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Re: [PATCH] Add support for 4KS cpu.

To: "Maciej W. Rozycki" <macro@linux-mips.org>
Subject: Re: [PATCH] Add support for 4KS cpu.
From: Franck <vagabon.xyz@gmail.com>
Date: Tue, 4 Oct 2005 15:10:28 +0200
Cc: Ralf Baechle <ralf@linux-mips.org>, linux-mips@linux-mips.org
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Reply-to: Franck <vagabon.xyz@gmail.com>
Sender: linux-mips-bounce@linux-mips.org
2005/10/4, Maciej W. Rozycki <macro@linux-mips.org>:
> On Tue, 4 Oct 2005, Franck wrote:
>
> > This patch adds support for both 4ksc and 4ksd cpus. These cpu are
> > mainly used in embedded system such as smartcard or point of sell
> > devices as they provide some extra security features.
>
>  Please send patches inline.

I can see it inlined...what email viewer are you using ?

>
>  Apart from the change to "arch/mips/kernel/cpu-probe.c", which is useful,
> what's the benefit of the changes?  Specifically how is selecting e.g.
> "CPU_4KSC" meant to be different from "CPU_MIPS32_R2"?  Do you want to
> make GCC tune your code according to a specific's CPU pipeline
> description?  If so, then it should probably be done a bit differently and
> there is actually no need to differentiate between specific members of the
> 4K family.
>

True, but we may have some differences in future. For example, they
both implements smart mips instructions. See options passed to GCC in
mips Makefile, they're different from CPU_MIPS32_R2 ones. They also
have a couple of instructions very useful for cryptographic
algorithms. And have some extra bits in TLB to protect pages from
being execute for example. These are the main differences that I can
remember. Big fat warning: I sent all support I have done for these
cpu, _not_ more, _not_ less. I agree it's almost nothing but it's a
start...

> > Signed-off-by: Franck <vagabon.xyz@gmail.com>
>

Ok I'll change it.

Thanks
--
               Franck

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