linux-kernel - Re: ARM cortex A9 feature

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Message-ID: <CABi1daFp=mKw0kq=Vm_T9RKeHfnXsA-kssdRm56AhkaJ4FjCxA@mail.gmail.com>
Date:	Thu, 14 Jul 2011 23:03:17 -0700
From:	Dave Hylands <dhylands@...il.com>
To:	naveen yadav <yad.naveen@...il.com>
Cc:	kernelnewbies@...linux.org, linux-kernel@...r.kernel.org,
	linux-arm-kernel@...ts.infradead.org
Subject: Re: ARM cortex A9 feature

Hi naveen,

On Thu, Jul 14, 2011 at 10:15 PM, naveen yadav <yad.naveen@...il.com> wrote:
> Hi dave,
>
> Thanks for answering, but I think question 2, answer  is still not clear to me .
>
> my question is why exclusive L2.
>
> 8.1.4 Exclusive L2 cache
> The Cortex-A9 processor can be connected to an L2 cache that supports
> an exclusive cache
> mode. This mode must be activated both in the Cortex-A9 processor and
> in the L2 cache
> controller.
> In this mode, the data cache of the Cortex-A9 processor and the L2
> cache are exclusive. At any
> time, a given address is cached in either L1 data caches or in the L2
> cache, but not in both. This
> has the effect of greatly increasing the usable space and efficiency
> of an L2 cache connected to
> the Cortex-A9 processor. When exclusive cache configuration is selected:
> • Data cache line replacement policy is modified so that the victim
> line always gets evicted
> to L2 memory, even if it is clean.
> • If a line is dirty in the L2 cache controller, a read request to this address
>
>
> what is usecase for this . This is my question .

Since I've never used one, I'm not sure. Maybe somebody else knows.

-- 
Dave Hylands
Shuswap, BC, Canada
http://www.davehylands.com
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