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From: Segher Boessenkool <segher@kernel.crashing.org>
Subject: Re: Saving to 32 bits of GPRs in signal context
Date: Tue, 29 May 2007 16:38:45 +0200
To: Kumar Gala <galak@kernel.crashing.org>
Cc: Ulrich Weigand <Ulrich.Weigand@de.ibm.com>,
	Paul Mackerras <paulus@samba.org>, Steve Munroe <sjmunroe@us.ibm.com>,
	Anton Blanchard <anton@samba.org>,
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> But we can't do that any more since the architecture specifically
> allows for the 'upper bits' not to have valid data in them.

That's not PowerPC, that's BookE ;-P  If what you're
saying is true in the 2.03 POWER ISA, even for server
class implementations, that would be very unfortunate.

Or perhaps you misread, there are a few insns that
have undefined results in the high half word.  Could
you give a reference please?

If you mean Book I 1.5.2, that is for embedded class
(i.e., BookE) CPUs only.


Segher