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Re: [PATCH 2.6] tlbwr hazard for NEC VR4100

To: "Maciej W. Rozycki" <macro@linux-mips.org>, ica2_ts@csv.ica.uni-stuttgart.de
Subject: Re: [PATCH 2.6] tlbwr hazard for NEC VR4100
From: Yoichi Yuasa <yuasa@hh.iij4u.or.jp>
Date: Thu, 2 Dec 2004 10:56:26 +0900
Cc: yuasa@hh.iij4u.or.jp, ralf@linux-mips.org, linux-mips@linux-mips.org
In-reply-to: <Pine.LNX.4.58L.0412020019050.20966@blysk.ds.pg.gda.pl>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20041201234943.584d88e8.yuasa@hh.iij4u.or.jp> <20041202000713.GO3225@rembrandt.csv.ica.uni-stuttgart.de> <Pine.LNX.4.58L.0412020019050.20966@blysk.ds.pg.gda.pl>
Sender: linux-mips-bounce@linux-mips.org
On Thu, 2 Dec 2004 00:24:30 +0000 (GMT)
"Maciej W. Rozycki" <macro@linux-mips.org> wrote:

> On Thu, 2 Dec 2004, Thiemo Seufer wrote:
> 
> > If 64bit kernels are ever relevant for VR41xx, you might want to use
> > the same branch trick as it is used for R4[04]00. IIRC it reduced the
> > handler size from 34 to 30 instructions, saving another branch.
> 
>  Isn't that based on specific properties of the R4[04]00 pipeline?  It may
> still work for the VR41xx, but you can't take it for granted, so it should
> be double-checked.  Given the conditions it's probably worth the hassle,
> though.

The specification of VR41xx does not have the guarantee to the branch trick.
Furthermore, VR41xx has the NEC original pipeline.

I think that the present method is exact for VR41xx.

Yoichi

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