[Top] [All Lists]

Re: way selection bit for multi-way cache

To: Ralf Baechle <>
Subject: Re: way selection bit for multi-way cache
From: "Mike Uhler" <>
Date: Thu, 10 Apr 2003 12:37:47 -0700
Cc: Mike Uhler <>, Jun Sun <>,
In-reply-to: Your message of "Thu, 10 Apr 2003 21:24:30 +0200." <>
Original-recipient: rfc822;
> On Thu, Apr 10, 2003 at 11:50:53AM -0700, Mike Uhler wrote:
> > I can't comment on anything but MIPS32 and MIPS64 CPUs, but the
> > MIPS32 and MIPS64 standard is to use the bits above the index field
> > to specify the way.  See the figure entitled "Usage of Address Fields
> > to Select Index and Way" in the CACHE instruction description of the
> > MIPS32 and MIPS64 Architecture for Programmer's manuals.
> The question came up between Jun and me when revising the way of handling
> multi-way caches.  There is the MIPS32 / MIPS64 way of selecting the
> cache way - but that scheme was originally already introduced by the
> R4600.  The second somewhat less common scheme is using the lowest bits
> of the address.  That was originally introduced with the R10000 but a
> few other processors such as the R5432 and the TX49 series are using it
> as well.  Unfortunately there has been way to much creativity (usually
> a positive property but ...) among designers so this posting is an
> attempt to achieve completeness.
>   Ralf

Exactly why we made it a standard in MIPS32 and MIPS64.

  Michael Uhler, VP, Systems, Architecture, and Software Products 
  MIPS Technologies, Inc.   Email:   Pager:
  1225 Charleston Road      Voice:  (650)567-5025   FAX:   (650)567-5225
  Mountain View, CA 94043   Mobile: (650)868-6870   Admin: (650)567-5085

<Prev in Thread] Current Thread [Next in Thread>