While debugging a single processor core
using GDB on the command line is straightforward, some extra steps are required to debug
other cores.
- Start the hardware server on the machine where the board is connected. For every processor architecture, a GDB server is started on the ports described above.
- Start GDB from a terminal (for example, $XILINX_VITS/gnu/aarch64/lin/aarch64-none/bin/aarch64-none-elf-gdb to debug A64 applications).
- Connect to the GDB server using the
target extendedcommand (for example,tar ext :3001). Thetarget extendedcommand is required to debug multiple cores. - To see a list of available targets, run the
monitor pscommand. The hardware server extends the monitor command to support listing of available targets. - To debug the second core, add it as an inferior and attach to it.
- To debug other cores, detach the previous core, and repeat the previous
step. See the following code snippet for a full example of the steps.Note: Processor cores must be in a stopped or running state before they can be used with GDB. Remember to clear resets (through XSDB, for example) before using GDB.
# connect to gdbserver (gdb) tar ext xhdbfarmrki7:3001 Remote debugging using xhdbfarmrki7:3001 warning: No executable has been specified and target does not support determining executable automatically. Try using the "file" command. 0x00000000ffff0000 in ?? () # view available targets (gdb) mon ps 1: Cortex-A53 #0 (Reset Catch) 2: Cortex-A53 #1 (Reset Catch) 3: Cortex-A53 #2 (Reset Catch) 4: Cortex-A53 #3 (Reset Catch) # add other cores (2, 3, and 4) as inferiors (gdb) add-infe [New inferior 2] Added inferior 2 (gdb) add-infe [New inferior 3] Added inferior 3 (gdb) add-infe [New inferior 4] Added inferior 4 # switch to inferior 2 (gdb) infe 2 [Switching to inferior 2 [<null>] (<noexec>)] # attach to 2nd core (gdb) attach 2 Attaching to process 2 warning: No executable has been specified and target does not support determining executable automatically. Try using the "file" command. 0x00000000ffff0000 in ?? () # detach before connecting to other cores (gdb) detach Detaching from program: , process 2 [Inferior 2 (process 2) detached] # 3rd core (gdb) infe 3 [Switching to inferior 3 [<null>] (<noexec>)] (gdb) attach 3 Attaching to process 3 warning: No executable has been specified and target does not support determining executable automatically. Try using the "file" command. Thread 2.1 stopped. 0x0000000000000000 in ?? () (gdb) detach Detaching from program: , process 3 [Inferior 2 (process 3) detached] # 4th core (gdb) infe 4 [Switching to inferior 3 [<null>] (<noexec>)] (gdb) attach 4 Attaching to process 4 warning: No executable has been specified and target does not support determining executable automatically. Try using the "file" command. Thread 2.1 stopped. 0x0000000000000110 in ?? ()