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Subject: Re: [PATCH 6/8] 8xx: Add missing Guarded setting in DTLB Error.
From: Benjamin Herrenschmidt <benh@kernel.crashing.org>
To: Joakim Tjernlund <joakim.tjernlund@transmode.se>
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Date: Mon, 12 Oct 2009 16:46:14 +1100
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Cc: Scott Wood <scottwood@freescale.com>,
	"linuxppc-dev@ozlabs.org" <linuxppc-dev@ozlabs.org>,
	Rex Feany <RFeany@mrv.com>
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On Mon, 2009-10-12 at 07:36 +0200, Joakim Tjernlund wrote:
> Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote on 12/10/2009 00:44:56:
> > On Mon, 2009-10-12 at 00:19 +0200, Joakim Tjernlund wrote:
> > >
> > > I hear you, I can remove DTLB error with an add on patch later if that is OK?
> > > I cannot remove the DARFix though, when I move that to do_page_fault(), I get
> > > duplicate TLB hits on the same insn. It is like when transfer_to_handler()
> > > executes rfi, the cpu restarts the the faulting insn instead of jumping
> > > to the page fault handler, not always but often.
> >
> > I'm not sure what you mean here ...
> 
> Just that I need to keep the DAR fix for dcbX insn in the DTLB handler. If I try
> to move it to do_page_fault() I get a lot more DTLB errors for dcbX insn.

I'm not sure why (ie, I didn't get your explanation about rfi and
restarting the faulting insn etc...) but ok, I don't mind having
the DAR fixup remain in the asm. It's the whole logic that looks
at the PTE and does things with it that I feel has no room in there :-)

BTW. Maybe the do_page_fault() thing comes from the fact that we
also go there via ITLB Error which doesn't set the DAR and
that's normal ?

Cheers,
Ben.