As I could have expected, I cannot reproduce on > a standalone qemu command line. The problem observed above is seen with > libvirt launch which may be doing some other QMP stuff concurrently?
Hmm, that could be a bit painful to debug. I dunno if libvirt has a "launch QEMU under gdb" option. If not, you could try something like: if (condition we want to get a backtrace on) { printf("hit condition, attach gdb to process %d\n", (int)getpid()); for (;;) { } } and then QEMU will sit in a loop waiting for you to do a gdb path/to/qemu <pid> thanks -- PMM