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Re: [patch] rfa: fix problem with reassociating pointer additions


On Mon, Oct 04, 2004 at 10:13:15PM -0700, Eric Christopher wrote:
> 
> > > You'd think that, but the problem is in 64-bit processors with 32-bit
> > > addressing in kernel mode.
> > > 
> > > I kid you not.
> > > 
> > > MIPS64TM Architecture For Programmers Volume III, Section 4.9.
> > 
> > After much fightingwith the MIPS web site, that section is:
> > 4.9 Special Behavior for the kseg3 Segment when DebugDM = 1
> > 
> > I don't think that's what you meant.  Do you mean 4.10, which says:
> >   prohibited from generating an effective address in which there is a
> >   carry-out of bit 31. If such an address is produced,
> >   the operation of the instruction generating such an address is
> >   UNPREDICTABLE.
> > 
> 
> Right part. Must've changed between versions. It's been a while since
> I've downloaded it.
> 
> > If so, I don't see how that applies; the effective address produced
> > will be properly sign extended.
> > 
> > I would need to see a test case...
> 
> I gave one in the thread...

No, you gave an example, not a test case :-)  A test case is something
which can be compiled, and produces assembly which can at least be
hand-inspected to understand the problem.  For instance, what is the
exact assembly instruction that you're saying is a problem?

-- 
Daniel Jacobowitz


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