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Re: [PATCH] Fix swap entry for MIPS32 36-bit physical address

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Subject: Re: [PATCH] Fix swap entry for MIPS32 36-bit physical address
From: Sergei Shtylyov <sshtylyov@ru.mvista.com>
Date: Sat, 08 Apr 2006 01:19:11 +0400
Cc: linux-mips@linux-mips.org, Ralf Baechle <ralf@linux-mips.org>, Pete Popov <ppopov@embeddedalley.com>, Jordan Crouse <jordan.crouse@amd.com>
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Hello.

Sergei Shtylyov wrote:

Additionally, PTEs in MIPS32R2 should have the same layout for the 36-bit physical address case as in MIPS32R1, according to the architecture manuals -- so, fix the #ifdef's.

I've decided to tead off that part (incomplete anyway) and move it to a separate patch which I'll post shortly.

I'm really not sure that we need that #if defined(CONFIG_CPU_MIPS32) -- it renders CONFIG_64BIT_PHYS_ADDR non-working on all other 32-bit CPUs for which Kconfig entry claims that this support exists:

config 64BIT_PHYS_ADDR
        bool "Support for 64-bit physical address space"
depends on (CPU_R4X00 || CPU_R5000 || CPU_RM7000 || CPU_RM9000 || CPU_R10000 || CPU_SB1 || CPU_MIPS32 || CPU_MIPS64) && 32BIT

At least RM7000 has the same PTE layout as MIPS32, I guess the others also do. I suspect that the intent was to limit this option to the Alchemy CPUs where it's *really* necessary?

WBR, Sergei

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