Re: [PATCH 2/3] UIO: Documentation

[Jesper Juhl]

On 09/08/07, Greg KH <gregkh@xxxxxxx> wrote:
> On Thu, Aug 09, 2007 at 01:03:39AM +0200, Jesper Juhl wrote:
> > >
> > I think the only way to avoid it is to not provide something like UIO.
>
> Problem is, things like UIO provide a real solution for a wide range of
> different types of devices.  Like the one provided in the kernel right
> now, and a bunch of others that I am currently discussing with different
> manufacturers (think high-speed DSPs that just want to give userspace
> direct access to the card and have the kernel get the hell out of the
> way so data can be read and processed as fast as possible.)
>
Please understand that I'm not saying UIO isn't potentially useful,
nor am I saying that it won't potentially give us support for a bunch
of new hardware.  All I'm trying to say is that, to me at least, it is
trying to buy us those new drivers in a way that encourages creating
those drivers as closed source software- *that* is all I'm having
issues with - that is what I think is a step backwards - something
that may give us a short-term gain but will make us lose out
long-term.

> And also realize that some types of systems have been doing this very
> same kind of kernel/userspace interface for many years, namely X :)
>
That something has been going on for years doesn't in itself make it a
good argument for that model.  ;-)

> As for the legalities of using closed source userspace code with the UIO
> interface, consult a lawyer if you have questions, and be sure to bring
> up Alan's comments about derivative works :)
>
I'm not arguing against closed source applications in userspace. That
is of course OK. What I'm arguing about is a kernel interface that
encourages closed source (userspace) *drivers*.

-- 
Jesper Juhl <jesper.juhl@xxxxxxxxx>
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