Linux on LSI EZ4102

Linux on LSI EZ4102

[Ralph Metzler]

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

Re: Linux on LSI EZ4102

[Quinn Jensen]

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

owner-linux-mips@oss.sgi.com wrote:

> 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

Re: Linux on LSI EZ4102

[Ralph Metzler]

Quinn Jensen writes:
 > 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.

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

Re: Linux on LSI EZ4102

[Keith M Wesolowski]

On Wed, Apr 18, 2001 at 09:02:16PM +0200, Ralph Metzler wrote:

> 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. 

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 <wesolows@foobazco.org> 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

Re: Linux on LSI EZ4102

[Alan Cox]

> 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.

-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

Re: Linux on LSI EZ4102

[Alan Cox]

> 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.

-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

Re: Linux on LSI EZ4102

[Ralf Baechle]

On Wed, Apr 18, 2001 at 10:11:42PM +0100, Alan Cox wrote:

> > 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.
> 
> -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.

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

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

  Ralf

Re: Linux on LSI EZ4102

[Ralf Baechle]

On Wed, Apr 18, 2001 at 10:11:42PM +0100, Alan Cox wrote:

> > 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.
> 
> -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.

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

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

  Ralf