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From: Paul Brook <paul@codesourcery.com>
Subject: Re: [Qemu-devel] Add ARM920T to ARM emulation
Date: Fri, 29 May 2009 23:05:28 +0100
References: <1243603405-12989-1-git-send-email-vince@simtec.co.uk>
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To: qemu-devel@nongnu.org
Cc: Vincent Sanders <vince@simtec.co.uk>

> There was some discussion of the differences between v4 and v5 with
> respect to LDR behaviour manipulating the program counter when the
> bottom bit of an adress is set. The ARM-ARM clearly defines such
> behaviour as "unpredicatble" (section A2.4.3 page 48) where it says
> "In all variants of ARMv4 and ARMv5, bits[1:0] of a value written to
> R15 in ARM state must be 0b00. If they are not, the results are
> UNPREDICTABLE." .

This statement is only applies to instructions that do not have explicit 
semantics for r15. Use of r15 as a destination in load/pop instructions is 
well defined.

Paul