Saving to 32 bits of GPRs in signal context

[Kumar Gala]

On May 29, 2007, at 6:46 PM, Olof Johansson wrote:

> On Wed, May 30, 2007 at 07:32:33AM +1000, Benjamin Herrenschmidt  
> wrote:
>> On Tue, 2007-05-29 at 08:10 -0500, Kumar Gala wrote:
>>> This is all problematic since some 64-bit implementations may not
>>> guarantee the upper bits are valid when in 32-bit mode.  Look at the
>>> 'Computation Modes' section in the architecture specs 2.03 or
>>> greater
>>> for embedded processors.
>>
>> Yuck. Well, we might need to export a spearate CPU feature bit to
>> indicate that it's the case then.
>
> No need for a new bit, you should be able to key off of PPC_FEATURE_64
> && !PPC_FEATURE_BOOKE.

Nope, the architecture allows embedded to behave like server parts  
and support the full 64-bit registers.  We really should have a new  
feature bit so that if someone has an implementation of an embedded  
part that supports the functionality, they get the benefit.

- k