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Operating Systems Linux Red Hat Gdb error while debugging core file Post 302891662 by sanzee007 on Friday 7th of March 2014 05:54:40 AM
Old 03-07-2014
RedHat Gdb error while debugging core file

Hi,
I am trying to analyze one core file on my RHEL 6.5, but I am getting below error related to the core file. So I am not getting any stack trace about the crash.
Code:
#  gdb MyDebugBin /var/core/MyDebugBin.27005
GNU gdb (GDB) Red Hat Enterprise Linux (7.2-60.el6_4.1)
Copyright (C) 2010 Free Software Foundation, Inc.
License GPLv3+: GNU GPL version 3 or later <http://gnu.org/licenses/gpl.html>
This is free software: you are free to change and redistribute it.
There is NO WARRANTY, to the extent permitted by law.  Type "show copying"
and "show warranty" for details.
This GDB was configured as "x86_64-redhat-linux-gnu".
For bug reporting instructions, please see:
<http://www.gnu.org/software/gdb/bugs/>...
Reading symbols from MyDebugBin...done.
BFD: Warning: MyDebugBin.27005 is truncated: expected core file size >= 47775744, found: 2387968.
[New Thread 27005]
Cannot access memory at address 0x4baca8e8
Cannot access memory at address 0x4baca8e8
Cannot access memory at address 0x4baca8e8
Reading symbols from /lib/ld-linux.so.2...(no debugging symbols found)...done.
Loaded symbols for /lib/ld-linux.so.2
Failed to read a valid object file image from memory.
Core was generated by `/path_to_my_debug_bin/MyDebugBin :12 -auth /var/run/gdm/auth-for-gdm-kUgSIC/database'.
Program terminated with signal 11, Segmentation fault.
#0  0x4bb48506 in ?? ()
Missing separate debuginfos, use: debuginfo-install glibc-2.12-1.132.el6.i686
(gdb) bt
#0  0x4bb48506 in ?? ()
Cannot access memory at address 0xffe51198
(gdb) quit

Why gdb is complaining about the core size? There is enough space left for core files with ulimit unlimited set for core file.

How to fix this kind of error or problem related to gdb? Is it a known bug in gdb on higher version of linux kernel?

thanks,
 

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savecore(8)						      System Manager's Manual						       savecore(8)

Name
       savecore - save a core dump of the operating system

Syntax
       /etc/savecore [ options ] dirname [ system ] [ corename ]

Description
       The  command  is  meant	to  be called near the end of the file.  The command saves the core dump of the system (assuming one was made) and
       writes a reboot message in the shutdown log.

       The command checks the core dump to be certain it corresponds with the current running ULTRIX.  If it does, it saves the core image in  the
       file  dirname/vmcore.n and saves the namelist in the file dirname/vmunix.n.  The trailing .n in the pathnames is replaced by a number which
       increments each time is run in that directory.

       After saving the core and namelist images, will save the error logger buffer into a predetermined file.	The error logger  buffer  contains
       information about why the crash occurred.  After completes, the daemon will extract the error logger file and translate its contents into a
       form familiar to the program.

       Before writes out a core image, it reads a number from the file dirname/minfree.  If there are fewer free blocks  on  the  filesystem  that
       contains  dirname  than the number obtained from the file, a core dump is not done.  If the file does not exist, savecore always writes out
       the core file (assuming that a core dump was taken).

       The command also writes a reboot message in the shut down log.  If the system crashed as a result of a panic, also records the panic string
       in the shut down log.

       For  partial  crash  dumps,  creates  a	sparse	core image file in dirname/vmcore.n.  If this sparse core image file is copied or moved to
       another location, the file expands to its true size which can take too much file system space.  Hence, to copy or move  sparse  core  image
       files, you must use the command. The command has a conversion option to create sparse output files.

Options
       -c   Clears  the core dump.  This option is useful when the core dump is corrupted in a way that will not allow to save it safely.  Use the
	    option with caution, because once it clears the core dump, the core dump cannot be retrieved.

       -d dumpdev dumplo
	    Specifies the dump device and the dump offset when running on a system image other than the currently running system image.  The  pro-
	    gram  assumes  that  the running system image is and it reads the dump device and dump device offset are different in the system image
	    that crashed, the option provides the correct dump device and dump device offset.

       -e   Saves only the error logger buffer into a file.  If used, core or namelist images are not saved.

       -f corename
	    Takes the i corefile name as the file from which to extract the the crash dump data instead of the default dump device.   This  option
	    is used only for diskless workstations.

       If  the	core  dump was from a system other than /vmunix, the name of that system must be supplied as system.  The program assumes that the
       running image is

       After successful completion, the core dump is cleared.  Also, a message is written in the file which tells whether the  dump  succeeded	or
       failed.

Files
       Shut down log

       Current running ULTRIX system

See Also
       dd(1), uerf(8)

																       savecore(8)
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