====== Send Magic SysRq to a KVM guest using virsh ======

===== Использование =====

<code>
virsh send-key guest1 KEY_LEFTALT KEY_SYSRQ KEY_H
</code>

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===== Magic SysRq =====

^  Action  ^  QWERTY  ^
| Set the console log level, which controls the types of kernel messages that are output to the console | **0** through **9** |
| Immediately reboot the system, without unmounting or syncing filesystems | **b** |
| Perform a system crash. A crashdump will be taken if it is configured. | **c** |
| Display all currently held Locks (CONFIG_LOCKDEP kernel option is required) | **d** |
| Send the SIGTERM signal to all processes except init (PID 1) | **e** |
| Call oom_kill, which kills a process to alleviate an OOM condition | **f** |
| %%When using Kernel Mode Setting, provides emergency support for switching back to the kernel's framebuffer console[4] If the in-kernel debugger 'kdb' is present, enter the debugger.%% | **g** |
| Output a terse help document to the console \\ Any key which is not bound to a command should also perform this action | **h** |
| Send the SIGKILL signal to all processes except init | **i** |
| Forcibly "Just thaw it" – filesystems frozen by the FIFREEZE ioctl. | **j** |
| Kill all processes on the current virtual console (can kill X and svgalib programs, see below) \\ This was originally designed to imitate a secure attention key | **k** |
| Shows a stack backtrace for all active CPUs. | **l** |
| Output current memory information to the console | **m** |
| Reset the nice level of all high-priority and real-time tasks | **n** |
| Shut off the system | **o** |
| Output the current registers and flags to the console | **p** |
| Display all active high-resolution timers and clock sources. | **q** |
| Switch the keyboard from raw mode, the mode used by programs such as X11 and svgalib, to XLATE mode | **r** |
| Sync all mounted filesystems | **s** |
| Output a list of current tasks and their information to the console | **t** |
| Remount all mounted filesystems in read-only mode | **u** |
| Forcefully restores framebuffer console, except for ARM processors, where this key causes ETM buffer dump | **v** |
| Display list of blocked (D state) tasks | **w** |
| Used by xmon interface on PPC/PowerPC platforms. | **x** |
| Show global CPU registers (SPARC-64 specific) | **y** |
| Dump the ftrace buffer | **z** |
| Print a summary of available magic SysRq keys | **space** |

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===== Источники =====

  * https://en.wikipedia.org/wiki/Magic_SysRq_key
  * http://dustymabe.com/2012/04/21/send-magic-sysrq-to-a-kvm-guest-using-virsh/