On Fri, Sep 21, 2007 at 01:38:34AM -0500, Hollis Blanchard wrote:
> On Fri, 2007-09-21 at 15:42 +1000, David Gibson wrote:
> > On Thu, Sep 20, 2007 at 10:34:12PM -0500, Hollis Blanchard wrote:
> > > I seem to have come across a strange bug while doing KVM development. It
> > > seems that the final tlbwe in finish_tlb (head_44x.S) is actually
> > > leaking RPN bits into the "attribute" word.
> > >
> > > When I set a breakpoint there and press enter on the serial console, I
> > > see r12=ef600703, which is the physical address of the UART on this chip
> > > (440EP), plus the correct permission bits at the bottom.
> > >
> > > Am I crazy? I'm not really looking to step through that assembly right
> > > now... Clearly (current) hardware is just ignoring these errant writes,
> > > but it should be fixed.
> >
> > A quick glance at the code suggests this is indeed wrong. Hurrah.
> > Another reason to rewrite the 44x tlb miss handling.
>
> Just a quick fix would be fine too... ;)
I suppose.
> I'm just glad it's not a KVM bug, because when I dumped the TLB state
> and saw bizarre values I was getting really worried.
>
> > PS. "errant" and "error" are not cognate, even if the chip doc
> > writers think so...
>
> According to Merriam Webster, errant 2c is "c : behaving wrongly <an
> errant child>", so I'm OK with it.
Good heavens. No such usage mentioned in the Shorter OED, only as in
"knight errant". You Americans and your strange language :-p.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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