.. include:: /substitutions.rst .. _qemugdb: ===================================== How to debug NuttX using QEMU and GDB ===================================== This guide explains the steps needed to use QEMU and GDB to debug an ARM board (lm3s6965-ek), but it could be modified to work with other board or architecture supported by QEMU. Start configuring and compiling the lm3s6965-ek board with qemu-flat profile. Compiling ========= #. Configure the lm3s6965-ek There is a sample configuration to use lm3s6965-ek on QEMU. Just use ``lm3s6965-ek:qemu-flat`` board profile for this purpose. .. code-block:: console $ cd nuttx $ ./tools/configure.sh lm3s6965-ek:qemu-flat #. Compile .. code-block:: console $ make -j Start QEMU ========== #. You need to start QEMU using the nuttx ELF file just create above: .. code-block:: console $ qemu-system-arm -M lm3s6965evb -device loader,file=nuttx -serial mon:stdio -nographic -s Timer with period zero, disabling ABCDF telnetd [4:100] NuttShell (NSH) NuttX-12.0.0 nsh> Start GDB to connect to QEMU ============================ These steps show how to connect GDB to QEMU running NuttX: .. code-block:: console $ gdb-multiarch -ix tools/nuttx-gdbinit nuttx (gdb) target extended-remote localhost:1234 Remote debugging using localhost:1234 0x000012ee in up_mdelay (milliseconds=milliseconds@entry=250) at common/arm_mdelay.c:51 51 for (j = 0; j < CONFIG_BOARD_LOOPSPERMSEC; j++) (gdb) #. From (gdb) prompt you can run commands to inpect NuttX: .. code-block:: console (gdb) info_nxthreads target examined _target_arch.name=armv7 $_target_has_fpu : 1 $_target_has_smp : 0 saved current_tcb (pid=0) * 0 Thread 0x20001538 (Name: Idle Task, State: Running, Priority: 0, Stack: 464/1000) PC: 0x12fc in up_mdelay() saved current_tcb (pid=0) 1 Thread 0x20005060 (Name: hpwork, State: Waiting,Semaphore, Priority: 224, Stack: 320/1992) PC: 0x47dd in work_thread() saved current_tcb (pid=0) 2 Thread 0x20005c30 (Name: nsh_main, State: Waiting,Semaphore, Priority: 100, Stack: 1016/2000) PC: 0x1 in _vectors() saved current_tcb (pid=0) 3 Thread 0x20006b40 (Name: NTP daemon, State: Waiting,Signal, Priority: 100, Stack: 864/1952) PC: 0x0 in _vectors() saved current_tcb (pid=0) 4 Thread 0x20008540 (Name: telnetd, State: Waiting,Semaphore, Priority: 100, Stack: 616/2008) PC: 0x20008fd4 in No() saved current_tcb (pid=0) saved current_tcb (pid=0) saved current_tcb (pid=0) saved current_tcb (pid=0) (gdb) As you can see QEMU and GDB are powerful tools to debug NuttX without using external board or expensive debugging hardware.