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Date: Tue, 18 Mar 2008 09:45:12 -0500
From: Nathan Lynch <ntl@pobox.com>
To: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Subject: Re: [PATCH v2] Force 4K pages for IO addresses.
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Cc: Olof Johansson <olof@lixom.net>, LinuxPPC-dev <linuxppc-dev@ozlabs.org>,
	Jan-Bernd Themann <themann@de.ibm.com>, Paul Mackerras <paulus@samba.org>,
	Stephen Rothwell <sfr@canb.auug.org.au>
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Benjamin Herrenschmidt wrote:
> 
> On Mon, 2008-03-17 at 19:34 -0500, Olof Johansson wrote:
> > On Mon, Mar 17, 2008 at 02:54:19PM +1100, Tony Breeds wrote:
> > > Currently HEA requires 4K pages for IO resources.  Just set the pages size to
> > > IO to 4K.
> > 
> > Well, that's too bad. Why penalize all platforms for it?
> > 
> > I.e.: Nack, we use 64K iopages on pa6t and it works well. No need to
> > waste tlb and erat space.
> 
> We would have to make that pSeries specific for now I suppose...
> 
> We don't have a way to know that there "can" be an EHEA right ? It may
> not be in the device-tree at boot and dynamically added to the
> partition...

The ibm,drc-names property of the root node should have "HEA" strings
in it on systems where EHEA can potentially be present.