sandbox: Move reading the RAM buffer into a better place

This should not happen in the argument-parsing function. Move it to the
main program.

Add some debugging for reading/writing.

Signed-off-by: Simon Glass <sjg@chromium.org>
diff --git a/arch/sandbox/cpu/start.c b/arch/sandbox/cpu/start.c
index bbd9e77..8582f05 100644
--- a/arch/sandbox/cpu/start.c
+++ b/arch/sandbox/cpu/start.c
@@ -272,17 +272,9 @@
 static int sandbox_cmdline_cb_memory(struct sandbox_state *state,
 				     const char *arg)
 {
-	int err;
-
 	/* For now assume we always want to write it */
 	state->write_ram_buf = true;
 	state->ram_buf_fname = arg;
-
-	err = os_read_ram_buf(arg);
-	if (err) {
-		printf("Failed to read RAM buffer '%s': %d\n", arg, err);
-		return err;
-	}
 	state->ram_buf_read = true;
 
 	return 0;
@@ -512,6 +504,17 @@
 	if (os_parse_args(state, argc, argv))
 		return 1;
 
+	if (state->ram_buf_fname) {
+		ret = os_read_ram_buf(state->ram_buf_fname);
+		if (ret) {
+			printf("Failed to read RAM buffer '%s': %d\n",
+			       state->ram_buf_fname, ret);
+		} else {
+			state->ram_buf_read = true;
+			log_debug("Read RAM buffer from '%s'\n", state->ram_buf_fname);
+		}
+	}
+
 	/* Remove old memory file if required */
 	if (state->ram_buf_rm && state->ram_buf_fname) {
 		os_unlink(state->ram_buf_fname);
diff --git a/arch/sandbox/cpu/state.c b/arch/sandbox/cpu/state.c
index d678349..fcc0028 100644
--- a/arch/sandbox/cpu/state.c
+++ b/arch/sandbox/cpu/state.c
@@ -513,6 +513,7 @@
 			printf("Failed to write RAM buffer\n");
 			return err;
 		}
+		log_debug("Wrote RAM to file '%s'\n", state->ram_buf_fname);
 	}
 
 	if (state->write_state) {