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Date: Fri, 16 Aug 2002 12:15:09 -0500
From: Oliver Xymoron <oxymoron@waste.org>
To: Tom Rini <trini@kernel.crashing.org>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Problem with random.c and PPC
Message-ID: <20020816171509.GJ5418@waste.org>
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On Fri, Aug 16, 2002 at 10:01:26AM -0700, Tom Rini wrote:
> On Fri, Aug 16, 2002 at 11:28:02AM -0500, Oliver Xymoron wrote:
> 
> > What PPC and other arches really need in this area is a higher
> > resolution timing source. The jiffies-based timing is rather
> > limiting, especially after the entropy accounting stops overestimating
> > things by orders of magnitude. Does the PPC port have a convenient way
> > to access the TBR or something similar?
> 
> Not knowing i386 well, what's the TBR?  But yes, on at least some of the
> cores I know there are time registers.  I'm not sure if it's an optional
> feature for PPC or not tho.

I was actually referring to the PPC's time base register, which is
about the closest equivalent to the x86's TSC. I'm pretty sure it's a
non-optional architecture feature (but I don't have my books handy),
and I believe this usually gets wired to the clock driving the memory
bus (typically 133MHz), but I've only worked with embedded PPC so I
have no idea how it's set up in commodity hardware.

-- 
 "Love the dolphins," she advised him. "Write by W.A.S.T.E.." 
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