On Tue, Jul 10, Konrad Rzeszutek Wilk wrote: > On Tue, Jul 10, 2012 at 02:50:03PM +0200, Olaf Hering wrote: > > Add xs_reset_watches function to shutdown watches from old kernel after > > kexec boot. The old kernel does not unregister all watches in the > > shutdown path. They are still active, the double registration can not > > be detected by the new kernel. When the watches fire, unexpected events > > will arrive and the xenwatch thread will crash (jumps to NULL). An > > orderly reboot of a hvm guest will destroy the entire guest with all its > > resources (including the watches) before it is rebuilt from scratch, so > > the missing unregister is not an issue in that case. > > > > With this change the xenstored is instructed to wipe all active watches > > for the guest. However, a patch for xenstored is required so that it > > accepts the XS_RESET_WATCHES request from a client (see changeset > > 23839:42a45baf037d in xen-unstable.hg). Without the patch for xenstored > > the registration of watches will fail and some features of a PVonHVM > > guest are not available. The guest is still able to boot, but repeated > > kexec boots will fail. > > OK, so this should make the reset of xenstore work with the new hypervisor, > but with older ones (like Amazon), it won't and we won't have regressions, > right?
The reset happens only if "platform-feature-xs_reset_watches" exists, so old hosts are supposed to be ok. Olaf -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
