Re: No user space access during irq?

Mon, 8 Feb 1999 11:40:23 +0100 (CET)

On Mon, 8 Feb 1999, Till Harbaum wrote:

> I know i am not allowed to call the scheduler during the irq. Is
> there another way of gaining access to the correct user space?

The hard way is to make your device mmap()-able and lock (& make present)
the pages whenever you start IO, and save the (address)->(page_struct *)
for the IRQ handler. The IRQ handler is free to access a page-cache page
that is locked. The easier way (if your semantics allow this) is to shape
your device as a block-device. The hacky way is to ioremap() it and make
it's pages visible to user-space (ie. everybody in the system), this is a
security hole but might be the easiest solution for special isolated

-- mingo

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