doc: update release notes about LAPIC timer in OVMF
@@ -46,7 +46,9 @@ What's new in v2.1
* Open Virtual Machine Firmware (OVMF) now uses a Local Advanced
Programmable Interrupt Controller (LAPIC) timer as its local time
- instead of the High Precision Event Timer (HPET).
+ instead of the High Precision Event Timer (HPET). This provides the
+ working timer service for the realtime virtual machine (RTVM) booting
+ process.
* Grub is the recommended bootloader for ACRN. For more information,
see :ref:`using_grub`.
