Dear colleagues,

just to inform you about a problem I have/had:

Xen host: SL5 kernel-xen-2.6.18-419.el5.x86_64 ,xen-3.0.3-148.el5_11.x86_64, libvirt-0.8.2-29.el5_9.1.x86_64
Xen guest: SL6 kernel 2.6.32-696.16.1.el6.x86_64, kernel-firmware-2.6.32-696.18.7.el6

Guest runs fine. yum update -> kernel-2.6.32-696.18.7.el6.x86_64
Guest does not boot. Using the graphical virt-manager display you don't see anything. Only machine crashed.

Workaround:
Add
 extra = "(hd0)/boot/grub/menu.lst"
to /etc/xen/guest

xm create -c guest

Select older kernel, boot, yum remove kernel-2.6.32-696.18.7.el6.x86_64

Perhaps a problem with Spectre/Meltdown handling?

-- 

 Andreas Manschke
 Universitaet Bremen