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