Most recent kernel where this bug did not occur: None known
Distribution: kernel.org kernel
Hardware Environment: i386
Software Environment: boot with clock=pit on the command line
Problem Description:

The cpu_khz global is not initialized and remains 0 if you boot with clock=pit,
even if the processor does have a TSC.  This may have bad ramifications since
the variable is used in various places scattered around the kernel, though I
didn't check them all to see if they can tolerate cpu_khz = 0.  You can observe
the problem by doing "cat /proc/cpuinfo"; the cpu MHz line says 0.000.

The fix is trivial; call init_cpu_khz() from init_pit(), just as it's called
from the timers/timer_foo.c:init_foo() for other values of foo.  Patch below.

Steps to reproduce:

Boot with clock=pit on the kernel command line.

Patch (tested briefly and seems to work fine):

--- arch/i386/kernel/timers/timer_pit.c~        2005-08-24 18:54:21.000000000 -0700
+++ arch/i386/kernel/timers/timer_pit.c 2005-11-03 18:51:17.000000000 -0800
@@ -29,6 +29,9 @@
                printk(KERN_ERR "Warning: clock= override failed. Defaulting
toPIT\n");

        count_p = LATCH;
+
+       init_cpu_khz();
+
        return 0;
 }