Contents

1. Hardware setup
2. Software setup
3. Compiling the kernel on the development machine
4. Starting the debug session
5. Using KGDB over ethernet interface
6. Useful links and miscellaneous information
   
   

Hardware setup

Software setup

1. Download Linux kernel source : linux-2.6.15.5.tar.bz2
2. Download the Kgdb patch : linux-2.6.15.5-kgdb-2.4.tar.bz2
3. Unzip the kernel sources
       cd ${BASE_DIR}
       tar -jxvf linux-2.6.15.5.tar.bz2
4. Unzip the kgdb patch
       tar -jxvf linux-2.6.15.5-kgdb-2.4.tar.bz2
5. Change the directory as follows:
       cd ${BASE_DIR}/linux-2.6.15.5
6. Apply KGDB patches
       patch -p1 < ${BASE_DIR}/linux-2.6.15.5-kgdb-2.4/core-lite.patch
       ........
       patch -p1 < ${BASE_DIR}/linux-2.6.15.5-kgdb-2.4/i386.patch
   Follow the order mentioned in "series" file while applying the patches

Compiling the kernel on the development machine

1. In the ${BASE_DIR}/linux-2.6.15.5/Makefile, set the EXTRAVERSION = -kgdb
2. make xconfig/oldconfig/menuconfig
       Select the options appropriate for the target machine Hardware.
       Select the options pertaining to kgdb under "Kernel hacking" as shown here
   
3. make bzImage
4. Transfer the built kernel to the Target machine from the Development machine.
   Copy the Kernel image from ${BASE_DIR}/linux-2.6.15.5/arch/i386/boot/bzImage to the target machine as /boot/vmlinuz-2.6.15.5-kgdb
   Copy the Map file from ${BASE_DIR}/linux-2.6.15.5/System.map to the target machine as /boot/System.map-2.6.15.5-kgdb
   Also create links as follows:
       ln -s /boot/vmlinuz-2.6.15.5-kgdb /boot/vmlinuz
       ln -s /boot/System.map-2.6.15.5-kgdb /boot/System.map
5. Edit the /boot/grub/grub.conf file in the target machine to have the kgdb enabled kernel entry.
       title Linux-2.6.15.5-kgdb
       root (hd0,0)
       kernel /boot/vmlinuz-2.6.15.5-kgdb ro root=/dev/hda1 kgdbwait kgdb8250=0,115200
   

Starting the debug session

1. After booting, the target machine will wait for the host development machine to connect, by displaying the message :-
       Waiting for connection from remote gdb...
2. cd ${BASE_DIR}/linux-2.6.15.5
3. For starting a debug session with baud rate of 115200 on /dev/ttyS0 , run the following as "root" user:-
       <root#> gdb ./vmlinux
       GNU gdb (GDB) 7.1-ubuntu
       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 "i486-linux-gnu".
       For bug reporting instructions, please see:
       <http://www.gnu.org/software/gdb/bugs/>...
       (gdb) set remotebaud 115200
       (gdb) target remote /dev/ttyS0
       Remote debugging using /dev/ttyS0
       breakpoint () at kernel/kgdb.c:1212
       1212 atomic_set(&kgdb_setting_breakpoint, 0);
       (gdb)
   
4. For further commands refer http://kgdb.geeksofpune.in/tockdebug.htm

Using KGDB over ethernet interface

1. Add the following kernel parameter to the grub entry:
       kgdboe=@10.0.0.6/,@10.0.0.3/ (that's kgdboe=@LOCAL-IP/,@REMOTE-IP/)
   # Sample grub.cfg which will by default boot the kgdb enabled kernel
       title Linux-2.6.15.5-kgdb(eth)
       root (hd0,0)
       kernel /boot/vmlinuz-2.6.15.5-kgdb ro root=/dev/hda1 kgdboe=@10.0.0.6/,@10.0.0.3/ console=ttyS0,115200
   
2. For starting a debug session, type the following:
       (gdb) ./vmlinux
       (gdb) target remote udp:HOSTNAME:6443
   
3. For further commands refer http://kgdb.geeksofpune.in/tockdebug.htm

Useful links and Miscellaneous information

1. Useful Links :
   http://kgdb.sourceforge.net/
   http://kgdb.geeksofpune.in/
   http://kgdb.geeksofpune.in/downloads/
   
   
2. Active Developers :
         Amit Kale (amitkale@geeksofpune.in),
         Swapnil Pimpale (swapnil@geeksofpune.in)


3. Bug Report: kgdb-bugreport@lists.sourceforge.net