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Re: mmap'ed memory cacheable or uncheable

To: Teresa Tao <Teresat@tridentmicro.com>
Subject: Re: mmap'ed memory cacheable or uncheable
From: Jun Sun <jsun@mvista.com>
Date: Mon, 28 Jul 2003 14:24:01 -0700
Cc: linux-mips@linux-mips.org, jsun@mvista.com
In-reply-to: <61F6477DE6BED311B69F009027C3F58403AA396F@EXCHANGE>; from Teresat@tridentmicro.com on Fri, Jul 25, 2003 at 03:52:33PM -0700
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <61F6477DE6BED311B69F009027C3F58403AA396F@EXCHANGE>
Sender: linux-mips-bounce@linux-mips.org
User-agent: Mutt/1.2.5i
On Fri, Jul 25, 2003 at 03:52:33PM -0700, Teresa Tao wrote:
> How about if I specify the following flags in my mmap routine just like what 
> the pgprot_noncached micro did.
>       pgprot_val(vma->vm_page_prot) &= ~_CACHE_MASK;
>       pgprot_val(vma->vm_page_prot) |= _CACHE_UNCACHED;
> 
> Will this have kernel make the mmap'd memory non-cacheable? Or is there a 
> mmap non-cacheable patch?
>

I think this might work.  Did you try it?  The performance will be bad
though as mmap() is used widely by userland.

Jun

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