Subject: Linux on LSI EZ4102

From: Ralph Metzler <[email-masked]>
Date: Fri, 13 Apr 2001 02:08:45 +0200 (CEST)

Hi,

does anybody have experience with the LSI EZ41XX line of MIPS cores
and Linux, especially regarding the cache handling?
They have a R3000-like MMU architecture and most of the MIPS2 command
set but a totally different cache.
Without cache enabled the Linux port I did works fine but with cache
the ethernet driver and the MMU behave badly. I thought I implemented
the flushing routines correctly but it seems I missed something.
If somebody already did work on this architecture please let me know.

Thanks,

Ralph

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From: Quinn Jensen <[email-masked]>
Date: Wed, 18 Apr 2001 10:24:02 -0600

Are the caches two-way (or more)?  If so, check
to see if the way select bit(s) are contiguous
with the offset for indexed cache operations.
If there is a hole, you have to flush in two
parts, or flush as if the cache was big enough
to span the hole.

Quinn

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From: Ralph Metzler <[email-masked]>
Date: Wed, 18 Apr 2001 21:02:16 +0200 (CEST)

> parts, or flush as if the cache was big enough

The i-cache is two-way and the d-cache one-way.
Since I followed the LSI sample code quite closely when implementing
the flush calls I don't think that this is the problem.
(Although I found one bad bug in the LSI code, so maybe ...) 

I first based my port on the Linux version from linux-vr.sourceforge.net
which is a modified 2.4.0test9. Now it seems others have problems with
caching on that kernel with other MIPS architectures too. 
So, I'll better move to one of the 2.4.3-ac kernels first. I saw that
they contain quite a few changes, especially in the cache handling. 

Cheers,
Ralph

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From: Keith M Wesolowski <[email-masked]>
Date: Wed, 18 Apr 2001 13:23:24 -0700

> they contain quite a few changes, especially in the cache handling. 

Any -ac kernel contains at most the same changes that are in the oss
tree.  Trees other than the oss one, including ac, are likely to
contain more bugs.

-- 
Keith M Wesolowski <[email-masked]> http://foobazco.org/~wesolows
------(( Project Foobazco Coordinator and Network Administrator ))------
	"Nothing motivates a man more than to see his boss put
	 in an honest day's work." -- The fortune file

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From: Alan Cox <[email-masked]>
Date: Wed, 18 Apr 2001 22:11:42 +0100 (BST)

> tree.  Trees other than the oss one, including ac, are likely to

-ac has all the stuff Ralf has sent me. Linus has most of that. In some
ways -ac has less bugs (eg the oss tree has serious disk corruption bugs -ac
doesnt) but I certainly cant guarantee -ac will always build on mips, and 
right now with the sem changes it quite probably wont.

Alan

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From: Ralf Baechle <[email-masked]>
Date: Fri, 20 Apr 2001 10:45:52 -0300

> right now with the sem changes it quite probably wont.

It won't nor will Linus latest pre-patch.

Time to start sending more patches to you & Linus ...

  Ralf