Date: Wed, 01 Jul 1998 15:54:29 -0700 From: Mike Smith <mike@smith.net.au> To: "Larry S. Lile" <lile@stdio.com> Cc: Mike Smith <mike@smith.net.au>, hackers@FreeBSD.ORG Subject: Re: Problems with irq 9(2)? Message-ID: <199807012254.PAA01785@dingo.cdrom.com> In-Reply-To: Your message of "Wed, 01 Jul 1998 15:58:26 EDT." <Pine.SUN.3.91.980701155042.13549E-100000@heathers2.stdio.com>
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> > > On Wed, 1 Jul 1998, Mike Smith wrote: > > > > > > > Does anybody know if there are problems with interrupt blocking > > > when using interrupt 9(2)? I am having problems with my token > > > ring card getting into a user blocked interrupt state and cannot > > > figure out what to do. This is really screwing up my token > > > ring driver development. > > > > Larry; I meant to get back to you on this earlier, but your previous > > message is still buried. > > > > The short answer is that you can't "block" ISA interupts, so the > > problem you're seeing has to be related to how you're talking to the > > card. The only confirmation of interrupt delivery that the card will > > ever get has to come from your code. > > I thought that was the entire purpose behind splxxx(), It held off > the 8259's until the kernel could process the next interrupt. *confused* No. Interrupts are never masked in the 8259 (too expensive). But even if they were, your card has no way of knowing what has happened to the interrupt. > Anyway, the card has a register (isrp) that has a bit that shows whether > or not the card can interrrupt the 8259 on its irq line. This works for > the first interrupt but as soon as I enter an spl loop that bit goes > high, saying he can't interrupt, and never drops even after exiting the > spl loop. The ISA interrupt protocol is one-sided, so there's no way that it could know anything about whether it can or can't interrupt. -- \\ Sometimes you're ahead, \\ Mike Smith \\ sometimes you're behind. \\ mike@smith.net.au \\ The race is long, and in the \\ msmith@freebsd.org \\ end it's only with yourself. \\ msmith@cdrom.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message
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