Date: Thu, 03 Jan 2002 23:56:19 +0100 From: Poul-Henning Kamp <phk@critter.freebsd.dk> To: Bruce Evans <bde@zeta.org.au> Cc: Mike Silbersack <silby@silby.com>, freebsd-arch@FreeBSD.ORG Subject: Re: DELAY accuracy Re: cvs commit: src/sys/dev/usb uhci.c Message-ID: <4584.1010098579@critter.freebsd.dk> In-Reply-To: Your message of "Fri, 04 Jan 2002 09:49:03 %2B1100." <20020104094446.N18171-100000@gamplex.bde.org>
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In message <20020104094446.N18171-100000@gamplex.bde.org>, Bruce Evans writes: >On Thu, 3 Jan 2002, Poul-Henning Kamp wrote: > >> If we look at DELAY(1), which is a very common value, considering >> the typical use, I suspect it may actually be specified not for the >> delay as much for various "things to happen", things which might be >> better provoked by memory barriers or similar. >> >> Either way, in i386 I think DELAY(1) would be best implemented as >> inb(0x80) > >This mistake has been made before. inb(0x80) is too fast on some machines. Are you sure ? I have yet to see a machine where 0x80 isn't routed to hardware since it is the "magic" bios-post address... -- Poul-Henning Kamp | UNIX since Zilog Zeus 3.20 phk@FreeBSD.ORG | TCP/IP since RFC 956 FreeBSD committer | BSD since 4.3-tahoe Never attribute to malice what can adequately be explained by incompetence. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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