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8.10.4. frequency, mode, and present

The frequency attribute is used to set a fixed frequency, and is measured in Hz. This attribute is only relevant when the name element has a value of tsc. All other timers operate at a fixed frequency (pit, rtc).
mode determines how the time source is exposed to the guest virtual machine. This attribute is only relevant for a name value of tsc. All other timers are always emulated. Command is as follows: <timer name='tsc' frequency='NNN' mode='auto|native|emulate|smpsafe'/>. Mode definitions are given in the table.

Table 8.5. mode attribute values

ValueDescription
autoNative if TSC is unstable, otherwise allow native TSC access.
nativeAlways allow native TSC access.
emulateAlways emulate TSC.
smpsafeAlways emulate TSC and interlock SMP
present is used to override the default set of timers visible to the guest virtual machine..

Table 8.6. present attribute values

ValueDescription
yesForce this timer to the visible to the guest virtual machine.
noForce this timer to not be visible to the guest virtual machine.