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Date: Mon, 17 Oct 2005 17:22:59 -0700
From: "H. Peter Anvin" <hpa@zytor.com>
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To: Jeff Garzik <jgarzik@pobox.com>
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Subject: Re: [RFC] RNG rewrite...
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Jeff Garzik wrote:
> 
>> MSR instructions cannot execute out of userspace, but the MSR driver
>> might be possible to use.  It's usually quite slow, however.
> 
> MSRs are used for setup, not for actual data.
> 
> Intel:  magic MMIO address (readb)
> AMD:    magic PIO address (inl)
> VIA:    CPU instruction ('xstore')
> 

For setup, the MSR driver is fine.

	-hpa