Saving to 32 bits of GPRs in signal context

[Benjamin Herrenschmidt]

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.

Ben.