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Date:      Thu, 22 Jul 1999 17:57:23 -0500 (CDT)
From:      "Christopher W. Banek" <unixboy@imsa.edu>
To:        Matthew Dillon <dillon@apollo.backplane.com>
Cc:        freebsd-smp@FreeBSD.ORG
Subject:   Re: Page Fault Problems with SMP kernel in 3.2-RELEASE
Message-ID:  <Pine.SOL.4.02.9907221755550.27378-100000@coke>
In-Reply-To: <199907222220.PAA88210@apollo.backplane.com>

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On Thu, 22 Jul 1999, Matthew Dillon wrote:

> :Hi.  I am a a bit new to FreeBSD, came over from linux, but here is what
> :is happening.  I installed 3.2-RELEASE and everything went fine.  I
> :compilied an SMP kernel and now it page faults when ever I am doing
> :something system intensive.  It happens during configure scripts, but not
> :when I do a make.  But if I do a make -j2, it crashes quickly.
> :
> :Oh yeah, I have a GA-686LX2 with Dual PII/333 and 128MB of Ram.
> 
>     There's a good chance the problem has been fixed in FreeBSD-STABLE
>     (i.e. changes made since the 3.2 release), but it's hard to tell 
>     from the information you provided.
> 
>     There are two ways to get additional information:
> 
>     * Try to get the kernel to generate a kernel core dump
> 
> 	This involves having a swap area that is at least as large as 
> 	main memory.
> 
> 	Setting the dumpdev in /etc/rc.conf correctly.  If you have IDE
> 	disks it might be something like I show below.  Note that you
> 	have to be careful to specify the correct partition name.  Swap
> 	partitions almost always end with 'b'.
> 
> 	    dumpdev="/dev/wd0b"
> 
> 	Ensuring that /var/crash exists and has enough free space to hold
> 	the dump (at least as much space as you have main memory, plus a
> 	couple of megabytes more).  You can make /var/crash a softlink to
> 	some other partition if /var doesn't have enough space.  For example
> 	you can create a /usr/crash and then remove /var/crash and create
> 	a softlink 'ln -s /usr/crash /var/crash'.
> 
> 	Once these changes are made and you reboot, the next time the machine
> 	crashes it should be able to generate a kernel core.  You can then
> 	gdb the core like this:
> 
> 		cd /var/crash
> 		ls -la
> 		gdb -k kernel.0 vmcore.0		(or whatever
> 						the names wind up being)
> 		back					(to get a backtrace)
> 
>     * Recompile the kernel with the DDB option turned on.  Now when the
>       kernel crashes it will drop into a DDB> prompt and you should be
>       able to do a 'trace' to get a call stack backtrace from which we
>       may be able to get more information.  (Then type 'panic' and hit
>       return a couple of times to panic the system).
> 
> 	  Recompiling the kernel for someone who has never done it before
> 	  can take a bit of work.
> 
> 
>     If the problem has already been solved you will have to learn how to 
>     download the latest source dist in order to recompile a new kernel.
> 
>     Take a look at the FreeBSD documentation, especially the handbook. 
>     See http://www.freebsd.org/
> 
> 					-Matt
> 					Matthew Dillon 
> 					<dillon@backplane.com>
> 
> :Here is the exact error message.
> :
> :Fatal trap 12: page fault while in kernel mode
> :mp_lock = 01000002; cpuid=1; lapic.id=01000000
> :fault virtual address     = 0x2b
> :fault code                = supervisor read, page not present
> :instruction pointer       = 0x8:0xc01cb3ab
> :stack pointer  		  = 0x10:0xc4a41e40
> :frame pointer		  = 0x10:0xc4a41e4c
> :code segment		  = base 0x0, limit 0xfffff, type ox1b
> :		 	  = DPL 0, pres1, def32, gran 1
> :processor eflags	  - interrupt enabled, resume,IOPL =  0
> :current process		  = 2800 (sh)
> :inturrupt mask		  = net tty bio cam <- SMP: XXX
> :trap number		  = 12
> :panic: page fault
> :mp_lock = 01000002; cpuid = 1; lapic.id = 01000000
> :boot() called on cpu#1
> :
> :
> :Thanks for any help you guys can provide.
> :Christopher Banek
> :
> :
> :
> :
> :To Unsubscribe: send mail to majordomo@FreeBSD.org
> :with "unsubscribe freebsd-smp" in the body of the message
> :
> 

I have done all of the things that you said, but when I recompiled the
kernel with debugger support enabled, now it doesn't page fault, it just
freezes with no messages at all.  And no core dumps are being made.

I am totally clueless about this one.

Christopher Banek




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