Re: kgdb on an amd64 kernel anyone?

On Jul 1, 2009, at 03:50 PM, Ian Freislich wrote:

> Hi
>
> Has anyone managed to inspect a vmcore produced by an amd64 kernel
> in the last few months?  I've had several crashes, but all the cores
> appear corrupted and no useful data can be had.
>
> The latest:
>
> [firewall2.jnb1] /var/crash # kgdb -c vmcore.5 /boot/kernel.old/kernel
> GNU gdb 6.1.1 [FreeBSD]
> Copyright 2004 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License, and  
> you are
> welcome to change it and/or distribute copies of it under certain  
> conditions.
> Type "show copying" to see the conditions.
> There is absolutely no warranty for GDB.  Type "show warranty" for  
> details.
> This GDB was configured as "amd64-marcel-freebsd"...(no debugging  
> symbols found)...
> Attempt to extract a component of a value that is not a structure  
> pointer.
> Attempt to extract a component of a value that is not a structure  
> pointer.
> Attempt to extract a component of a value that is not a structure  
> pointer.
> Attempt to extract a component of a value that is not a structure  
> pointer.
> #0  0x0000000000000000 in ?? ()
> (kgdb) bt
> #0  0x0000000000000000 in ?? ()
> Cannot access memory at address 0x0
>
> Or this followed by pages and pages stack corruption.  The most
> frames I've had the patience to scroll through like this is in the
> 0000s.
>
> [firewall1.jnb1] /var/db/firewall # kgdb -c /var/crash/vmcore.4 / 
> boot/kernel/kernel
> GNU gdb 6.1.1 [FreeBSD]
> Copyright 2004 Free Software Foundation, Inc.
> GDB is free software, covered by the GNU General Public License, and  
> you are
> welcome to change it and/or distribute copies of it under certain  
> conditions.
> Type "show copying" to see the conditions.
> There is absolutely no warranty for GDB.  Type "show warranty" for  
> details.
> This GDB was configured as "amd64-marcel-freebsd"...(no debugging  
> symbols found)...
> Attempt to extract a component of a value that is not a structure  
> pointer.
> Attempt to extract a component of a value that is not a structure  
> pointer.
> Attempt to extract a component of a value that is not a structure  
> pointer.
> Attempt to extract a component of a value that is not a structure  
> pointer.
> #0  0xffffffff802bdb8a in doadump ()
> (kgdb) bt
> #0  0xffffffff802bdb8a in doadump ()
> #1  0xffffff81a4af95f0 in ?? ()
> #2  0xffffffff802be0bb in boot ()
> #3  0xe880695fa0c7c748 in ?? ()
> #4  0x9066eaebfff07554 in ?? ()
> #5  0x31804b26a0c7c748 in ?? ()
> #6  0xc3c900033ee2e8c0 in ?? ()
> #7  0x56415741e5894855 in ?? ()
> #8  0x48fb895354415541 in ?? ()
> #9  0x253c8b486528ec83 in ?? ()
> #10 0x000119b900000000 in ?? ()
> #11 0x804b26d8c2c74800 in ?? ()
> #12 0x65ffff14b1e8f631 in ?? ()
> #13 0x00000000253c8b48 in ?? ()
> #14 0x65000235f1e8f631 in ?? ()
> #15 0x0000000025148b48 in ?? ()
> #16 0x450c608b44028b48 in ?? ()
> #17 0x000004cd840fe485 in ?? ()
> #18 0x00000025348b4865 in ?? ()
> #19 0xe80c49ff0e8b4800 in ?? ()
> #20 0x68c7c74800148304 in ?? ()
> #21 0x05c7df89418048c1 in ?? ()
> #22 0x00000001003d81e8 in ?? ()
> ---Type <return> to continue, or q <return> to quit---q
>
> The last useful crashdump I've had was before February this year.
> Do others share this experience?
>
> Ian

I haven't had any such problems. I do often get a "broken stack?"  
following the rest of the BT, but they're generally useful anyway, and  
I've never ever seen "Attempt to extract a component of a value that  
is not a structure pointer" before.

Regards,
Thomas