From: Matt Sealey <matt@genesi-usa•com>
To: benh@kernel•crashing.org
Cc: linuxppc-dev@ozlabs•org, "Régis Odeyé" <regis.odeye@kontron•com>
Subject: Re: Extended Addressing Mode
Date: Wed, 22 Oct 2008 17:21:09 -0500 [thread overview]
Message-ID: <48FFA755.5050808@genesi-usa.com> (raw)
In-Reply-To: <1224713506.7654.353.camel@pasglop>
Benjamin Herrenschmidt wrote:
> On Wed, 2008-10-22 at 08:08 -0500, Kumar Gala wrote:
>>> We are developing a board based on Freescale 8641D which can get
>> 4GB
>>> of ram. So I need 4GB+IOs (~1GB) of physical addressing space.
>>> My plan is to put a part of this ram above of 4GB to keep accesses
>>> to the IOs below the 4GB limit. It means non-contiguous ram
>>> addressing and XAEN features to be working.
>
> Why would you put the IOs below the 4G point ? It's actually easier
> to have the IOs up above, like a lot of 4xx do.
Because we're Genesi! And we have a firmware solution that
kind of has to keep 32-bit pointers in the unlikely event that
someone actually uses the client interface (besides yaboot!).
Having I/O in the 36-bit range could cause all sorts of
explosions, and we're running real-mode so trapping and faking
I/O accesses is REALLy difficult :}
--
Matt Sealey <matt@genesi-usa•com>
Genesi, Manager, Developer Relations
next prev parent reply other threads:[~2008-10-22 22:21 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2008-10-22 8:59 Extended Addressing Mode Régis Odeyé
2008-10-22 12:31 ` Kumar Gala
2008-10-22 12:59 ` Régis Odeyé
2008-10-22 13:08 ` Kumar Gala
2008-10-22 13:40 ` Régis Odeyé
2008-10-22 13:42 ` Matt Sealey
2008-10-22 14:06 ` Kumar Gala
2008-10-22 14:19 ` Matt Sealey
2008-10-22 14:58 ` Kumar Gala
2008-10-22 18:11 ` Matt Sealey
2008-10-22 19:59 ` Becky Bruce
2008-10-22 22:18 ` Matt Sealey
2008-10-22 14:22 ` Matt Sealey
2008-10-22 14:59 ` Kumar Gala
2008-10-22 18:25 ` Matt Sealey
2008-10-22 14:18 ` Régis Odeyé
2008-10-22 22:11 ` Benjamin Herrenschmidt
2008-10-22 22:21 ` Matt Sealey [this message]
2008-10-22 22:48 ` Benjamin Herrenschmidt
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