Bug#887676: Stretch kernel 4.9.0-5-amd64 breaks Xen PVH support
Package: linux-image-amd64
Version: 4.9+80+deb9u
Not sure if this needs to go to the Debian Kernel team or Debian Xen
team, so please feel free to reclassify as necessary. I'm leaning
toward this being a kernel bug, as the Xen packages had not changed
when this issue was introduced; only the kernel changed.
Description:
============
Latest Stretch kernel (4.9.0-5-amd64), released per DSA-4082-1, breaks
Xen PVH domU support. Booting the domU with pvh = '1' set in its config
file gets the boot process as far as pyGRUB, but once the kernel itself
begins to boot, the domU immediately crashes. Even with 'quiet' removed
from the kernel's boot options, the kernel outputs nothing before it
dies.
Thinking this was possibly the work of the Meltdown mitigation, I added
`pti=off` to the domU's kernel boot options. No effect.
Steps to reproduce:
===================
1. Run Xen PV domU in PVH mode (PVH = '1' in domU config file),
2. Upgrade domU's kernel from 4.9.0-4-amd64 to 4.9.0-5-amd64,
3. Reboot domU using latest kernel.
Workaround:
===========
I could find no workaround with this kernel. I either had to disable
Xen PVH mode (set PVH = '0') for the domU or roll back to using kernel
4.9.0-4-amd64.
Setup:
======
- Dom0 kernel: 4.9.0-5-amd64
- DomU kernel: 4.9.0-5-amd64
- Xen hypervisor version: xen-hypervisor-4.8-amd64 (4.8.2+xsa245-
0+deb9u1)
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