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.
I have a small Shuttle Barbebone computer which I’m mainly using as a KVM hypervisor on top of Ubuntu Server 14.04 to run a few VMs. Since the Barebone also sports a HDMI port and the CPU comes with an integrated Intel HD GPU I thought it would be a great Kodi (ex XBMC) mediacenter as well. However, I’ve been unable to find a working walk-through on how to install it on Ubuntu Server. Most likely because nobody ever does this on a server OS. Anyway, here’s how to install the latest Kodi release on Ubuntu Server 14.04 including hardware acceleration for the Intel HD GPU. Continue reading “How to install Kodi on Ubuntu Server 14.04”
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 “QEMU on Haswell causes spurious MCE events”
This is a heads up for everybody with an Nvidia GTX 760 (other Nvidia cards may be affected as well) trying to install OS X Yosemite 10.10 using Clover on a Hackintosh. If you’re getting a blank/black screen at the start of the installation, try to add the boot flag nv_disable=1. My screen was getting dark just after the installer displayed DSMOS has arrived when using the -v verbose boot flag. It always happened right after the installer was switching from text mode to graphics mode.
<key>Boot</key>
<dict>
<key>Arguments</key>
<string>dart=0 -v kext-dev-mode=1 nv_disable=1</string>
...(more)
Once OS X Yosemite has been installed, the nv_disable boot flag is no longer required and should be removed.
I’m running some sort of an experimental KVM guest with IPv6 connectivity only. Since it still had Ubuntu Server 13.10 installed I tried to run a do-release-upgrade on it to upgrade it to the latest Ubuntu Server release – which at the time of this writing is 14.10. However, the do-release-upgrade command kept saying that no new release could be found:
root@ipv6lab:~# do-release-upgrade Checking for a new Ubuntu release No new release found
I verified the /etc/update-manager/release-upgrades configuration file but it already contained the Prompt=normal line. After doing some digging I found out that the do-release-upgrade tries to connect to http://changelogs.ubuntu.com but there is no AAAA DNS record for this host. Essentially, this means that an Ubuntu server can’t be upgraded to a newer release over IPv6 because it can’t connect to the update info site over IPv6.
root@ipv6lab:~# dig +short changelogs.ubuntu.com A 91.189.95.36 root@ipv6lab:~# dig +short changelogs.ubuntu.com AAAA root@ipv6lab:~#
Interestingly, the Ubuntu APT repository update site is accessible over IPv6, which is why something like apt-get update runs fine on IPv6-only Ubuntu servers.
I solved the problem by creating an IPv6 to IPv4 HTTP proxy using HAProxy on a IPv4/IPv6 dual stack server. The proxy listens on an IPv6 address and “tunnels” all requests to changelogs.ubuntu.com using the IPv4 address of the changelogs server. I was able to upgrade to a newer Ubuntu release this way on an IPv6-only Ubuntu server. Continue reading “Ubuntu release upgrade says ‘no new release found’ on IPv6-only server”