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Re: [PATCH] 16K page size in 32 bit kernel

To: Ralf Baechle <ralf@linux-mips.org>
Subject: Re: [PATCH] 16K page size in 32 bit kernel
From: Songmao Tian <tiansm@lemote.com>
Date: Tue, 31 Jul 2007 21:49:34 +0800
Cc: Dajie Tan <jiankemeng@gmail.com>, linux-mips <linux-mips@linux-mips.org>
In-reply-to: <20070731100027.GA3983@linux-mips.org>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <20070731130950.GA5540@sw-linux.com> <20070731100027.GA3983@linux-mips.org>
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Ralf Baechle wrote:
On Tue, Jul 31, 2007 at 05:09:51PM +0400, Dajie Tan wrote:

32-bit Kernel for loongson2e currently use 16KB page size to avoid
cache alias problem.So, the definiton of PGDIR_SHIFT muse be 12+14.

Using 22 in 16K page size do not lead to a serious problem but the number
of pages allocated for page table is more than previous. (cat
/proc/vmstat | grep nr_page_table_pages)

It's been tested on FuLong mini PC(loongson2e inside).

Looking good, applied.  Thanks!

Did by coincidence any of you try 64K pages with a 32-bit kernel?

  Ralf



I think the following is more complete?

#ifdef CONFIG_64BIT_PHYS_ADDR
-#define PGDIR_SHIFT    21
+#define PGDIR_SHIFT    (PAGE_SHIFT + (PAGE_SHIFT + PTE_ORDER - 3))
#else
-#define PGDIR_SHIFT    22
+#define PGDIR_SHIFT    (PAGE_SHIFT + (PAGE_SHIFT + PTE_ORDER - 2))
#endif

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