From: Keith Owens <kaos@sgi.com>
To: Bernardo Innocenti <bernie@codewiz.org>
cc: Jordan Crouse <jordan.crouse@amd.com>, kdb@oss.sgi.com,
       linux-kernel@vger.kernel.org, devel@laptop.org
Subject: Re: kdb: add rdmsr and wrmsr commands for i386 
In-reply-to: Your message of "Thu, 17 May 2007 02:36:21 -0400."
             <464BF7E5.4080105@codewiz.org> 
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Date: Thu, 17 May 2007 16:39:35 +1000
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Bernardo Innocenti (on Thu, 17 May 2007 02:36:21 -0400) wrote:
>Keith Owens wrote:
>
>> Before using MSR, you must first check that the cpu supports the
>> instruction, rd/wrmsr cause an oops on 486 or earlier.  Also using an
>> invalid msr number causes an oops, so use rd/wrmsr_safe().
>
>I didn't bother implementing those checks because kdb recovers
>nicely from GPF anyway.

Yes and no.  Yes, kdb will recover from a GPF.  No, because if the
system was already running correctly (i.e. manual entry into kdb), then
taking a GPF and not recovering will flag the rest of the system as
corrupt and can kill a running system.  I try to avoid adding spurious
system corruption.

>It's the valid MSR writes that could
>cause unrecoveable problems! :)

Tell me about it :-(

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