svn commit: r222537 - in head/sys: kern sys

[Garrett Cooper]

On Tue, May 31, 2011 at 2:14 PM, Garrett Cooper <yanegomi at gmail.com> wrote:
> On Tue, May 31, 2011 at 2:00 PM,  <mdf at freebsd.org> wrote:
>> On Tue, May 31, 2011 at 10:29 AM, Kenneth D. Merry <ken at freebsd.org> wrote:
>>> Author: ken
>>> Date: Tue May 31 17:29:58 2011
>>> New Revision: 222537
>>> URL: http://svn.freebsd.org/changeset/base/222537
>>>
>>> Log:
>>>  Fix apparent garbage in the message buffer.
>>>
>>>  While we have had a fix in place (options PRINTF_BUFR_SIZE=128) to fix
>>>  scrambled console output, the message buffer and syslog were still getting
>>>  log messages one character at a time.  While all of the characters still
>>>  made it into the log (courtesy of atomic operations), they were often
>>>  interleaved when there were multiple threads writing to the buffer at the
>>>  same time.
>>
>> This seems to panic my box with "lock "msgbuf" 0xfffffe0127ffffe0
>> already initialized".
>>
>> Unfortunately, though I booted with a fresh CURRENT this morning
>> successfully, both /boot/kernel and /boot/kernel.old give this panic.
>> To add insult to injury, when the kernel drops into the debugger, my
>> keyboard input no longer works so I can't get a stack, etc.
>>
>> So:
>>
>> 1) Is there anything else I can do to help debug this?
>
> 1. sysctl debug.debugger_on_panic=1 ?

Sorry.. I meant 'debug.debugger_on_panic=0'.

>> 2) how can I resurrect this box without a reinstall?
>
> 2. Best way is to probably to use the bsdinstall CD, use the LiveCD
> mode, setup the system as usual (mount /, mount devfs, chroot, mount
> -a), rewind to an earlier version of svn (shouldn't be too hard if you
> run /etc/rc.d/network restart from inside the chroot), rebuild the
> kernel (and potentially world), and install the kernel to the chroot,
> then exit and reboot (this is a method I picked up from installing
> Gentoo Linux multiple times, but it should work for FreeBSD as well).
>
> This is part of the reason why I'm an avid using of make installkernel
> INSTKERNNAME=$KERNCONF.$SVN_REVISION , symlink /boot/kernel to the
> latest one I want to boot, and I only go through every once in a blue
> moon to reap the kernels I don't need anymore -- I don't know until
> after a few weeks soak on my workstation whether or not a regression
> is present in the kernel.
>
>> I will try to repro on a virtual machine so I have a snapshot to come back to.