From mboxrd@z Thu Jan  1 00:00:00 1970
Subject: Re: [Xenomai-core] xenomai preempting interrupt handler ?
From: Philippe Gerum <rpm@xenomai.org>
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Date: Thu, 08 Mar 2007 10:42:18 +0100
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To: Steven Scholz <steven.scholz@domain.hid>
Cc: Xenomai-core@domain.hid

On Thu, 2007-03-08 at 10:29 +0100, Steven Scholz wrote:
> Hi all,
>=20
> using an oscilloscope I found that the AT91RM9200 spends up to 300=B5s in=
 the
> interrupt handler for ethernet controller.
>=20
> Now I wonder if this interrupt handler will be preempted by Xenomai if th=
ere
> is a high priority, periodic real time task?

Hw interrupts are forcibly enabled before entering any Linux IRQ
handler, exactely to prevent the issue you described (e.g. fiddling with
an IDE controller in PIO mode also gives funky latency results unless
the latter is true), so the answer is yes.

>  Thus will the duration of the
> ethernet interrupt handler add the the worst case latency?
>=20

Not from Linux IRQ handlers; you may want to check this using the
tracer. If hw interrupts are masked there, then it's a blatant bug.

> Thanks.
>=20
--=20
Philippe.