Mar 212010
Magic SysRqs
One of the most powerful ways to debug or recover Linux is through the Magic SysRq keys.
Normally, if you’re using a serial console, you send BREAK, followed by the command you want. However, this doesn’t work with the Xen paravirtualized serial console driver. Instead, you have to use Ctrl+o, followed by the command you want.
For instance, to do an emergency sync, press Ctrl+o, then s.
Note that you use Ctrl+o instead of BREAK for both dom0 and domU serial consoles – they both are using the Xen paravirtualized driver.