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Date: Mon, 18 Feb 2008 13:04:22 -0800
From: Arjan van de Ven <arjan@infradead.org>
To: Jean Delvare <khali@linux-fr.org>
Subject: Re: [Patch 0/2] powerpc: avoid userspace poking to legacy ioports
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Cc: parabelboi@bopserverein.de, linux-kernel@vger.kernel.org,
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On Mon, 18 Feb 2008 21:58:42 +0100
Jean Delvare <khali@linux-fr.org> wrote:

> On Tue, 19 Feb 2008 07:42:03 +1100, Benjamin Herrenschmidt wrote:
> > 
> > > Maybe Christian's patch can be improved to not do the check on
> > > these? As long as /dev/port exists, it seems reasonable that the
> > > kernel should behave, no matter what I/O ports are accessed from
> > > user-space.
> > 
> > nonsense.
> > 
> >  /dev/mem exists for example, but you are still not supposed to go
> > bang all over the place in it.
> 
> You should at least be able to read from it without crashing the
> machine. Of course writing is a different story.

keep dreaming. This is not how /dev/mem works today, not on x86 and very likely not on ppc either.