From owner-freebsd-current Sun Feb 17 15:54:11 2002 Delivered-To: freebsd-current@freebsd.org Received: from apollo.backplane.com (apollo.backplane.com [216.240.41.2]) by hub.freebsd.org (Postfix) with ESMTP id E32ED37B400; Sun, 17 Feb 2002 15:54:06 -0800 (PST) Received: (from dillon@localhost) by apollo.backplane.com (8.11.6/8.9.1) id g1HNs6407707; Sun, 17 Feb 2002 15:54:06 -0800 (PST) (envelope-from dillon) Date: Sun, 17 Feb 2002 15:54:06 -0800 (PST) From: Matthew Dillon Message-Id: <200202172354.g1HNs6407707@apollo.backplane.com> To: Michael Smith Cc: Poul-Henning Kamp , Bruce Evans , freebsd-current@FreeBSD.ORG Subject: Re: ACPI patch (was Re: 'microuptime() went backwards ...' using ACPI...) References: <200202172349.g1HNnWA01995@mass.dis.org> Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.ORG : :I have some reservations about this, because I'm not sure that 10 :successive reads will catch the ripple-counter problem that the old PIIX4s :have. Just goes to show that I need to document my code :-) Those reads are not detecting the ripple-counter problem, they are figuring out the mask required to guarentee that two successive reads will return the same counter value so the counter read in the later code doesn't end up in an infinite loop. i.e. on a slow cpu the mask might have to remove more bits because the counter increments a number of times between reads. On a fast cpu, fewer bits would have to be chopped off. That's all. :I'd also like to see the description include the number of bits, rather :than the mask, if we are using a mask. : :Thanks for taking the time to track this one down. Well, I don't want to spend too much time on it because this was incidental to other work I'm doing on -current. If you think it's worth comitting I'll commit it, otherwise you can use it as a template for your own fix/commit. It would be nice if some sort of solution were comitted to the tree relatively soon. -Matt Matthew Dillon To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message