Re: Is it useful to support user level drivers

[Balbir Singh]

Thanks folks, I got some great comments, pointers a
list of problems which I need to take care of.
I promise that when I try and implement user
level interrupts - it won't be a hack, all problems
will be taken  care of based on good programming
practices.

I will look into the steps provided by people.
Yes! we need to worry about shared interrupts, I will
draw out a more detailed plan of problems and
solutions.

Later ...

Thanks,
Balbir

--- "Dmitry A. Fedorov" <[e-mail]>
wrote:
> On Thu, 21 Jun 2001, Oliver Neukum wrote:
> 
> > > > In addition, how do you handle shared
> interrupts ?
> > >
> > > It is impossible, see my another message.
> > 
> > Which IMHO makes the concept pretty much useless.
> > Interrupt sharing is pretty much the norm today.
> And there is no evidence for 
> > this to change in the near future. Rather the
> opposite seems to happen in 
> > fact.
> > 
> > Which devices were you thinking of, that need a
> hardware IRQ and no kernel 
> > driver ?
> 
> An ISA cards, mostly for data acquisition - edge
> triggered interrupts,
> no ack required immediately from interrupt handler.
> Rest of hardware
> handling can be deferred to user space.
> IRQ sharing is possible there in spite of some
> hardware hacking.
> 
> Yes, it is very limited range of hardware today but
> it exists
> and /dev/irq kernel module provide one of generic
> mechanisms for user
> space driver implementation.
> 

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