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+                        A Simple Guide to Configure KGDB
+
+                        Sonic Zhang <sonic.zhang@analog.com>
+                                Aug. 24th 2006
+
+
+This KGDB patch enables the kernel developer to do source level debugging on
+the kernel for the Blackfin architecture.  The debugging works over either the
+ethernet interface or one of the uarts.  Both software breakpoints and
+hardware breakpoints are supported in this version.
+http://docs.blackfin.uclinux.org/doku.php?id=kgdb
+
+
+2 known issues:
+1. This bug:
+       http://blackfin.uclinux.org/tracker/index.php?func=detail&aid=544&group_id=18&atid=145
+   The GDB client for Blackfin uClinux causes incorrect values of local
+   variables to be displayed when the user breaks the running of kernel in GDB.
+2. Because of a hardware bug in Blackfin 533 v1.0.3:
+       05000067 - Watchpoints (Hardware Breakpoints) are not supported
+   Hardware breakpoints cannot be set properly.
+
+
+Debug over Ethernet:
+ 
+1. Compile and install the cross platform version of gdb for blackfin, which
+   can be found at $(BINROOT)/bfin-elf-gdb.
+
+2. Apply this patch to the 2.6.x kernel.  Select the menuconfig option under
+   "Kernel hacking" -> "Kernel debugging" -> "KGDB: kernel debug with remote gdb".
+   With this selected, option "Full Symbolic/Source Debugging support" and 
+   "Compile the kernel with frame pointers" are also selected.
+
+3. Select option "KGDB: connect over (Ethernet)".  Add "kgdboe=@target-IP/,@host-IP/" to
+   the option "Compiled-in Kernel Boot Parameter" under "Kernel hacking".
+
+4. Connect minicom to the serial port and boot the kernel image.
+
+5. Configure the IP "/> ifconfig eth0 target-IP"
+
+6. Start GDB client "bfin-elf-gdb vmlinux".
+
+7. Connect to the target "(gdb) target remote udp:target-IP:6443".
+
+8. Set software breakpoint "(gdb) break sys_open".
+
+9. Continue "(gdb) c".
+
+10. Run ls in the target console "/> ls".
+
+11. Breakpoint hits. "Breakpoint 1: sys_open(..."
+
+12. Display local variables and function paramters.
+    (*) This operation gives wrong results, see known issue 1.
+
+13. Single stepping "(gdb) si".
+
+14. Remove breakpoint 1. "(gdb) del 1"
+
+15. Set hardware breakpoint "(gdb) hbreak sys_open".
+
+16. Continue "(gdb) c".
+
+17. Run ls in the target console "/> ls".
+
+18. Hardware breakpoint hits. "Breakpoint 1: sys_open(...".
+    (*) This hardware breakpoint will not be hit, see known issue 2.
+
+19. Continue "(gdb) c".
+
+20. Interrupt the target in GDB "Ctrl+C".
+
+21. Detach from the target "(gdb) detach".
+
+22. Exit GDB "(gdb) quit".
+
+
+Debug over the UART:
+
+1. Compile and install the cross platform version of gdb for blackfin, which
+   can be found at $(BINROOT)/bfin-elf-gdb.
+
+2. Apply this patch to the 2.6.x kernel.  Select the menuconfig option under
+   "Kernel hacking" -> "Kernel debugging" -> "KGDB: kernel debug with remote gdb".
+   With this selected, option "Full Symbolic/Source Debugging support" and 
+   "Compile the kernel with frame pointers" are also selected.
+
+3. Select option "KGDB: connect over (UART)".  Set "KGDB: UART port number" to be
+   a different one from the console.  Don't forget to change the mode of
+   blackfin serial driver to PIO.  Otherwise kgdb works incorrectly on UART.
+ 
+4. If you want connect to kgdb when the kernel boots, enable
+   "KGDB: Wait for gdb connection early" 
+
+5. Compile kernel.
+
+6. Connect minicom to the serial port of the console and boot the kernel image.
+
+7. Start GDB client "bfin-elf-gdb vmlinux".
+
+8. Set the baud rate in GDB "(gdb) set remotebaud 57600".
+
+9. Connect to the target on the second serial port "(gdb) target remote /dev/ttyS1".
+
+10. Set software breakpoint "(gdb) break sys_open".
+
+11. Continue "(gdb) c". 
+
+12. Run ls in the target console "/> ls". 
+
+13. A breakpoint is hit. "Breakpoint 1: sys_open(..."
+
+14. All other operations are the same as that in KGDB over Ethernet. 
+
+
+Debug over the same UART as console:
+
+1. Compile and install the cross platform version of gdb for blackfin, which
+   can be found at $(BINROOT)/bfin-elf-gdb.
+
+2. Apply this patch to the 2.6.x kernel.  Select the menuconfig option under
+   "Kernel hacking" -> "Kernel debugging" -> "KGDB: kernel debug with remote gdb".
+   With this selected, option "Full Symbolic/Source Debugging support" and 
+   "Compile the kernel with frame pointers" are also selected.
+
+3. Select option "KGDB: connect over UART".  Set "KGDB: UART port number" to console.
+   Don't forget to change the mode of blackfin serial driver to PIO.
+   Otherwise kgdb works incorrectly on UART.
+ 
+4. If you want connect to kgdb when the kernel boots, enable
+   "KGDB: Wait for gdb connection early" 
+
+5. Connect minicom to the serial port and boot the kernel image. 
+
+6. (Optional) Ask target to wait for gdb connection by entering Ctrl+A. In minicom, you should enter Ctrl+A+A.
+
+7. Start GDB client "bfin-elf-gdb vmlinux".
+
+8. Set the baud rate in GDB "(gdb) set remotebaud 57600".
+
+9. Connect to the target "(gdb) target remote /dev/ttyS0".
+
+10. Set software breakpoint "(gdb) break sys_open".
+
+11. Continue "(gdb) c". Then enter Ctrl+C twice to stop GDB connection.
+
+12. Run ls in the target console "/> ls". Dummy string can be seen on the console.
+
+13. Then connect the gdb to target again. "(gdb) target remote /dev/ttyS0".
+    Now you will find a breakpoint is hit. "Breakpoint 1: sys_open(..."
+
+14. All other operations are the same as that in KGDB over Ethernet.  The only
+    difference is that after continue command in GDB, please stop GDB
+    connection by 2 "Ctrl+C"s and connect again after breakpoints are hit or
+    Ctrl+A is entered.