Date: Wed, 15 May 2002 09:39:26 -0400 (EDT) From: Andrew Gallatin <gallatin@cs.duke.edu> To: Dag-Erling Smorgrav <des@ofug.org> Cc: alpha@FreeBSD.ORG Subject: Re: memory management fault during netbooting on 4.6-PRERELEASE Message-ID: <15586.25870.79809.901266@grasshopper.cs.duke.edu> In-Reply-To: <xzpg00t26ia.fsf@flood.ping.uio.no> References: <20020514235608.A69014@xor.obsecurity.org> <xzpg00t26ia.fsf@flood.ping.uio.no>
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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
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