Date: Tue, 6 Oct 1998 09:28:00 +0930 From: Greg Lehey <grog@lemis.com> To: Brian Somers <brian@Awfulhak.org> Cc: iyengar <SanatanaDharma@email.msn.com>, freebsd-questions@FreeBSD.ORG Subject: Re: sio1 problem, ppp problem and 3com 3c905B-TX problem Message-ID: <19981006092800.R27781@freebie.lemis.com> In-Reply-To: <199810050941.KAA23591@woof.lan.awfulhak.org>; from Brian Somers on Mon, Oct 05, 1998 at 10:41:07AM %2B0100 References: <19981005142712.X2545@freebie.lemis.com> <199810050941.KAA23591@woof.lan.awfulhak.org>
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On Monday, 5 October 1998 at 10:41:07 +0100, Brian Somers wrote: > [.....] >> IRQ 3 is normally reserved for sio1. You can't have two sio ports on >> the same IRQ. This is a hardware limitation. > [.....] > > Hmm, I don't think it's a hardware limitation - AFAIK, it's a sio > driver limitation. > > Isn't it possible to have more than one UART generate IRQ3 and have > the driver ask each UART if it's got anything to do ? I don't know > if this IRQ/polling setup would prevent ``fast interrupt'' handling > though. No. At least in the original sio board, the interrupt line was active all the time when the interrupts were enabled. That way they saved 1/6 of an LS04 inverter chip :-) I'm pretty sure that this applies to all modern equivalents as well. If you have two ports on the same IRQ, they're both saying "I'm not interrupting", and from time one says "I'm interrupting", and it's up to their bus drivers to decide which one wins. In this case, though, I got the numbers wrong. Santana said "COM2", which I took to mean "sio2". In fact, there's only one port involved, and it's more likely that he has been given incorrect information about the I/O address. Greg -- See complete headers for address, home page and phone numbers finger grog@lemis.com for PGP public key To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-questions" in the body of the message
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