On Fri, May 22, 2020 at 6:15 AM Pratik Vyas <m...@pd.io> wrote: > Hi Sivaram and Renato, > > I have been looking at this issue this week with Dave. (funnily Dave > and I independently also decided to write a linux patch to attach > pvclock and debugging these crashes).
My hacky "vmm-clock" implementation is here if you'd like to compare notes: https://git.sr.ht/~voutilad/linux/log/linux-5.4-obsd My goal is to strip down the implementation to the bare minimum needed for an OpenBSD guest similar to what I did with my vmmci(4) implementation: https://github.com/voutilad/virtio_vmmci One thing I've found is (at least with busybox's top(1)), the accounting for cpu utilization is wrong if you just wire up the kvm-clock clocksource. > > If you have your linux vm with kvm-clock around, can you try this rather > crude patch and see if it still crashes? This might also fix the '100% > cpu when using alpine via console' problem. >From my quick testing, with both the standard Linux 5.4 kernel with Alpine 3.11 and my 5.4.40 fork, it resolves the CPU utilization issue from the serial console, but doesn't resolve the serial console lockup when spamming the return key. I haven't dug into why yet. > For ref, this is my linux side patch to attach kvm-clock http://ix.io/2lzK > > @@ -96,7 +103,7 @@ ns8250_init(int fd, uint32_t vmid) > */ > com1_dev.pause_ct = (com1_dev.baudrate / 8) / 1000 * 10; > > - event_set(&com1_dev.event, com1_dev.fd, EV_READ | EV_PERSIST, > + event_set(&com1_dev.event, com1_dev.fd, EV_READ, > com_rcv_event, (void *)(intptr_t)vmid); pd@ I think you're missing the analogous code in ns8250_restore(). -- Dave Voutila
