From owner-freebsd-alpha Wed May 15 6:40: 1 2002 Delivered-To: freebsd-alpha@freebsd.org Received: from duke.cs.duke.edu (duke.cs.duke.edu [152.3.140.1]) by hub.freebsd.org (Postfix) with ESMTP id 3C14C37B403 for ; Wed, 15 May 2002 06:39:57 -0700 (PDT) Received: from grasshopper.cs.duke.edu (grasshopper.cs.duke.edu [152.3.145.30]) by duke.cs.duke.edu (8.9.3/8.9.3) with ESMTP id JAA02112; Wed, 15 May 2002 09:39:56 -0400 (EDT) Received: (from gallatin@localhost) by grasshopper.cs.duke.edu (8.11.6/8.9.1) id g4FDdQC26760; Wed, 15 May 2002 09:39:26 -0400 (EDT) (envelope-from gallatin@cs.duke.edu) From: Andrew Gallatin MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <15586.25870.79809.901266@grasshopper.cs.duke.edu> Date: Wed, 15 May 2002 09:39:26 -0400 (EDT) To: Dag-Erling Smorgrav Cc: alpha@FreeBSD.ORG Subject: Re: memory management fault during netbooting on 4.6-PRERELEASE In-Reply-To: References: <20020514235608.A69014@xor.obsecurity.org> X-Mailer: VM 6.75 under 21.1 (patch 12) "Channel Islands" XEmacs Lucid 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 Dag-Erling Smorgrav writes: > Speaking of DHCP, can anyone explain the following: > > # /sbin/dhclient dc0 > pid 43 (dhclient): unaligned access: va=0x11fff02c pc=0x1200271d4 ra=0x1200270fc > pid 43 (dhclient): unaligned access: va=0x11fff034 pc=0x1200271d8 ra=0x1200270fc > > This is on a PWS500au running a freshly installed 5.0-DP1 (not for > long though, building world as we speak) An alpha needs to access memory in naturally aligned chunks. If a load or store is done to a misaligned address (a 32-bit load from an address starting on a 16 bit boundary, for example). These unaligned operations generate traps, and the kernel fixes up the load. This is very expensive, so the default is to print a warning when it happens. In a shell, you can use uac -s to cause programs to dump core when they generate an unaligned access, so that you can debug them. (assuming gdb worked on alpha in -current, which it doesn't; use the gdb52 port). You can also shut things up by using uac -p (or sysctl machdep.unaligned_print=0 to disable printing system wide). Drew To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-alpha" in the body of the message