KVM VM waits forever / stuck at kernel selection screen

If a KVM virtual machine has not been properly shutdown, it may wait forever at the boot up kernel selection screen for user input. You won’t see any output when trying to virsh console into the VM from the host. You have to fire up a remote VNC session in order to press enter.

In Ubuntu Server you can override this behaviour by adding the following line to /etc/default/grub:

GRUB_RECORDFAIL_TIMEOUT=2

Don’t forget to run update-grub afterwards.

QEMU on Haswell causes spurious MCE events

A few dozen times each day, the Xeon E3-1275 v3 CPU on my SuperMicro X10SLM-F board generates a Machine Check Event (MCE). The Linux kernel logs all MCEs in /var/log/syslog:

mce: [Hardware Error]: Machine check events logged
mce: [Hardware Error]: Machine check events logged
CMCI storm detected: switching to poll mode
CMCI storm subsided: switching to interrupt mode
mce_notify_irq: 14 callbacks suppressed
mce: [Hardware Error]: Machine check events logged
mce: CPU supports 9 MCE banks
mce: [Hardware Error]: Machine check events logged

After installing mcelog I was able to pull some more detailed information about the check events:

Hardware event. This is not a software error.
MCE 0
CPU 3 BANK 0
TIME 1415087019 Tue Nov  4 08:43:39 2014
MCG status:
MCi status:
Corrected error
Error enabled
MCA: Internal parity error
STATUS 90000040000f0005 MCGSTATUS 0
MCGCAP c09 APICID 6 SOCKETID 0
CPUID Vendor Intel Family 6 Model 60

The MCEs all look the same (affected is always BANK 0), just the CPU and the APICID may differ. I updated the BIOS, replaced the ECC RAM, replaced the mainboard but the errors kept showing up. Continue reading

LXC 1.0 Web Panel for Ubuntu 14.04

LXC is awesome! You can create and start your own virtual container with just 3 commands in Ubuntu 14.04.

apt-get install lxc debootstrap lxc-templates
lxc-create -t ubuntu -n demo
lxc-start -n demo -d

It doesn’t get any easier than this. There’s even a Boostrap-based fronted available: LXC Web Panel.

lxc-web-panel

Unfortunately, LXC Web Panel doesn’t work with LXC 1.0 which is part of Ubuntu 14.04. Fortunately though, there’s a fork available on GitHub which adds support for LXC 1.0:

https://github.com/claudyus/LXC-Web-Panel

I re-forked claudyus’ LXC Web Panel fork and added support for Ubuntu 14.04 and a few other things. My forked fork is available here: https://github.com/trick77/LXC-Web-Panel Claudyus has already updated his repository with my changes.

By the way, the original author of LXC Web Panel said he’s currently working on a Bootstrap 3 based version for LXC 1.0 which will include a RESTful API and other new features. Make sure to follow¬†this guy on GitHub: https://github.com/googley