From owner-freebsd-hackers Thu Sep 19 00:32:09 1996 Return-Path: owner-hackers Received: (from root@localhost) by freefall.freebsd.org (8.7.5/8.7.3) id AAA19001 for hackers-outgoing; Thu, 19 Sep 1996 00:32:09 -0700 (PDT) Received: from mail.crl.com (mail.crl.com [165.113.1.22]) by freefall.freebsd.org (8.7.5/8.7.3) with SMTP id AAA18912 for ; Thu, 19 Sep 1996 00:31:57 -0700 (PDT) Received: from root.com (implode.root.com) by mail.crl.com with SMTP id AA09720 (5.65c/IDA-1.5 for ); Thu, 19 Sep 1996 00:32:31 -0700 Received: from localhost (localhost [127.0.0.1]) by root.com (8.7.5/8.6.5) with SMTP id AAA01730; Thu, 19 Sep 1996 00:30:36 -0700 (PDT) Message-Id: <199609190730.AAA01730@root.com> X-Authentication-Warning: implode.root.com: Host localhost [127.0.0.1] didn't use HELO protocol To: hm@kts.org Cc: durian@plutotech.com, msmith@atrad.adelaide.edu.au, freebsd-hackers@FreeBSD.org Subject: Re: Special Cycles on the PCI bus In-Reply-To: Your message of "Thu, 19 Sep 1996 07:29:39 +0200." From: David Greenman Reply-To: dg@root.com Date: Thu, 19 Sep 1996 00:30:36 -0700 Sender: owner-hackers@FreeBSD.org X-Loop: FreeBSD.org Precedence: bulk >David Greenman wrote: > >> Perhaps they are caused by the inb(0x84)'s that are used as time delays in >> a couple places of the kernel. The inb(0x84) is supposed to be an unused port >> and thus should take about 1.25us to read from. This isn't always true, >> however, as people have pointed out in the past. We should probably replace >> the last few places where these are used with a calibrated wait loop. > >And then the old question appears again - how to do (relatively) precise >delays in the range of 1 us ... 10 us. As far as i understood Bruce that >time, DELAY isn't able to handle this precisely. Has that changed ? Right, this is one of the problems that needs to be resolved first. -DG David Greenman Core-team/Principal Architect, The FreeBSD Project