Re: [PATCH] ARM: decompressor: Fix mmu mapping for non-DRAM address space.

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On Wednesday 09 May 2012 09:18 PM, Russell King - ARM Linux wrote:
> On Wed, May 09, 2012 at 06:00:10PM +0530, Shilimkar, Santosh wrote:
>> On Wed, May 9, 2012 at 5:53 PM, Russell King - ARM Linux
>> <linux@xxxxxxxxxxxxxxxx> wrote:
>>> On Wed, May 09, 2012 at 02:20:28PM +0530, Shilimkar, Santosh wrote:
>>>> The only change done common code is  clearing 'XN' bit for DRAM
>>>> region in page table entries. The other change of setting the DACR
>>>> register is done in ARMv7 specific code.
>>> Yes, XN is an ARMv6+ thing.  Before ARMv5, it was implementation defined.
>>> Some implementations used the bit to mean "allow writes to update the
>>> cache".  Other implementations labelled this bit as "should be zero"
>>> while others labelled it as "should be one".
>> Good to know.
>>> The upshot of this is, we know that having this bit as '1' means that
>>> all the CPUs we support today work.  I would be _very_ concerned to
>>> change this bit to zero as we _really_ don't know how the pre-ARMv6
>>> CPUs would react.
>> I agree.
>>> The solution to this is pretty simple - if ARMv6+ needs a different
>>> base section mapping value, then we need to extract that from the code
>>> and pass in the base section mapping value.
>>> I'll sort out a patch later today for this.
>> Great.
> This works for my 4430SDP board.  I haven't booted it on anything else yet.
> Please can you check that this solves the issue for you?  Thanks.
Yes it does.
Are you planning to merge below patch as is or split
the patch like 1) Refactoring 2) ARMv7 fix

Either is fine with me.

Acked-by: Santosh Shilimkar <santosh.shilimkar@xxxxxx>


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