When using the "clocksource=" flag, "Override clocksource <snip> is not HRT compatible" is seen and the clocksource is not used

Issue

• As shown below, I have set the clocksource to be tsc via the clocksource=tsc boot parameter. However, the current clocksource is xen not tsc . dmesg indicates that I need to disable tickless kernel and high resolution timer. Why do we have to disable high resolution timer?

# cat /proc/cmdline 
<snip> clocksource=tsc

# cat /sys/devices/system/clocksource/clocksource0/current_clocksource
xen