Date: Thu, 17 Jun 2004 17:01:07 +1000 (EST) From: Bruce Evans <bde@zeta.org.au> To: Roman Kurakin <rik@cronyx.ru> Cc: freebsd-current@freebsd.org Subject: Re: How to catch interrupt Message-ID: <20040617164703.H2144@gamplex.bde.org> In-Reply-To: <40D0CABA.1020101@cronyx.ru> References: <40D070B7.5000009@cronyx.ru> <20040617080547.F8883@gamplex.bde.org> <40D0CABA.1020101@cronyx.ru>
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On Thu, 17 Jun 2004, Roman Kurakin wrote: > Bruce Evans: > >However, you may only need to test for pending interrupts. This can > >be done for isa interrupts using isa_irq_pending() to get a bitmap of > > > It seems that this function is not working for interrupts that were > already used > by some driver before I call it. It only works for unacknowledged interrupts, so it can only work for masked interrupts. See sio.c: % /* % * We don't want to get actual interrupts, just masked ones. % * Interrupts from this line should already be masked in the ICU, % * but mask them in the processor as well in case there are some % * (misconfigured) shared interrupts. % */ % mtx_lock_spin(&sio_lock); Note that masking interrupts in the processor only helps for the non-SMP case, and the comment has rotted: - the code acquires a spinlock. It only masks interrupts as a BAD side effect. In my version, acquiring a spinlock doesn't mask processor interrupts, and there is an explicit intr_disable(). - interrupts can now be shared in some non-misconfigured cases. Bruce
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