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Date: Mon, 25 Nov 2013 21:26:18 +0700
From: Alexey Dokuchaev <danfe@nsu.ru>
To: Nathan Whitehorn <nwhitehorn@freebsd.org>
Subject: Re: mfpvr instruction: how to get processor version info from
 userland?
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On Mon, Nov 25, 2013 at 08:07:24AM -0600, Nathan Whitehorn wrote:
> >it seems that mfpvr should do the job, but it can only be called from
> >kernel.  Linux emulates it so user-space can have access to the info; but
> >in FreeBSD, its prototype is hidden under #ifdef _KERNEL :(
> >
> >i haven't yet made my way through this code, but have a quick question: is
> >there a way to obtain mfpvr() value from userland (thru kernel catching
> >the trap that the processor raises when a non-privileged program tries to
> >execute it), or i have to write my own kld for that?  i also wonder why it
> >was made privileged in the first place...  thanks,
> 
> You can use it fine from userland -- just copy the mfpvr() definition
> our of the header file. The architecture makes it privileged for various
> reasons (VM mobility for instance), but we emulate it.

OK, i see.  Would it more sense to open it to userland (in header file)
in this case?  Or there are reasons it's hidden behind #ifdef _KERNEL?

./danfe