Re: Problem with random.c and PPC

From: Oliver Xymoron (
Date: Fri Aug 16 2002 - 12:15:09 EST

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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