[PATCH v2 4/6] ARM: mm: LPAE: Correct virt_to_phys patching for 64 bit physical addresses

[Santosh Shilimkar]

On Sunday 04 August 2013 01:32 AM, Nicolas Pitre wrote:
> On Sat, 3 Aug 2013, Santosh Shilimkar wrote:
> 
>> On Saturday 03 August 2013 10:01 AM, Nicolas Pitre wrote:
>>> On Sat, 3 Aug 2013, Sricharan R wrote:
>>>
>>>> On Saturday 03 August 2013 08:58 AM, Nicolas Pitre wrote:
>>>>> ... meaning that, instead of using 0x81 for the stub value on the mov 
>>>>> instruction, it only has to be 0x83.  Bits 7 and 0 still act as anchors 
>>>>> for the rotation field in the opcode, while bit 1 indicates which value 
>>>>> to patch in.
>>>>   I started with this kind of augmenting with the immediate operand
>>>>   while starting V2. But the problem was, we do the runtime patching twice.
>>>
>>> Ahhh... Bummer.
>>>
>> Sorry if it wasn't clear but I thought we discussed why patching is
>> done twice.
> 
> Yeah, I know the reasons.  I just had forgotten about the effects on the 
> anchor bits.
>
I see.
 
>> This was purely based on the discussion where RMK suggested to follow 
>> that approach to minimize code changes.
>>  
>> Looks like we need to revisit that now based on Russell's latest
>> comment.
> 
> Note that my comments on this particular patch are still valid and 
> independent from whatever approach is used globally to deal with the 
> memory alias.  I do think that the value to patch should be selected 
> depending on the opcode's rotation field which makes it compatible with 
> a double patching approach as well.
> 
Completely agree.

Regards,
Santosh