linux-kernel - Re: Query about set_pages

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Message-ID: <47AF314C.9090104@lwfinger.net>
Date:	Sun, 10 Feb 2008 10:15:56 -0700
From:	Larry Finger <larry.finger@...inger.net>
To:	Arjan van de Ven <arjan@...radead.org>
CC:	LKML <linux-kernel@...r.kernel.org>
Subject: Re: Query about set_pages_* API

Arjan van de Ven wrote:
> On Sat, 09 Feb 2008 15:40:12 -0700
> Larry Finger <Larry.Finger@...inger.net> wrote:
> 
>> Is the set_pages_* API that replaces change_page_attr described
>> somewhere? I have been unable to find it with Google.
>>
>> I'm trying to modify the VirtualBox kernel module to work with
>> 2.6.24-git (and 2.6.25) on x86_64 architecture. The current code has
>> a value of the third argument of the call (prot) with 3 variants. All
>> variations have the following bits set: _PAGE_PRESENT, _PAGE_RW,
>> _PAGE_DIRTY, and _PAGE_ACCESSED. Number 2 adds _PAGE_NX to the above,
>> and number 3 adds _PAGE_GLOBAL to the bits in variation 1.
>>
>>  From the code in arch/x86/mm/pageattr.c, I figured I need to call
>> set_pages_wb() unconditionally, and set_pages_nx() if _PAGE_NX is
>> set. Will these calls be sufficient? I thought about calling
>> set_pages_rw(), but that entry is not exported.
>>
> 
> ok looking at the actual code.. it seems to only care about making a piece of memory executable 
> (and then clearing it before freeing), so all you need is set_memory_x() and set_memory_nx()

Thanks for the response. It is working now.

Larry
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