bootstrap: create a channel to receive/reply to simple string messages

sys/bootstrap/main.c

@@ -87,13 +87,40 @@ int main(
 		.p_resolver_arg = &bsp,
 	};
 
+	kern_handle_t channel;
+	channel_create(0, 0, &channel);
+
 	launch_ctx_init(&launch);
 	launch.ctx_resolve_library = resolve_dependency;
 
 	enum launch_status status
 		= launch_ctx_execute(&launch, &params, LAUNCH_F_NONE, &result);
+	kern_logf("launch result: %d", status);
 
-	kern_tracef("launch result: %d", status);
+#if 1
+	char msg_buf[512];
+	struct iovec vec = {
+		.io_base = (virt_addr_t)msg_buf,
+		.io_len = sizeof msg_buf,
+	};
+	struct msg msg = {.msg_data = &vec, .msg_data_count = 1};
+
+	while (1) {
+		msgid_t id = 0;
+		kern_status_t kstatus = msg_recv(channel, 0, &id, &msg);
+		if (kstatus != KERN_OK) {
+			kern_logf("msg_recv failed %d", kstatus);
+			break;
+		}
+
+		kern_logf("received message %zx: %s", id, msg_buf);
+
+		size_t len = snprintf(msg_buf, sizeof msg_buf, "Goodbye!");
+		vec.io_len = len + 1;
+
+		msg_reply(channel, 0, id, &msg);
+	}
+#endif
 
 	return 102;
 }