runners: stlink_gdbserver: add --no-load argument to skip flash

Add new argument "--no-load" for debug sessions ("west debug" only) which
skips flashing binary before debugging. This flag functions exactly like
its identically-named counterpart in the OpenOCD runner: when present, the
"load" command is not added to the GDB client's command line. This allows
starting a debug session from reset but without flashing a binary, which is
useful to avoid unnecessary write cycles. Functionally, this could already
be achieved by running "west debugserver" in a terminal and "west attach"
in another, but using this flag is a more convenient method.

Signed-off-by: Mathieu Choplain <[email protected]>

Author: mathieuchopstm

scripts/west_commands/runners/stlink_gdbserver.py

@@ -110,10 +110,23 @@ def do_add_parser(cls, parser: argparse.ArgumentParser):
             help="Port number for GDB client",
         )
 
+        # Additional arguments
+        parser.add_argument(
+            "--no-load",
+            action='store_true',
+            help="Don't flash binary before debug (no GDB 'load' command)",
+        )
+
     @classmethod
     def do_create(cls, cfg: RunnerConfig, args: argparse.Namespace) -> "STLinkGDBServerRunner":
         return STLinkGDBServerRunner(
-            cfg, args.swd, args.apid, args.dev_id, args.port_number, args.extload
+            cfg,
+            args.swd,
+            args.apid,
+            args.dev_id,
+            args.port_number,
+            args.extload,
+            args.no_load,
         )
 
     def __init__(
@@ -124,6 +137,7 @@ def __init__(
         stlink_serial: str | None,
         gdb_port: int,
         external_loader: str | None,
+        no_load: bool,
     ):
         super().__init__(cfg)
         self.ensure_output('elf')
@@ -133,6 +147,7 @@ def __init__(
         self._stlink_serial = stlink_serial
         self._ap_id = ap_id
         self._external_loader = external_loader
+        self._no_load = no_load
 
     def do_run(self, command: str, **kwargs):
         if command in ["attach", "debug", "debugserver"]:
@@ -165,7 +180,8 @@ def do_attach_debug_debugserver(self, command: str):
             gdbserver_cmd += ["--attach"]
         else:  # debug/debugserver
             gdbserver_cmd += ["--initialize-reset"]
-            gdb_args += ["-ex", f"load {elf_path}"]
+            if not self._no_load:
+                gdb_args += ["-ex", f"load {elf_path}"]
 
         if self._stlink_serial:
             gdbserver_cmd += ["--serial-number", self._stlink_serial]