On 10/2/19 3:40 AM, Jan Beulich wrote: > On 01.10.2019 17:16, Boris Ostrovsky wrote: >> Currently execution of panic() continues until Xen's panic notifier >> (xen_panic_event()) is called at which point we make a hypercall that >> never returns. >> >> This means that any notifier that is supposed to be called later as >> well as significant part of panic() code (such as pstore writes from >> kmsg_dump()) is never executed. > Back at the time when this was introduced into the XenoLinux tree, > I think this behavior was intentional for at least DomU-s. I wonder > whether you wouldn't want your change to further distinguish Dom0 > and DomU behavior.
Do you remember what the reason for that was? I think having ability to call kmsg_dump() on a panic is a useful thing to have for domUs as well. Besides, there may be other functionality added post-notifiers in panic() in the future. Or another notifier may be registered later with the same lowest priority. Is there a downside in allowing domUs to fall through panic() all the way to emergency_restart()? > >> There is no reason for xen_panic_event() to be this last point in >> execution since panic()'s emergency_restart() will call into >> xen_emergency_restart() from where we can perform our hypercall. > Did you consider, as an alternative, to lower the notifier's > priority? I didn't but that wouldn't help with the original problem that James reported --- we'd still not get to kmsg_dump() call. -boris _______________________________________________ Xen-devel mailing list Xen-devel@lists.xenproject.org https://lists.xenproject.org/mailman/listinfo/xen-devel
