Re: [patch] PIII/Katmai & FXSAVE support, disable serial-#, 2.2.2

David Woodhouse (David.Woodhouse@mvhi.com)
Thu, 04 Mar 1999 10:57:02 +0000

jj@sunsite.mff.cuni.cz said:
> And guess what it gives you? 4 bytes from IDPROM, which you can
> change in PROM mode and you read it by means of the OS, so the OS can
> tell you any value it wants to. That's completely different to
> instruction telling CPU serial id.

OK, so we can do the same. The kernel can read the serial number(s) when it
boots, then disable it.

We can then make it available as a sysctl, and preferably changeable...

# echo "0xdeadbeefdeadbeef 0xdeadbeefdeadbeef" > /proc/sys/kernel/cpuid

The system admin can then remove world-readable permission from the file in
/proc if he so desires, and it should be possible to log each time a process
reads it.

We can also implement gethostid(), which can return the serial number of the
boot processor.

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David Woodhouse David.Woodhouse@mvhi.com Office: (+44) 1223 810302
Project Leader, Process Information Systems Mobile: (+44) 976 658355
Axiom (Cambridge) Ltd., Swaffham Bulbeck, Cambridge, CB5 0NA, UK.
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