Bug #400

Intel CPUID2 (data in ecx after cpuid) patch

Added by TGEN almost 9 years ago. Updated over 8 years ago.

Status:ClosedStart date:
Priority:LowDue date:
Assignee:-% Done:


Target version:-


Attached patch adds detection, storage and printing of additional flags
reported by cpuid in the ecx register on newer Intel CPUs. One problem I
have, is that cpu_feature (and the new cpu_feature2) are declared in
sys/systm.h, when they're actually machine dependent. Shouldn't they
rather be in e.g. machine/cpufunc.h?

The printing stuff was obtained from FreeBSD, as for the CPUID2 constants.

Thomas E. Spanjaard

intel_cpuid2.diff Magnifier (4.39 KB) TGEN, 12/07/2006 02:42 PM


#1 Updated by qhwt+dfly almost 9 years ago

You can rip this `#ifndef CPUID2_EST' part completely, because CPU
feature bits won't change after the machine booted. The code was
only there because I didn't want to mess with identcpu.c :)

#2 Updated by TGEN almost 9 years ago

Will do. What do you think about the <sys/systm.h> containing MD

Thomas E. Spanjaard

#3 Updated by qhwt+dfly almost 9 years ago

It's been moved from <machine/md_var.h> by this commit:

The current users of cpu_feature outside /sys/{cpu,machine} are:
the last two files use it to deal with TSC register, which is also
specific to CPU. I guess that this is the reason cpu_feature has been
moved into <sys/systm.h> (but you should ask Matt, of course).

It looks OK to me to move it into cpufunc.h; my only question is
what the name(s) of CPU name is for vkernel, if we're to move to


#4 Updated by TGEN almost 9 years ago

Hmm. Imho, it should remain under machine/, perhaps with an include in

You mean MI code has special handling of the x86 TSC? There ought to be
a better way...

I'm not yet positive of where it really should end up, none of the
cpu*.h files, nor specialreg.h seem entirely appropriate. But I'll
commit the original patch with the removing of the logic in est.c in 24
hours, leaving this for another time.

Thomas E. Spanjaard

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