.. _rtc-virt-hld:

RTC Virtualization
##################

This document describes the RTC virtualization implementation in
ACRN device model.

vRTC is a read-only RTC for For pre-launched VM, Service OS and post-launched RT VM. It supports RW for CMOS address port 0x70 and RO for CMOS data port 0x71. Reads to CMOS RAM offsets are fetched by reading CMOS h/w directly and writes to CMOS offsets are discarded.