Actual/operating CPU frequency (fwd)

Ronald G. Minnich rminnich at
Wed Feb 23 05:38:00 CET 2005

An interesting question. AFAIK there is no general purpose way to get this 
out of the CPU, am I wrong on this? I figure you have to at least talk to 
the chipset and get some info ...


---------- Forwarded message ----------
Date: Tue, 22 Feb 2005 16:29:40 -0700
From: Patrick McCormick <pat at>
To: Ronald G. Minnich <rminnich at>
Subject: Actual/operating CPU frequency

Hi Ron,

Would you happen to have any source around (assembly is fine) that will
return the actual clock speed that a processor (Intel and AMD) is running
at?  I have the start of some code but I'm having a tough time getting the
details worked out. I know the BIOS has a 'ticker' with a known speed so I
could then use the time step counter to eventually get to the cpu
frequency but but I haven't found out exactly how to do this in several

Any ideas?  This code will eventually have to run under both Linux and Windows



More information about the coreboot mailing list