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Re: [Qemu-devel] qemu-arm: wrong execution of post-indexed loads when Rm

From: Rodrigo Vivi
Subject: Re: [Qemu-devel] qemu-arm: wrong execution of post-indexed loads when Rm and Rd are the same register
Date: Thu, 15 Mar 2007 18:19:02 -0300

On 3/15/07, Paul Brook <address@hidden> wrote:
> > This is still wrong.
> So, is this a known bug?

Still wrong implies it's a bug, and your patch does not fix it properly.

I know that...
I was not clear.. sorry...
what I mean is: do you agree that there was a bug in these instructions?

> > The writeback must happen after the load.
> We code like this because
> - we didn't find this restriction in arm reference manual

It's the Abort model section you mention below.

> - the LLVM uses this instruction expecting a result like this

The compiler knows nothing about the abort behavior. The difference is only
visible if the load faults.

> - That was the result that we got running these instructions in an OMAP1710

I suggest you check again. I'm fairly sure the arm926 implements the Base
Restored abort model.

Actually we did not test the abort model...

So, Base Restored abort model is the model that qemu implements, isn't it?
then we will try to use that and recode the patch...

thanks for your help



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