23.16. Timer Element Attributes
The
name element contains the name of the time source to be used. It can have any of the following values:
| Value | Description |
|---|---|
| pit | Programmable Interval Timer - a timer with periodic interrupts. When using this attribute, the tickpolicy delay becomes the default setting. |
| rtc | Real Time Clock - a continuously running timer with periodic interrupts. This attribute supports the tickpolicy catchup sub-element. |
| kvmclock | KVM clock - the recommended clock source for KVM guest virtual machines. KVM pvclock, or kvm-clock allows guest virtual machines to read the host physical machine’s wall clock time. |
The
track attribute specifies what is tracked by the timer, and is only valid for a name value of rtc.
| Value | Description |
|---|---|
| boot | Corresponds to old host physical machine option, this is an unsupported tracking option. |
| guest | RTC always tracks the guest virtual machine time. |
| wall | RTC always tracks the host time. |
The
tickpolicy attribute and the values dictate the policy that is used to pass ticks on to the guest virtual machine.
| Value | Description |
|---|---|
| delay | Continue to deliver at normal rate (ticks are delayed). |
| catchup | Deliver at a higher rate to catch up. |
| merge | Ticks merged into one single tick. |
| discard | All missed ticks are discarded. |
The
present attribute is used to override the default set of timers visible to the guest virtual machine. The present attribute can take the following values:
| Value | Description |
|---|---|
| yes | Force this timer to be visible to the guest virtual machine. |
| no | Force this timer to not be visible to the guest virtual machine. |
