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diff --git a/Documentation/blackfin/kgdb.txt b/Documentation/blackfin/kgdb.txt new file mode 100644 index 00000000000..84f6a484ae9 --- /dev/null +++ b/Documentation/blackfin/kgdb.txt @@ -0,0 +1,155 @@ + 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. |