linux-kernel - Re: Can we move device drivers into user-space?

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Message-ID: <20120226015820.GB18931@gallifrey>
Date:	Sun, 26 Feb 2012 01:58:20 +0000
From:	"Dr. David Alan Gilbert" <linux@...blig.org>
To:	Mauro Carvalho Chehab <mchehab@...hat.com>
Cc:	Eduard - Gabriel Munteanu <eduard.munteanu@...ux360.ro>,
	Jidong Xiao <jidong.xiao@...il.com>, david@...g.hm,
	Cong Wang <xiyou.wangcong@...il.com>,
	Kernel development list <linux-kernel@...r.kernel.org>
Subject: Re: Can we move device drivers into user-space?

* Mauro Carvalho Chehab (mchehab@...hat.com) wrote:
> Em 25-02-2012 13:10, Eduard - Gabriel Munteanu escreveu:
> > On Fri, Feb 24, 2012 at 04:21:09PM -0200, Mauro Carvalho Chehab wrote:
> >> Moving a buggy driver to userspace won't fix the bug. You're just moving
> >> it from one place to another place. Also, the code will likely require changes
> >> to work on userspace, so, the chances are that you're actually introducing more
> >> bugs.
> > 

<snip>

> >> That's said, there are much more eyes inspecting the kernel sources than on any 
> >> other userspace project. So, the risk of a bad code to be inserted unnoticed at
> >> the Linux kernel is degrees of magnitude lower than on an userspace driver.
> > 
> > Those much more eyes have already missed important bugs in the past.
> 
> Yes, nobody is perfect. But the probability that something passes on a 4000+ people
> review is lower than the probability of a bug on a piece of code where just one 
> or two people are looking on it.

That there are 4000+ people reading a driver is a big assumption; for common
drivers I'd agree - one problem though is there are a lot of drivers for obscure
hardware or old/dead hardware/protocols that frankly near to nobody cares about.

Very few people read those drivers; yet sometimes they get built and distributed
and someone then finds that since no one has looked at them they're full of holes,
and given a malicious USB device for example, you can suddenly create one of these
devices that only 3 people have bothered to read the source to - 5 years ago.
(The Econet security bug recently would be an example of that).

There is a line which says that things that really aren't used
just shouldn't be built; but then there are things that are only used
by a few people, and then ones only used by a few organisations - and
it gets very difficult to say at what point you say just turn it off.

Dave
-- 
 -----Open up your eyes, open up your mind, open up your code -------   
/ Dr. David Alan Gilbert    |       Running GNU/Linux       | Happy  \ 
\ gro.gilbert @ treblig.org |                               | In Hex /
 \ _________________________|_____ http://www.treblig.org   |_______/
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