Re: Discourage Uniform Driver Model

[Timothy Miller <miller@techsource.com>]

James Clark wrote:
>>How does your proposal differ/improve on the demand-load module system?
> 
> 
> Modules must be (re)compiled for each specific kernel release. This is because 
> of the very tight coupling with the kernel. The kernel changes so much that 
> it is often necessary to amend a module to keep up. My suggestion is to 
> create an abstract interface between the two. The interface (called a binary 
> interface) would define the way the two 'talk' to one another. Once the 
> interface has been released as v1.0 any module could be made compatible with 
> the v1.0 interface. After a while it would be necessary to release improved 
> interfaces. This would not break the existing modules as the old interface 
> could remain due to its abstract nature. This technique is used in everything 
> from Windows drivers, Netscape pluggins and even normal programs - image 
> saying you must buy a new version of Word Perfect for every minor release of 
> the OS - it has 'binary' compatibility. Unfortunately many see this as active 
> encouragement of 'binary only' modules which have no source code. This idea 
> would cost in performance. I suggest this loss is worthwhile to resolve 
> compatibility and usability.

I have been flamed before for "suggesting" things without code to back 
it up.  There have been lots of technical explanations given for why a 
consistent binary-only interface is impractical.  However, the idea has 
been suggested before, and some implementations have been done.  You 
should look into those.

This "suggestion" is sufficiently uninteresting to everyone that your 
suggestion will not be taken.  If you want something like this 
implemented, you're going to have to do it yourself.  That's the beauty 
of Free Software.

> 
>>  This seemed to work well in Mandrake, or am I missing the point?!?
> 
> 
> Unless you build the module yourself you are the mercy of Mandrake to make 
> each module - I don't see this as being much different from the situation 
> with Windows.  Poor old Mandrake must remake almost every module almost 
> everytime. You cannot use a module from Redhat's kernel. In effect everyone 
> is duplicating effort. Modules must currently be compiled, this requires a 
> degree of expertise and can be daunting to someone who just wants to use the 
> OS. My suggestion would not remove need to release modules in source form, 
> but once compiled they could be plugged into any kernel and distributed in 
> binary+source form. 

If everyone used the vger kernel, they wouldn't have some of these 
problems.  However, due to the way Linux strives to remain lean and 
efficient, it is technically unwise to standardize any driver interface. 
  That is the nature of the beast.  If you want to write an interposing 
layer, please feel free to do so.

> 
>>Also, the only reply to your posting that I read (and I've only read a
>>fraction of them!) which offered any genuine usefulness was the point
>>that if you offer the code then they'll consider the merits.  Are you
>>considering an actual solution, or just suggesting a policy change?
> 
> 
> I understand the way competitor binary interfaces work. Currently I'm not 
> going to roll up my sleeves and write this system. I don't have the technical 
> expertise to design such a thing and although I could learn the curve at this 
> time is too steep. I do think that my experience with similar competitor 
> systems allows me to speak on the subject. However, I feel that pushing for 
> this change is a positive thing. It has started a debate on 'misusing' the 
> GPL to prevent binary only modules and has resulted in some positive 
> comments. If they debate it  rationally and then decide not to bother I will 
> have achieved a lot. I do  feel qualified to make this (obvious) suggestion 
> and comment on the design of any resulting interface.

Yor suggestion has been listened to.  However, it has become clear that 
kernel maintainers actively dislike this idea.  Pushing it is only going 
to piss them off.