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Re: Porting To New System

To: Stanislaw Skowronek <sskowron@ET.PUT.Poznan.PL>
Subject: Re: Porting To New System
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
Date: Fri, 27 May 2005 19:13:07 +0100
Cc: Cameron Cooper <developer@phatlinux.com>, linux-mips@linux-mips.org
In-reply-to: <Pine.GSO.4.10.10505271929510.25076-100000@helios.et.put.poznan.pl>
Original-recipient: rfc822;linux-mips@linux-mips.org
References: <Pine.GSO.4.10.10505271929510.25076-100000@helios.et.put.poznan.pl>
Sender: linux-mips-bounce@linux-mips.org
On Gwe, 2005-05-27 at 18:30, Stanislaw Skowronek wrote:
> >  Does the firmware give you the ability to control MMU mappings ?
> 
> I think we won't - this would be a serious security bug.

That depends who the device is defending against and how. MMU control
cuts both ways in game consoles (if present) - it makes it harder to
defend the console from a hostile writer, but it also makes it easier
for the game authors to debug and to trap/recover from errors when the
game is deployed.

For ucLinux you essentially need a console, an input device (keyboard
etc), a storage device, the ability to allocate memory and a timer
interrupt/callback. Absolutely everything else is optional. So you can
probably run ucLinux as a 'game' which allocates lots of memory,
requests a timer callback and drives the entire world through the
firmware. Whether you can do non-ucLinux depends on MMU access and
control. If you've got some kind of MMU interface then you've probably
got sufficient to do a full Linux but ucLinux would still be a natural
stepping stone in exploration.

Alan


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