Re: disabling Intel PSN

Marc Mutz (Marc@Mutz.com)
Mon, 20 Dec 1999 18:49:36 +0100

"Dwayne C . Litzenberger" wrote:
>
<snip>
> I suggest the default be that the PSN be simply disabled at startup. A
> kernel parameter (optionally compiled into the kernel) could change this
> so that the PSN is read before it is disabled. The PSN could then be
> stored in a /proc variable (and also read through a (perhaps privileged)
> sysctl command). This variable could be modified (ala /proc/sys/*) if the
> user wishes (whether or not they actually have a PIII). The PSN would
> then become no more infringent on privacy than a variable MAC adddress.
>
<snip>

This is a very good suggestion, IMO. When the kernel reads the PSN's[1]
at boot time disables them in the processors, publishes them via e.g.
/proc/cpuinfo and makes them alterable by echo psn <your number here> >
/proc/cpuinfo (or the like), everyone can be made happy:

1.) The ones that find it a useful feature can stay with the real psn,
2.) The ones that are paranoid (like me), can add said echo command to
their startup-scripts
3.) The ones that find it useful for distinguishing their hardware, but
do not want to let the outside world know the real value, can read the
true value, change it to a self-defined one (line 1, 2, 3, ...) and
continue with those.

Additionally, you _have_ to export the psn via /proc or the like,
because if you let an application execute the CPUID command (I think
that was what reveals the PSN?) on SMP, that value can change between
calls. I think I never heard of that complication in this thread.

Marc

-- 
Marc Mutz <Marc@Mutz.com>        http://marc.mutz.com/Encryption-HOWTO/
University of Bielefeld, Dep. of Mathematics / Dep. of Physics


PGP-keyID's:   0xd46ce9ab (RSA), 0x7ae55b9e (DSS/DH)




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