Date: Thu, 24 Sep 1998 19:56:47 -0400 (EDT) From: Simon Shapiro <shimon@simon-shapiro.org> To: Mike Smith <mike@smith.net.au> Cc: current@FreeBSD.ORG, bde@FreeBSD.ORG, "Justin T.Gibbs" <gibbs@plutotech.com> Subject: Re: options DPT_LOST_IRQ Message-ID: <XFMail.980924195647.shimon@simon-shapiro.org> In-Reply-To: <199809242030.NAA00623@dingo.cdrom.com>
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Mike Smith, On 24-Sep-98 you wrote: > > >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. I do not know about Evil, but I have a dislike for undeterministic systems... > > > -- > \\ 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 Sincerely Yours, Shimon@Simon-Shapiro.ORG 770.265.7340 Simon Shapiro Unwritten code has no bugs and executes at twice the speed of mouth To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message
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