ARM Cortex-A7 support in Linux
Russell King - ARM Linux
linux at arm.linux.org.uk
Fri May 17 06:55:00 EDT 2013
On Fri, May 17, 2013 at 12:47:45PM +0200, Marc Zyngier wrote:
> It depends which feature you're after. Linux supports the GIC
> virtualization extensions with KVM, for example. But we don't make any use
> of other things like priorities, split deactivation/priority drop...
Not that we could make use of priorities anymore as all interrupt handlers
are now run with IRQs disabled; an IRQ handler can't be interrupted by a
higher priority IRQ coming in.
Part of the solution to that is to go back to the original philosophy of
IRQ handling in Linux - do the least possible amount of work in the IRQ
and move the heavier stuff off into soft-IRQ context. Unfortunately,
many drivers are no longer written like that, and just do a great amount
of time consuming work in their IRQ handler.
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