FW: pIII Serial (or lack there-of)

Jones D (djones2@glam.ac.uk)
Thu, 14 Oct 1999 09:49:15 +0100


> Well, I don't see how this would help; after the serial is
> disabled via MSR 0x119 magic, it can't be re-enabled until you reboot..

I say remove the code which is disabling it.
The kernel should not set the policy.
If a user wants to disable it, they should use a userspace tool
to interface the MSR. (But an MSR driver is needed first)

> Ploping the data to a file in /proc owned by root with 0400
> perms would probably be the best thing if it needs to be
> accessed (someone _has_ to have a use for it), but it has
> to be read and saved before it's disabled..

Yes, of course writing the MSRs should be a root-only thing.

> As a side note, most bioses allow it to be disabled at boot
> time (mine included), and I would rather linux left the bit
> twiddling to me.. but I guess I can just go comment out the
> relevant lines :)

My point exactly.

> Also, reading MSRs works fine (as a normal user) with the rdmsr
> instruction; I haven't tried writing them though (I would
> hope that isn't allowed in userland)

You shouldn't be able to read them either, as AFAIR, it's a ring 0
instruction. You should segfault immediately.

regards,

Dave.

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