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Re: [GIT PATCH] UIO patches for 2.6.21

From:  Andrew Morton <>
To:  Greg KH <>
Subject:  Re: [GIT PATCH] UIO patches for 2.6.21
Date:  Fri, 27 Apr 2007 16:04:25 -0700
Cc:  Linus Torvalds <>,,, Benedikt Spranger <>, "Hans J. Koch" <>
Archive-link:  Article, Thread

On Fri, 27 Apr 2007 15:49:57 -0700
Greg KH <> wrote:

> Here are the updated UIO (Userspace I/O driver framework) patches for
> 2.6.21.

I'm a bit uncertain about the whole UIO idea, really.  I have this vague
feeling that we'd prefer to encourage people to move device drivers into
GPL'ed kernel rather than encouraging them to do closed-source userspace
implementations which will probably end up being slower, less reliable and
unavailable on various architectures, distros, etc.

But I don't think I have the capacity to actually think about this further
- just tossing it out there ;)

> They have been revamped from the last time you have seen them, and they
> include a real driver, the Hilscher CIF DeviceNet and Profibus card
> controller, which is being used in production systems with this driver
> framework right now.  The kernel driver they replaced was a total mess,
> with over 60+ ioctls to try to control the different aspects of the
> device.  See the last patch in this series for more details on this
> driver.
> These patches include full documentation, are self-contained from the
> rest of the kernel, and have been in the -mm tree for the past few
> months with no complaints.
> Please pull from:
> Patches will be sent as a follow-on to this message to lkml for people
> to see.
>  drivers/uio/uio_cif.c                 |  156 ++++++++

eh?  How come a particular device requires 156 lines of kernel code to
support a userspace driver?  Doesn't that kind of defeat the point?

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