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Date:      Fri, 29 Jan 2010 06:33:14 -0800
From:      Jeremy Chadwick <freebsd@jdc.parodius.com>
To:        freebsd-stable@freebsd.org
Subject:   Re: 8.0-RELEASE -> -STABLE and size of /
Message-ID:  <20100129143314.GA46085@icarus.home.lan>
In-Reply-To: <4B62EFD7.2010800@icyb.net.ua>
References:  <20100122162155.GG3917@e-Gitt.NET> <201001232244.03752.doconnor@gsoft.com.au> <20100129104624.GA13472@ei.bzerk.org> <201001292230.01867.doconnor@gsoft.com.au> <20100129134030.GA44869@icarus.home.lan> <4B62EFD7.2010800@icyb.net.ua>

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On Fri, Jan 29, 2010 at 04:25:27PM +0200, Andriy Gapon wrote:
> on 29/01/2010 15:40 Jeremy Chadwick said the following:
> > On Fri, Jan 29, 2010 at 10:29:51PM +1030, Daniel O'Connor wrote:
> >> On Fri, 29 Jan 2010, Ruben de Groot wrote:
> >>>> I don't think you need them unless remote debugging and in that
> >>>> case you are multiuser (I would have thought anyway).
> >>>>
> >>>> If they went into /usr then /boot could remain slim.
> >>> But what if you have /usr on a gmirror, glabel, zfs filesystem or any
> >>> other device that is not compiled in your kernel? Sure you can build
> >>> a custom kernel, but I would expect a lot of questions, frustrations
> >>> and footshooting from such a change.
> >>>
> >>> I think increasing / (again) would be the least painfull.
> >> You don't need debug symbols to boot a kernel, you only need them when 
> >> debugging.
> > 
> > Somewhat related: can someone explain why debugging a crash dump of a
> > kernel which contains "makeoptions DEBUG=-g" requires and relies on
> > stuff in /usr/obj?
> 
> So do remove or not install *.symbols files?
> That would explain it.
> I keep those files  and my debugging doesn't depend on /usr/obj.
> 
> > Meaning: if I build kernel/world, install kernel/world, and then rm -fr
> > /usr/obj/*, I won't be able to reliably debug a crash dump after the
> > system restarts.  I believe I can get a stack trace, but there's nothing
> > else that can be ascertained (bt full is basically worthless).
> > 
> > I've seen kernel crash dumps from people here on the list[1] which
> > contain way more detail than any of mine do[2].
> > 
> > Off-topic: I've noticed that /usr/obj is created as part of the OS
> > installation with perms 0755.  I've always thought there might be
> > security implications by that, so usually end up setting it to 0700 or
> > possibly 0750 (still root:wheel).
> > 
> > [1]: http://lists.freebsd.org/pipermail/freebsd-stable/2010-January/054269.html
> > [2]: http://lists.freebsd.org/pipermail/freebsd-stable/2009-October/052256.html

The *.symbols files I have for the kernel are installed in /boot/kernel.
I'm referring to "stuff" in /usr/obj which appears to be required to
debug a crash (vmcore).  What I'm describing is even mentioned in the
FreeBSD Developers Handbook:

http://www.freebsd.org/doc/en/books/developers-handbook/kerneldebug-gdb.html

Note the first two steps:

 1:# cd /usr/obj/usr/src/sys/KERNCONF
 2:# kgdb kernel.debug /var/crash/vmcore.0

-- 
| Jeremy Chadwick                                   jdc@parodius.com |
| Parodius Networking                       http://www.parodius.com/ |
| UNIX Systems Administrator                  Mountain View, CA, USA |
| Making life hard for others since 1977.              PGP: 4BD6C0CB |




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