Date: Wed, 24 Feb 2010 20:00:35 +0100 From: Alexey Shuvaev <shuvaev@physik.uni-wuerzburg.de> To: Peter Steele <psteele@maxiscale.com> Cc: "freebsd-hackers@freebsd.org" <freebsd-hackers@freebsd.org> Subject: Re: ntpd hangs under FBSD 8 Message-ID: <20100224190035.GA5026@wep4035.physik.uni-wuerzburg.de> In-Reply-To: <7B9397B189EB6E46A5EE7B4C8A4BB7CB39E95389@MBX03.exg5.exghost.com> References: <7B9397B189EB6E46A5EE7B4C8A4BB7CB385D5C73@MBX03.exg5.exghost.com> <20100220113349.GA22800@kiwi.sharlinx.com> <7B9397B189EB6E46A5EE7B4C8A4BB7CB385D60B7@MBX03.exg5.exghost.com> <bc2d971002220751i256f2329g3f29efdc763bca97@mail.gmail.com> <7B9397B189EB6E46A5EE7B4C8A4BB7CB385D60DD@MBX03.exg5.exghost.com> <7B9397B189EB6E46A5EE7B4C8A4BB7CB39E95389@MBX03.exg5.exghost.com>
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On Wed, Feb 24, 2010 at 12:17:50PM -0600, Peter Steele wrote:
> >You're going to need a debug version of libc, too.
> >gdb won't be able to find a backtrace out of a libc function without it.
>
> What's the proper way to build a debug version of libc and the other
> libraries? I tried this:
>
> export CFLAGS="-O0"
> make buildworld
> make installworld DESTDIR=/mydir
>
> and then copied libc.so.7 from /mydir/lib to the /lib dir on
> my target system. I also replaced the ntpd binary with the debug version.
> I can see that -O0 is being used in the various "cc" commands that are
> generated, but libc still doesn't seem to be built properly.
> When I attach to a hung ntpd process, I get this:
>
> # gdb /usr/sbin/ntpd -p 2113
> GNU gdb 6.1.1 [FreeBSD]
> ...
> Attaching to program: /usr/sbin/ntpd, process 2113
> Reading symbols from /lib/libm.so.5...(no debugging symbols found)...done.
> ...
> Reading symbols from /lib/libc.so.7...(no debugging symbols found)...done.
> Loaded symbols for /lib/libc.so.7
> Reading symbols from /lib/libthr.so.3...(no debugging symbols found)...done.
> ...
> [Switching to Thread 8012041c0 (LWP 100283)]
> 0x0000000800dbeddc in select () from /lib/libc.so.7
> (gdb) bt
> #0 0x0000000800dbeddc in select () from /lib/libc.so.7
> #1 0x00000000004335de in ntpdmain ()
> #2 0x000000000043310b in main ()
>
> So I'm getting some symbols from ntpd but I still can't see into select().
>
I think not.
> It hangs in there forever so that's where I need to drill down further.
> How do I get libc built with full debug symbols?
>
I haven't tried it by myself but think here is the way to go: put the
following to /etc/make.conf and recompile needed libraries / ports.
WITH_DEBUG=yes
DEBUG_FLAGS=-g
This should do the trick for both base and ports.
>
> [snip]
>
> If anyone has any clues at all as to what is causing this issue,
> I'd appreciate the feedback. Here's the code that reproduces this behavior.
>
> #! /usr/bin/env python
> import os
> import threading
>
> class RunProc(threading.Thread):
> def __init__(self, cmd):
> threading.Thread.__init__(self)
> self.cmd = cmd
>
> def run(self):
> os.system(self.cmd)
>
> def main():
> RunProc("/usr/sbin/ntpd -g -q").start()
>
> if __name__ == "__main__":
> main()
>
Mmm... Do other daemons (sshd, lpd, ...) also fail when started
through this script? Normal commands (ls, ps) seem not affected.
0.02$,
Alexey.
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