Re: Is it useful to support user level drivers

[Pavel Machek]

Hi!

> > (i.e. counted). An alternative to queuing (user selectable) is to block
> > interrupt generation at hardware level in kernel space immediately
> > before notification.
> > 
> > I'm missing something?
> 
> IRQ 9 shared between user space app and disk. IRQ arrives is disabled and
> reported, app wakes up, app wants to page in code, IRQ is disabled,
> box dies

Actually, what about specifying that your usermode app has to be
pagelocked?

Alternatively.... You *can* do disk I/O without interrupts. Just poll
your IDE controller. [I'm doing that on my velo.] Hopefully your timer
IRQ is not shared with usermode app, then :-( [but that's almost
impossible on PCs, right?].
                                                                Pavel
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