On Mon, 2012-07-23 at 09:56 +1000, Paul Mackerras wrote:

quoted

That indicate we should not mask the top 16 bits. So remove the

same.

Older versions of the architecture (2.02 and earler) require the
masking, so we can't just unconditionally remove it, since that would
potentially break POWER5 and PPC970.  People are definitely still
running Linux bare-metal on PPC970s (though arguably not on POWER5). 

Are you sure ? I couldn't convince myself ... the old architectures say
that it only uses some of the bits but it doesn't mark the other ones as
"reserved" (as in must be 0).

(At least 1.x, I haven't looked at 2.x with x < 03)

Cheers,
Ben.