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Re: [RFC] Separate time support for using cpu timer

To: Jun Sun <>
Subject: Re: [RFC] Separate time support for using cpu timer
From: "Maciej W. Rozycki" <>
Date: Wed, 21 Apr 2004 15:19:45 +0200 (CEST)
In-reply-to: <>
Organization: Technical University of Gdansk
Original-recipient: rfc822;
References: <> <> <>
On Tue, 20 Apr 2004, Jun Sun wrote:

> >  It makes it separate again -- more maintenance burden and a bigger
> > opportunity to have functional divergence, sigh...
> Pretty much true for lots of improvement we made in the past a couple of
> years .... :)

 Hmm, s/improvement/hacks/, perhaps?

> >  Additionally I don't think using the CP0 Count & Compare registers for
> > the system timer is the way to go.  It's rather a way to escape when
> > there's no other possibility.  A lot of systems have a reliable external
> > timer interrupt source and using it actually would free the CP0 registers
> > for other uses, like profiling or a programmable interval timer.
> I was rather neutral on this point until I started to add HRT/VST support to 
> MIPS.  When adding such features you really just want one common timer code.
> And the best choice for MIPS is cpu timer.

 Well, with the _hpt_ abstraction layer you have one common timer code,
regardless of the actual timer hardware used.  If there's some
functionality you miss there, we may discuss about possible solutions.

+  Maciej W. Rozycki, Technical University of Gdansk, Poland   +
+        e-mail:, PGP key available        +

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