From owner-freebsd-hackers Fri May 21 9: 9: 8 1999 Delivered-To: freebsd-hackers@freebsd.org Received: from dingo.cdrom.com (castles521.castles.com [208.214.165.85]) by hub.freebsd.org (Postfix) with ESMTP id DB05B15986 for ; Fri, 21 May 1999 09:09:04 -0700 (PDT) (envelope-from mike@dingo.cdrom.com) Received: from dingo.cdrom.com (localhost.cdrom.com [127.0.0.1]) by dingo.cdrom.com (8.9.3/8.8.8) with ESMTP id JAA00852; Fri, 21 May 1999 09:04:58 -0700 (PDT) (envelope-from mike@dingo.cdrom.com) Message-Id: <199905211604.JAA00852@dingo.cdrom.com> X-Mailer: exmh version 2.0.2 2/24/98 To: Ladavac Marino Cc: "'Mike Smith'" , Joel Ray Holveck , Doug Rabson , Peter Wemm , Tommy Hallgren , freebsd-hackers@FreeBSD.ORG Subject: Re: Lazy SPLs In-reply-to: Your message of "Fri, 21 May 1999 10:07:24 +0200." <55586E7391ACD211B9730000C1100276179612@r-lmh-wi-100.corpnet.at> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Date: Fri, 21 May 1999 09:04:57 -0700 From: Mike Smith Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG > > Level-triggered interrupts are persistent conditions, not queueable > > events. They typically require device-driver level intervention to be > > > > cleared. This is a major error in the PCI design (no surprises > > there). > > > [ML] Whoa there! That's the MAJOR advantage of PCI design. > Open collector, active low, level triggered interrupts are the only > possibility for interupt line sharing without programmatically > accessible registers on card which say "yes, I am still interrupting". For a simplistic bus, perhaps. But an arbitrated token-delivery interrupt buslet with a bus-standardised interrupt state acknowledgement protocol would be much more efficient. PCI makes too many compromises to the PC's architecture; we're just about ready for a new bus again. > Active high, edge triggered interrupts are an abomination (there > is no way to reliably share the interrupt line and you cannot even wire > or it). They are the reason why one never has enough interrupt lines on > ISA. I don't believe I ever suggested that this was the only alternative technique, and I'm certainly on record as not liking it either. -- \\ The mind's the standard \\ Mike Smith \\ of the man. \\ msmith@freebsd.org \\ -- Joseph Merrick \\ msmith@cdrom.com To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message