[LinuxBIOS] Timer frequencies

Marc Jones marc.jones at amd.com
Fri Oct 5 18:10:27 CEST 2007

Myles Watson wrote:
> I got Bochs to fail the same way the hardware (my Tyan s2892) fails when 
> I turned down the timer tick interrupt frequency.  I’m having trouble 
> finding the place where the timer gets set up.  (Grepping for 
> time,rtc,timer,hz, etc.)
> Can someone tell me where I can make the interrupts come at 100 Hz in 
> LinuxBIOS?
> Thanks,
> Myles

I believe that you are looking for calibrate_tsc() in 
cpu\x86\tsc\delay_tsc.c. That only sets up channel2. No reason you 
couldn't make changes in your mainboard but I'm not sure the setting 
will stick. I would expect the linux kernel reprogram the PIT (maybe not 
if it is using ACPI timer or HPET)?


Marc Jones
Senior Firmware Engineer
(970) 226-9684 Office
mailto:Marc.Jones at amd.com

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