Date: Fri, 4 Jan 2002 09:49:03 +1100 (EST) From: Bruce Evans <bde@zeta.org.au> To: Poul-Henning Kamp <phk@critter.freebsd.dk> 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: <20020104094446.N18171-100000@gamplex.bde.org> In-Reply-To: <2971.1010094530@critter.freebsd.dk>
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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. Bruce To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-arch" in the body of the message
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