[Qemu-devel] PIT clock count

[Robert Falk]

Hi,

we are developing an x86 application that we are testing using qemu and
are having some issues with the PIT clock count. We are using PIT clock
count as a reference to measure cpu frequency:

wait_wrap()
a=read_current_cycles()
wait_wrap()
b=read_current_cycles()
calculate_freq(a,b)...

The problem is that when running in qemu it sometimes "loops twice" in the
wrap wait, thus reporting twice the cycles. The same problem occurs
whether I am running 100Hz or 1000Hz.

Is this a known bug? And is there any solution? I recall I have seen
similar problems with VMWare and Linux.