Date: Fri, 27 Jan 2012 15:01:29 +0100 From: Marius Strobl <marius@alchemy.franken.de> To: Denny Schierz <linuxmail@4lin.net> Cc: freebsd-sparc64@freebsd.org Subject: Re: Howto debug Kernel problems ? (jail -r -> freeze) Message-ID: <20120127140129.GA32328@alchemy.franken.de> In-Reply-To: <6F47ED26-0604-46C9-BA6F-0802D917D4AE@4lin.net> References: <5C638638-3D1A-417E-A574-9BCE51E08C59@4lin.net> <20120124202111.GB7731@alchemy.franken.de> <431CCA8C-2E5E-43BC-89EE-7F06CF8E8E8D@4lin.net> <20120125150054.GA15762@alchemy.franken.de> <926170B2-9DF2-4DCC-9643-E66E6504B185@4lin.net> <4F202586.5010808@xs4all.nl> <6F47ED26-0604-46C9-BA6F-0802D917D4AE@4lin.net>
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On Thu, Jan 26, 2012 at 12:55:02PM +0100, Denny Schierz wrote:
> hi,
>
> Am 25.01.2012 um 16:53 schrieb Michiel Boland:
>
> > sysctl debug.kdb.alt_break_to_debugger=1
>
> great :-), it works (until ... )
>
> I did the test again:
>
> /etc/rc.d/jail onestart
> /etc/rc.d/jail/onestop
>
> jls ...
>
> jail -r 1
>
> The command hangs, the server doesn't accept ssh connections anymore, but ping works. But only until I make something like "telnet localhost 22" to check, if SSH accept from localhost .. .... FREEZE ....
>
> back to ALOM, send break ... connect ... nothing. -> Reset
>
>From your email it's once again not clear whether the alternate
break sequence works or not when the the machine hangs. If it
doesn't the only thing I currently can think of is to resort to
printf(9)-debugging starting at sys_jail_remove() in kern_jail.c
in order to determine where the hang occurs. This somewhat smells
like the kernel trying to directly use and userland address and
not going through copy{in,out}(9), which would match both the
symptoms of a hang and it just working anyway on x86. On a
quick glance at kern_jail.c I can't spot an obvious issue. From
your previous emails and the mailing list reference you gave it's
also not clear whether you are using some kernel patch which might
introduce such a bug though.
Marius
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