[PATCH] ppc: Add support for bigger page sizes than 4KB on PPC44x

[Wolfgang Denk]

Dear Ben,

in message <1173769934.24454.67.camel at localhost.localdomain> you wrote:
>
>  - It's arch/ppc. We shouldn't do new major features on this codebase.
> You are welcome however in helping moving over 4xx to arch/powerpc :-)

Will do that as soon as we have an arch/powerpc port for the 440SP /
440SPe

>  - You only adapted head_4xx.S but the config option is global to all of
> arch/ppc, thus changing it will probably break everything else. Make

You are probably right. We will try to clean this up.

>  - Have you tried other page sizes ? How hard would it be to support 16K
> and what kind of performance numbers do you get with 16K ? It's a better

16 kB should work, but was not tested so far. From our RAID oriented
calculations it's not interesting.

We tried 256 kB, but kernel linking fails with a "Not enough room for
program headers" error message. We will investigate this ASAP, but at
the moment we have other priorities. [Any hints what might  go  wrong
are welcome.]

> compromise for some applications as 64K causes significant bloat of the
> page cache (among other things).

Agreed, but this obviously depends  on  the  sort  of  application(s)
you're running.

Best regards,

Wolfgang Denk

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