build: pc is set to _start after program load

Signed-off-by: Huaqi Fang <578567190@qq.com>

Build/Makefile.conf

@@ -62,9 +62,19 @@ GDB_UPLOAD_ARGS ?= --batch
 GDB_UPLOAD_CMDS += -ex "thread apply all monitor reset halt"
 # $$pc is for $pc in gdb, but need to do this in makefile
 # in command extra '\' is required
-GDB_UPLOAD_CMDS += -ex "thread apply all set \$$pc=_start"
+# please make sure the _start label is provided in your startup code
+# and is the entry of the startup of cpu
+GDB_UPLOAD_CMDS += -ex "thread apply all info reg pc"
 GDB_UPLOAD_CMDS += -ex "thread 1"
 GDB_UPLOAD_CMDS += -ex "load"
+# make sure pc is set to _start after load
+# when load program to flash, the cpu will do reset init
+# before flash erase and do reset halt after flash write end
+# so we need to manually set pc to _start
+# see https://openocd.org/doc/html/CPU-Configuration.html#Target-Events
+GDB_UPLOAD_CMDS += -ex "thread apply all set \$$pc=_start"
+GDB_UPLOAD_CMDS += -ex "thread apply all info reg pc"
+GDB_UPLOAD_CMDS += -ex "thread 1"
 GDB_UPLOAD_CMDS += -ex "monitor resume"
 GDB_UPLOAD_CMDS += -ex "quit"