Date: Wed, 8 Feb 2012 00:17:24 +0000
From: Alan Cox <alan@lxorguk.ukuu.org.uk>
To: Adam Jackson <ajax@redhat.com>
Cc: linux-kernel@vger.kernel.org, arnd@arndb.de, gregkh@linuxfoundation.org
Subject: Re: [PATCH 1/2] char/mem: Add /dev/io (v2)
Message-ID: <20120208001724.7e5c7be4@pyramind.ukuu.org.uk>
In-Reply-To: <1328657985-13942-1-git-send-email-ajax@redhat.com>
References: <1328623901-20628-1-git-send-email-ajax@redhat.com>
	<1328657985-13942-1-git-send-email-ajax@redhat.com>
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On Tue,  7 Feb 2012 18:39:45 -0500
Adam Jackson <ajax@redhat.com> wrote:

> This is like /dev/port except not broken.  /dev/port will translate all
> read/write into inb/outb streams, which is wrong since hardware can and
> does care about cycle size.  /dev/io will only allow 1, 2, or 4 byte
> access, and will translate that into the appropriate bus cycle size.

>From a security perspective /dev/[k][mem is a dumb bit of ancient Unix
history we'd dearly like to kill off. /dev/port is a similar early PC
unixism that wants to go the same way. /dev/io just adds another horror
to the pile.

Please do the decent thing, stop using /dev/mem and /dev/port for
anything. If you need to access an I/O device make it properly visible
via the kernel only for the ports and in a manner that is safe.

Alan
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