How do I issue a sysrq on a libvirt/kvm guest using "virsh send-key"?

Environment

• Red Hat Enterprise Linux
• libvirt/kvm

Issue

• I would like to issue a sysrq to a libvirt/kvm guest without logging in via the serial console, ssh, etc.

Resolution

Issue the following from the host:

# virsh send-key <guest_domain_name> KEY_LEFTALT KEY_SYSRQ KEY_<SYSRQ>

Where:

• <SYSRQ> is the capitalized sysrq you would like to issue
• <guest_domain_name> is the name of the guest

For example, to collect a thread dump (sysrq-t) from a guest named rhel5vm, run:

# virsh send-key rhel5vm KEY_LEFTALT KEY_SYSRQ KEY_T

For example, to crash the VM thorugh sysrq run

# virsh send-key <VM-NAME> KEY_LEFTALT KEY_SYSRQ KEY_C

Notes:

• sysrq is only effective if it has been enabled. For more information, please refer to What is the SysRq facility and how do I use it?
• If you need to collect a vmcore, it is simpler to use the virsh dump command, which requires no pre-configuration of the guest.

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