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Date: Thu, 30 Oct 2008 16:36:45 -0400
From: Josh Boyer <jwboyer@linux.vnet.ibm.com>
To: benh@kernel.crashing.org
Subject: Re: 44x _tlbie() ME/CE/DE disabling unnecessary?
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Cc: linuxppc-dev@ozlabs.org, David, Gibson <david@gibson.dropbear.id.au>,
	Hollis Blanchard <hollis@penguinppc.org>
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On Fri, 31 Oct 2008 07:14:00 +1100
Benjamin Herrenschmidt <benh@kernel.crashing.org> wrote:

> On Thu, 2008-10-30 at 13:04 -0500, Hollis Blanchard wrote:
> > 
> > I don't think it's necessary at all to disable ME/CE/DE inside
> > _tlbie() on 440, because the interrupt handlers for those types save
> > and restore MMUCR (they're all the same code path; see
> > mcheck_transfer_to_handler in entry_32.S).
> 
> This was written before the saving of MMUCR was added I think.

I was thinking that but git was being annoying.

> > However, I think EE does need to be disabled, since the normal EE
> > handler doesn't deal with MMUCR. So instead of all these MSR
> > manipulations, I think a simple wrteei 0/1 pair should do the trick?
> > Or maybe mfmsr/wrteei/wrtee, in case _tlbie() happens to be called
> > with interrupts disabled already.
> 
> Yes.

Agreed.  Hollis and I had this discussion on IRC and I pointed out that
the patch originally just started with wrteei's.

(And aren't you supposed to be on vacation...)

josh