Re: [Libguestfs] Fedora Rawhide / libguestfs 1.23.14 now enables -cpu host, +kvmclock

Passing '-cpu host' is meant to cause qemu to pass the same CPUID flags from the host up to the appliance. The major benefit of this is that the appliance can use all CPU features available to optimize eg. checksumming, crypto, RAID XOR operations, zero fill. However in practice this can cause strange problems on some hardware: https://bugzilla.redhat.com/show_bug.cgi?id=870071 This manifests itself as particular operations failing randomly, especially if RAID or crypto is involved. If you enable debugging you would see a kernel stack trace similar to the one shown in the bug above (and possibly many other variations). If you see anything like this, please file a bug.