hw/usb: Do not build USB subsystem if not required

If the Kconfig 'USB' value is not selected, it is pointless to
build the USB core components. Add a stub for the HMP commands
and usbdevice_create() which is called by usb_device_add in
softmmu/vl.c.

Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-Id: <20210424224110.3442424-3-f4bug@amsat.org>
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>

1 files changed, 25 insertions, 0 deletions

diff --git a/stubs/usb-dev-stub.c b/stubs/usb-dev-stub.c
new file mode 100644
index 0000000000..b1adeeb454
--- /dev/null
+++ b/stubs/usb-dev-stub.c
@@ -0,0 +1,25 @@
+/*
+ * QEMU USB device emulation stubs
+ *
+ * Copyright (C) 2021 Philippe Mathieu-Daudé <f4bug@amsat.org>
+ *
+ * SPDX-License-Identifier: GPL-2.0-or-later
+ */
+
+#include "qemu/osdep.h"
+#include "qemu/error-report.h"
+#include "sysemu/sysemu.h"
+#include "monitor/monitor.h"
+#include "hw/usb.h"
+
+USBDevice *usbdevice_create(const char *driver)
+{
+    error_report("Support for USB devices not built-in");
+
+    return NULL;
+}
+
+void hmp_info_usb(Monitor *mon, const QDict *qdict)
+{
+    monitor_printf(mon, "Support for USB devices not built-in\n");
+}