From owner-freebsd-current Mon Jul 12 11:25:42 1999 Delivered-To: freebsd-current@freebsd.org Received: from critter.freebsd.dk (critter.freebsd.dk [212.242.40.131]) by hub.freebsd.org (Postfix) with ESMTP id A457A15147 for ; Mon, 12 Jul 1999 11:25:20 -0700 (PDT) (envelope-from phk@critter.freebsd.dk) Received: from critter.freebsd.dk (localhost [127.0.0.1]) by critter.freebsd.dk (8.9.3/8.9.2) with ESMTP id UAA20503; Mon, 12 Jul 1999 20:23:26 +0200 (CEST) (envelope-from phk@critter.freebsd.dk) To: John-Mark Gurney Cc: Matthew Dillon , Luoqi Chen , dfr@nlsystems.com, jeremyp@gsmx07.alcatel.com.au, freebsd-current@FreeBSD.ORG, mike@ducky.net Subject: Re: "objtrm" problem probably found (was Re: Stuck in "objtrm") In-reply-to: Your message of "Mon, 12 Jul 1999 10:38:45 PDT." <19990712103845.39296@hydrogen.fircrest.net> Date: Mon, 12 Jul 1999 20:23:26 +0200 Message-ID: <20501.931803806@critter.freebsd.dk> From: Poul-Henning Kamp Sender: owner-freebsd-current@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG In message <19990712103845.39296@hydrogen.fircrest.net>, John-Mark Gurney writes: >Matthew Dillon scribbled this message on Jul 12: >> p.s. I'm pretty sure that the lock prefix costs nothing on a UP system, >> and probably wouldn't be noticed on an SMP system either because the >> write-allocation overhead is already pretty bad. But I haven't tested >> it. > >actually, I'm not so sure, it guarantees that NO other bus operation >will succeed while this is happening... what happens if a pci bus >mastering card makes a modification to this value? sure, it normally >won't happen, but it can... and w/o the lock prefix, this CAN happen >from what I understand of the architecture... it locks EVERYTHING. -- Poul-Henning Kamp FreeBSD coreteam member phk@FreeBSD.ORG "Real hackers run -current on their laptop." FreeBSD -- It will take a long time before progress goes too far! To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-current" in the body of the message