[Qemu-devel] Run Real Time Guest OS?

[Steve Ellenoff]

Is it possible to run a real time OS under qemu? What changes would need to 
be made?
Can it even be done?

The guest OS I'm trying to run sets the RTC System Timer 0 to a 0.25ms 
interval (~4000Hz)!! The program I'm trying to run on it, expects this time 
to be accurate, and as such, visually the program seems to be 4-5x too slow 
in qemu, which makes sense given that it's delivering only a 1024Hz timer 
irq.

I've noticed in the source code that qemu sets this max value of 1024Hz 
(1ms) for the timer, which from what I understand is a limit of the Linux 
kernel itself, ie, that's the most the kernel can support.

If I was to run qemu in an RT version of linux ( I was considering KURT ), 
or using some other patch to allow for finer granularity of the linux 
timers, what else would need changing in qemu, ie, what timings are expected 
& assumed by qemu currently?

Before I waste any time investing KURT or other avenues more closely, I just 
wanted to get an idea from you guys if this would even be possible. To me it 
seems like it should be pretty easy to do, but then again, I'm still getting 
familiar with qemu's internals.

Thanks for any advice-
Steve