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Message-ID: <20061214111439.11bed930@localhost.localdomain>
Date: Thu, 14 Dec 2006 11:14:39 +0000
From: Alan <alan@...rguk.ukuu.org.uk>
To: "Hua Zhong" <hzhong@...il.com>
Cc: "'Martin J. Bligh'" <mbligh@...igh.org>,
"'Linus Torvalds'" <torvalds@...l.org>,
"'Greg KH'" <gregkh@...e.de>, "'Jonathan Corbet'" <corbet@....net>,
"'Andrew Morton'" <akpm@...l.org>,
"'Michael K. Edwards'" <medwards.linux@...il.com>,
<linux-kernel@...r.kernel.org>
Subject: Re: GPL only modules [was Re: [GIT PATCH] more Driver core patches
for 2.6.19]
On Wed, 13 Dec 2006 22:01:15 -0800
"Hua Zhong" <hzhong@...il.com> wrote:
> > I think allowing binary hardware drivers in userspace hurts
> > our ability to leverage companies to release hardware specs.
>
> If filesystems can be in user space, why can't drivers be in user space? On what *technical* ground?
The FUSE file system interface provides a clean disciplined interface
which allows an fs to live in user space. The uio layer (if its ever
fixed and cleaned up) provides some basic hooks that allow a user space
program to arbitarily control hardware and make a nasty undebuggable mess.
uio also doesn't handle hotplug, pci and other "small" matters.
Now if you wanted to make uio useful at minimum you would need
- PCI support
- The ability to mark sets of I/O addresses for the card as
"unmappable", "read only", "read-write", "any read/root write", "root
read/write"
- A proper IRQ handler
- A DMA interface
- The ability to describe sharing rules
Which actually is a description of the core of the DRM layer.
-
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