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From: Segher Boessenkool <segher@kernel.crashing.org>
Subject: Re: [PATCH 1/3] powerpc: POWER7 optimised copy_page using VMX
Date: Fri, 17 Jun 2011 22:26:25 +0200
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: paulus@samba.org, mikey@neuling.org, linuxppc-dev@lists.ozlabs.org,
	Anton Blanchard <anton@samba.org>
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>> +	addi	r1,r1,STACKFRAMESIZE
>> +
>> +	.align	5
>
> Do we know that the blank will be filled with something harmless ?

Yes.  See ppc_handle_align() in gas/config/tc-ppc.c : it fills with nops
(ori 0,0,0), and a branch if there are more than four nops, and for 
POWER6
and POWER7 it puts a group-terminating insn (ori 1,1,0 resp. ori 2,2,0) 
at
the end.

It has done this (well, nops at least) since 2001.


Segher