From owner-freebsd-alpha Sun Nov 10 8:15:22 2002 Delivered-To: freebsd-alpha@freebsd.org Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125]) by hub.freebsd.org (Postfix) with ESMTP id 6036E37B406; Sun, 10 Nov 2002 08:15:21 -0800 (PST) Received: from beppo.feral.com (beppo.feral.com [192.67.166.79]) by mx1.FreeBSD.org (Postfix) with ESMTP id 8217543E75; Sun, 10 Nov 2002 08:15:20 -0800 (PST) (envelope-from mjacob@feral.com) Received: from mailhost.feral.com (mjacob@mailhost.feral.com [192.67.166.1]) by beppo.feral.com (8.11.3/8.11.3) with ESMTP id gAAGEuZ59342; Sun, 10 Nov 2002 08:14:56 -0800 (PST) (envelope-from mjacob@feral.com) Date: Sun, 10 Nov 2002 08:14:55 -0800 (PST) From: Matthew Jacob X-Sender: mjacob@beppo Reply-To: mjacob@feral.com To: Doug Rabson Cc: "Alan L. Cox" , Jeff Roberson , Andrew Gallatin , alpha@FreeBSD.ORG, alc@FreeBSD.ORG, John Baldwin Subject: Re: alpha: top of tree kernel blooie In-Reply-To: <200211101110.34153.dfr@nlsystems.com> Message-ID: MIME-Version: 1.0 Content-Type: TEXT/PLAIN; charset=US-ASCII Sender: owner-freebsd-alpha@FreeBSD.ORG Precedence: bulk List-ID: List-Archive: (Web Archive) List-Help: (List Instructions) List-Subscribe: List-Unsubscribe: X-Loop: FreeBSD.org > > 2. Don't we compile by default for the older Alphas that lack byte > > manipulation instructions? Thus, a byte store is implemented by a > > read-modify-write sequence of instructions. Thus, two simultaneous > > uma_dbg_alloc()s on adjacent locations in us_freelist could cause > > corruption. > > It was exactly this kind of breakage that prompted me to write the > atomic_* functions in the first place. Note that it is often possible > to get corruption even on a UP machine if an interrupt happens mid > sequence. I survived a -j4 buildworld on the 4-way SMP with atomic_set_8 in the uma_dbg_alloc/uma_dbg_free. I think we'll call this one 'good' To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-alpha" in the body of the message