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Re: Does HIGHMEM work on 32-bit MIPS ports?

Subject: Re: Does HIGHMEM work on 32-bit MIPS ports?
From: David VomLehn <>
Date: Tue, 26 Feb 2008 13:06:53 -0800
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On Wed, 20 Feb 2008, David VomLehn wrote:

> Hmm, this is not good. I've got a MIPS 24Kc processor with a very
> awkward memory layout. Any hints?

What does it mean "very awkward"? What sort of problems do you have that you are trying to solve?

Specifically, we have two banks of memory. The first starts at 0x10000000, which is no big deal (other than wasting the page map entries for the first chunk of memory). The second starts at 0x60000000, so:

  1. We have to access it with high memory, and
  2. There is a huge section of unused page map entries.

As it turns out, it is starting to look like we're making progress with the problem with high memory: In __flush_dcache_page, nothing is done if PageHighMem() returns true. Not surprisingly, this leads to Bad Things(tm). What we are working through now is making sure that we understand exactly what *should* be happening.

David VomLehn,
The opinions expressed herein are likely mine, but might not be my employer's...

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