Re: Is it useful to support user level drivers

Alan Cox (alan@lxorguk.ukuu.org.uk)
Thu, 21 Jun 2001 18:27:14 +0100 (BST)

> (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

You have to handle that in kernel space, at least enough to handle the
irq event, ack it and queue the data

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