Date: Thu, 24 Sep 1998 13:30:22 -0700 From: Mike Smith <mike@smith.net.au> To: "Justin T. Gibbs" <gibbs@plutotech.com> Cc: bde@FreeBSD.ORG, current@FreeBSD.ORG Subject: Re: options DPT_LOST_IRQ Message-ID: <199809242030.NAA00623@dingo.cdrom.com> In-Reply-To: Your message of "Thu, 24 Sep 1998 12:30:29 MDT." <199809241837.MAA28761@pluto.plutotech.com>
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> >This option is necessary due to interrupts being eaten by the serial > >driver 'fast interrupt' code (which in some cases blocks interrupts > >longer than the DPT assert them). > > Wow. I thought that the fast interrupt code could only cause interrupts > to be deferred, never eaten. Did anyone ever talk to Bruce about this? > I'd hate to have a situation where lots of drivers each have their own > little timeout handler to deal with this problem. Yes; the FAST_INTR() code basically looks like: fastintr: <- entry with PSL_I clear, interrupts masked call handler <- handler runs with interrupts masked sti <- reenable interrupts rti (I've left a lot out, obviously.) I actually thought as you did when I read Eivind's mail, but rereading the code this is actually the case. For all their efficiency benefits, I think fast interrupts are Evil. -- \\ 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-current" in the body of the message
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