--- nono/host/hostcom.cpp	2026/04/29 17:05:47	1.1.1.8
+++ nono/host/hostcom.cpp	2026/04/29 17:05:56	1.1.1.10
@@ -117,7 +117,7 @@ HostCOMDevice::SetLogLevel(int loglevel_
 {
 	inherited::SetLogLevel(loglevel_);
 
-	std::lock_guard<std::mutex> guard(driverlock);
+	RWLockGuard_Read guard(driverlock);
 	if ((bool)driver) {
 		driver->SetLogLevel(loglevel_);
 	}
@@ -131,18 +131,6 @@ HostCOMDevice::Create2()
 		return false;
 	}
 
-	// hostcom*-fallback は使わなくなったので、
-	// 初期値から変更されていれば警告だけ出す。
-	std::string key = GetConfigKey();
-	if (key != "debugger") {
-		const std::string fallback_key = key + "-fallback";
-		const ConfigItem& fallback_item = gConfig->Find(fallback_key);
-		if (fallback_item.GetFrom() != ConfigItem::FromInitial) {
-			warnx("Warning: option '%s' has been obsoleted.",
-				fallback_key.c_str());
-		}
-	}
-
 	if (SelectDriver(true) == false) {
 		return false;
 	}
@@ -158,7 +146,7 @@ HostCOMDevice::Create2()
 bool
 HostCOMDevice::SelectDriver(bool startup)
 {
-	std::lock_guard<std::mutex> guard(driverlock);
+	RWLockGuard_Write guard(driverlock);
 
 	driver.reset();
 	errmsg.clear();
@@ -210,7 +198,7 @@ HostCOMDevice::SelectDriver(bool startup
 		} else {
 			// UI に通知してフォールバック。
 			int n = (key == "debugger") ? -1 : GetId() - OBJ_HOSTCOM0;
-			UIMessage::Post(UIMessage::HOSTCOM_FAILED, n);
+			gMainApp.GetUIMessage()->Post(UIMessage::HOSTCOM_FAILED, n);
 
 			CreateNone();
 		}
@@ -310,7 +298,7 @@ HostCOMDevice::Dispatch(int udata)
 {
 	// driver の Dispatch は処理し終わったら DONE を返す
 	{
-		std::lock_guard<std::mutex> guard(driverlock);
+		RWLockGuard_Read guard(driverlock);
 		udata = driver->Dispatch(udata);
 	}
 
@@ -385,7 +373,7 @@ HostCOMDevice::Rx()
 int
 HostCOMDevice::Read()
 {
-	std::lock_guard<std::mutex> guard(driverlock);
+	RWLockGuard_Read guard(driverlock);
 	assert((bool)driver);
 
 	int data = driver->Read();
@@ -411,7 +399,7 @@ HostCOMDevice::Write()
 {
 	uint8 data;
 
-	std::lock_guard<std::mutex> guard(driverlock);
+	RWLockGuard_Read guard(driverlock);
 	assert(driver);
 
 	// 送信キューを全部吐き出す
@@ -422,10 +410,10 @@ HostCOMDevice::Write()
 }
 
 // ドライバ名を返す
-const std::string
+const std::string&
 HostCOMDevice::GetDriverName()
 {
-	std::lock_guard<std::mutex> guard(driverlock);
+	RWLockGuard_Read guard(driverlock);
 	assert((bool)driver);
 	return driver->GetDriverName();
 }
@@ -438,8 +426,9 @@ HostCOMDevice::MonitorUpdate(Monitor *,
 
 	screen.Print(0, 0, "Device(Port)  : %s", GetPortName().c_str());
 	{
-		std::lock_guard<std::mutex> guard(driverlock);
-		screen.Print(0, 1, "HostCOM Driver: %s", driver->GetDriverName());
+		RWLockGuard_Read gurad(driverlock);
+		screen.Print(0, 1, "HostCOM Driver: %s",
+			driver->GetDriverName().c_str());
 		// 次の1行はドライバ依存情報
 		driver->MonitorUpdateMD(screen, 2);
 	}