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From: Paul Brook <paul@codesourcery.com>
Subject: Re: [Qemu-devel] [5849] Change MMIO callbacks to use offsets,
	not  absolute addresses.
Date: Thu, 26 Feb 2009 15:19:42 +0000
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To: qemu-devel@nongnu.org
Cc: Blue Swirl <blauwirbel@gmail.com>

> >  You either have to explicitly sync state (In teh case of SPARC this
> > means saving PC and NPC), or you have to know about the fault in the
> > low-level TLB processing code where you still have enough information to
> > recover this information. Once you get into an IO handler you've no way
> > of figuring out what the current CPU state is. The "not in all
> > cases"/"some faults" you mention above is relatively rare instructions
> > that may fault v.s. every memory access.
>
> Well, until r4431 we always saved PC and NPC for all memory access
> instructions, but with that commit, some of the checks could be
> removed and everything still work.

I don't believe that everything still works.  Alignemnt checks work because 
they are enfored by the low-level TLB code. I'm pretty sure unassigned access 
faults are broken.

Paul