Description of problem:
Red Hat has ported some of the hyperthreading support from the 2.5 to the 2.4
kernels. In particular, code which prints "Physical processor ID" and "Number of
siblings" in /proc/cpuinfo has been added as linux-2.4.18-cpuinfo-siblings.patch
as of kernel-2.4.18-18.7.x

However, although this is #ifdef'd for SMP kernels, if you look at the 2.5
series (arch/i386/kernel/cpu/proc.c) you will see that it also has to be wrapped
in an if (cpu_has_ht) test.

Otherwise, running on a non-hyperthreaded-cpu SMP system, the physical id and
number of siblings will print out uninitialized values, possibly different each
time.

Version-Release number of selected component (if applicable):
kernel-2.4.18-18.7.x and newer

How reproducible:
Easily

Steps to Reproduce:
1. On an SMP system without hyperthreaded cpus:
   while /bin/true ; do egrep 'Physical|sibling' /proc/cpuinfo ; done
    
Actual results:
Physical processor ID   : 591210800
Number of siblings      : 1
Physical processor ID   : 741353507
Number of siblings      : 1
etc...

Expected results:
Nothing at all - this should not be displayed for non-hyperthreaded cpu's.

Additional info: