Change mode to kernel?

Jeff Noxon (jeff@planetfall.com)
Tue, 19 May 1998 11:19:08 -0500

Is it possible for user code to change to kernel mode and back? Or is
that something that only VMS can do? :)

I want to write a simple device driver that doesn't require IRQs or DMAs,
and I'd rather not do the dirty part as a kernel module. Certain I/O
operations need to be atomic to avoid races with other code tweaking the
same hardware. I understand (possibly incorrectly) that it isn't safe
(or possible) to disable IRQs in userland...

What's the best approach?

Thanks in advance,

Jeff

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