From mboxrd@z Thu Jan  1 00:00:00 1970
From: Ingo Molnar <mingo@elte.hu>
Date: Mon, 20 Jun 2011 07:31:22 +0000
Subject: Re: [PATCH 00/10] Enhance /dev/mem to allow read/write of arbitrary
Message-Id: <20110620073122.GA24716@elte.hu>
List-Id: <linux-sh.vger.kernel.org>
References: <201106171038.25988.ptesarik@suse.cz>
	<20110617093032.GA19235@elte.hu> <4DFE7FF9.9070406@gmail.com>
In-Reply-To: <4DFE7FF9.9070406@gmail.com>
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To: linux-arm-kernel@lists.infradead.org


* Ryan Mallon <rmallon@gmail.com> wrote:

> On 17/06/11 19:30, Ingo Molnar wrote:
> >* Petr Tesarik<ptesarik@suse.cz>  wrote:
> >
> >>This patch series enhances /dev/mem, so that read and write is
> >>possible at any address. The patchset includes actual
> >>implementation for x86.
> >This series lacks a description of why this is desired.
> >
> >My strong opinion is that it's not desired at all: /dev/mem never
> >worked beyond 4G addresses so by today it has become largely obsolete
> >and is on the way out really.
> >
> >I'm aware of these current /dev/mem uses:
> >
> >  - Xorg maps below 4G non-RAM addresses and the video BIOS
> >
> >  - It used to have some debugging role but these days kexec and kgdb
> >    has largely taken over that role - partly due to the 4G limit.
> >
> >  - there's some really horrible out-of-tree drivers that do mmap()s
> >    via /dev/mem, those should be fixed if they want to move beyond
> >    4G: their char device should be mmap()able.
> 
> There are drivers where this makes sense. For example an FPGA 
> device with a proprietary register layout on the memory bus can be 
> done this way. [...]

So you want us to help vendors screw users with insane, proprietary, 
user-space drivers with sekrit binary blobs?

Wow.

Thanks,

	Ingo