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

[Jidong Xiao]

On Wed, Feb 22, 2012 at 11:56 PM, Jidong Xiao <jidong.xiao@xxxxxxxxx> wrote:
> Hi,
>
> I am just curious. Since the concept user-space device drivers has
> been proposed for several years, and some related projects and
> research papers have demonstrated the feasibility of of moving device
> drivers into use space. In particular, this paper:
>
> Tolerating Malicious Device Drivers in Linux.
> http://pdos.csail.mit.edu/papers/sud:usenix10.pdf
>
> In this paper, existing device driver code need not to be changed,
> which should help the idea to be applied in practice.
>
> The advantage and disadvantage of move device drivers into use space
> of both obvious:
>
> Advantage: Since most of kernel bugs are caused by device drivers
> issues, moving device drivers into user space can reduce the impact of
> device driver bugs. From security perspective, the system can be more
> secure and robust if most device drivers are working in user space.
> Disadvantage: At least, existing techniques as well as the above paper
> showed a relatively high overhead.
>
> So is it mainly because the high overhead that prevents the user-space
> device drivers ideas being accepted in Linux?
>

Actually, my major concern is, since UIO has been accepted, then why
don't we move all the rest device drivers into user space as well. As
I understand, currently, some of device drivers are running on user
space, while the other (or say the majority of) device drivers are
running on kernel space, so why don't we maintain a consistent device
drivers infrastructure, say, either all in user space, or all in
kernel space. (Sure some critical device drivers still need to be kept
in kernel space.)

-Jidong
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