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Re: [PATCH v2] Revert "MIPS: make CAC_ADDR and UNCAC_ADDR account for PH

To: Leonid Yegoshin <Leonid.Yegoshin@imgtec.com>
Subject: Re: [PATCH v2] Revert "MIPS: make CAC_ADDR and UNCAC_ADDR account for PHYS_OFFSET"
From: Ralf Baechle <ralf@linux-mips.org>
Date: Wed, 26 Jun 2013 18:23:02 +0200
Cc: "Steven J. Hill" <Steven.Hill@imgtec.com>, "linux-mips@linux-mips.org" <linux-mips@linux-mips.org>, Florian Fainelli <florian@openwrt.org>
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On Wed, Jun 26, 2013 at 03:43:35PM +0000, Leonid Yegoshin wrote:

> This is a precursor for EVA specs implementation on Aptiv cores.
> 
> EVA has different virtual address sets for kernel and user space and it can 
> use memory on different physical address location. For exam, on Malta it can 
> use a natural 0x80000000, one our customer put memory into 0x40000000 etc.

Hmm...  Any significant reduction below 2GB sounds like opening a can of
worms with address space layout assumption in some application code.

I guess they were desperately looking to increase kernel memory, highmem
didn't fit the bill nor going 64 bit so this was the solution?

  Ralf

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