diff --git a/Makefile b/Makefile
index 591d64b4..fa56a237 100644
--- a/Makefile
+++ b/Makefile
@@ -13,7 +13,7 @@ DOCKER_RUN_BASE := docker run -e UID=$(UID) -e GID=$(GID) -v $(PWD):/home/build/
 GO_BUILD_CMD := cd /home/build/NanoKVM/server && go mod tidy && CGO_ENABLED=1 GOOS=linux GOARCH=riscv64 CC=riscv64-unknown-linux-musl-gcc CGO_CFLAGS="-mcpu=c906fdv -march=rv64imafdcv0p7xthead -mcmodel=medany -mabi=lp64d" go build
 SUPPORT_BUILD_CMD := . ./home/build/MaixCDK/bin/activate && cd /home/build/NanoKVM/support/sg2002 && ./build kvm_system && ./build kvm_system add_to_kvmapp
 
-.PHONY: help check-root builder-image rebuild-image check-image shell app support all clean
+.PHONY: help check-root builder-image rebuild-image check-image shell app support all test-usb-scripts clean
 
 # Default target
 all: app support
@@ -31,6 +31,7 @@ help:
 	@echo "  app           - Build Go application server"
 	@echo "  support       - Build hardware support libraries"
 	@echo "  all           - Build both app and support (default)"
+	@echo "  test-usb-scripts - Run USB init script regression tests"
 	@echo "  clean         - Clean build artifacts"
 	@echo ""
 	@echo "Prerequisites:"
@@ -83,6 +84,10 @@ support: check-root builder-image
 	@echo "Building support..."
 	@$(DOCKER_RUN_BASE) -it $(IMAGE_NAME) /bin/bash -c '$(SUPPORT_BUILD_CMD)'
 
+test-usb-scripts:
+	@echo "Running USB init script tests..."
+	@sh tests/usb-init-scripts-test.sh
+
 # Clean build artifacts
 clean:
 	@echo "Cleaning build artifacts..."
@@ -94,4 +99,4 @@ clean:
 		rm -rf support/sg2002/build; \
 		echo "Removed support/sg2002/build"; \
 	fi
-	@echo "Clean completed."
\ No newline at end of file
+	@echo "Clean completed."
diff --git a/kvmapp/system/init.d/S03usb-common b/kvmapp/system/init.d/S03usb-common
new file mode 100644
index 00000000..5783eaa1
--- /dev/null
+++ b/kvmapp/system/init.d/S03usb-common
@@ -0,0 +1,225 @@
+#!/bin/sh
+# shellcheck disable=SC2034
+
+USB_BOOT_DIR="${USB_BOOT_DIR:-/boot}"
+USB_GADGET_ROOT="${USB_GADGET_ROOT:-/sys/kernel/config/usb_gadget}"
+USB_GADGET_NAME="${USB_GADGET_NAME:-g0}"
+USB_UDC_CLASS="${USB_UDC_CLASS:-/sys/class/udc}"
+USB_OTG_ROLE="${USB_OTG_ROLE:-/proc/cviusb/otg_role}"
+USB_PHY_DEVICE="${USB_PHY_DEVICE:-4340000.usb}"
+USB_DWC2_BIND="${USB_DWC2_BIND:-/sys/bus/platform/drivers/dwc2/bind}"
+USB_DWC2_UNBIND="${USB_DWC2_UNBIND:-/sys/bus/platform/drivers/dwc2/unbind}"
+PATH="/sbin:/usr/sbin:/bin:/usr/bin${PATH:+:${PATH}}"
+export PATH
+
+USB_DEFAULT_VENDOR_ID='0x3346'
+USB_DEFAULT_PRODUCT_ID='0x1009'
+USB_SERIAL_NUMBER='0123456789ABCDEF'
+USB_MANUFACTURER='sipeed'
+USB_PRODUCT='NanoKVM'
+USB_CONFIGURATION='NanoKVM'
+
+USB_NORMAL_BCD_USB='0x0200'
+USB_NORMAL_BCD_DEVICE='0x0510'
+USB_NORMAL_CONFIG_ATTRIBUTES='0xE0'
+USB_NORMAL_MAX_POWER='120'
+USB_HID_ONLY_BCD_USB='0x0110'
+USB_HID_ONLY_BCD_DEVICE='0x0623'
+USB_HID_ONLY_CONFIG_ATTRIBUTES='0xA0'
+USB_HID_ONLY_MAX_POWER='200'
+
+USB_HID_KEYBOARD_FUNC='hid.GS0'
+USB_HID_RELATIVE_MOUSE_FUNC='hid.GS1'
+USB_HID_ABSOLUTE_MOUSE_FUNC='hid.GS2'
+USB_HID_BOOT_SUBCLASS='1'
+USB_HID_NON_BOOT_SUBCLASS='0'
+USB_HID_KEYBOARD_PROTOCOL='1'
+USB_HID_MOUSE_PROTOCOL='2'
+USB_HID_KEYBOARD_REPORT_LENGTH='8'
+USB_HID_RELATIVE_MOUSE_REPORT_LENGTH='4'
+USB_HID_ABSOLUTE_MOUSE_REPORT_LENGTH='6'
+
+USB_HID_REPORT_NORMAL_KEYBOARD='normal-keyboard'
+USB_HID_REPORT_HID_ONLY_KEYBOARD='hid-only-keyboard'
+USB_HID_REPORT_RELATIVE_MOUSE='relative-mouse'
+USB_HID_REPORT_NORMAL_ABSOLUTE_MOUSE='normal-absolute-mouse'
+USB_HID_REPORT_HID_ONLY_ABSOLUTE_MOUSE='hid-only-absolute-mouse'
+
+remove_existing_gadget(){
+    gadget="${USB_GADGET_ROOT}/${USB_GADGET_NAME}"
+    [ -d "${gadget}" ] || return 0
+
+    echo '' > "${gadget}/UDC" 2>/dev/null || true
+    if [ -d "${gadget}/os_desc" ]
+    then
+        find "${gadget}/os_desc" -mindepth 1 -maxdepth 1 -type l -exec rm {} \;
+    fi
+    if [ -d "${gadget}/configs/c.1" ]
+    then
+        find "${gadget}/configs/c.1" -mindepth 1 -maxdepth 1 -type l -exec rm {} \;
+        rmdir "${gadget}/configs/c.1/strings/0x409" 2>/dev/null || true
+        rmdir "${gadget}/configs/c.1/strings" 2>/dev/null || true
+        rmdir "${gadget}/configs/c.1" 2>/dev/null || true
+    fi
+
+    if [ -d "${gadget}/functions" ]
+    then
+        for func in "${gadget}/functions"/*
+        do
+            [ -d "${func}" ] || continue
+            rmdir "${func}/lun.0" 2>/dev/null || true
+            rmdir "${func}" 2>/dev/null || true
+        done
+    fi
+
+    rmdir "${gadget}/strings/0x409" 2>/dev/null || true
+    rmdir "${gadget}/strings" 2>/dev/null || true
+    rmdir "${gadget}/configs" 2>/dev/null || true
+    rmdir "${gadget}/functions" 2>/dev/null || true
+    rmdir "${gadget}" 2>/dev/null || true
+}
+
+write_usb_strings(){
+    mkdir strings/0x409
+    printf '%s' "${USB_SERIAL_NUMBER}" > strings/0x409/serialnumber
+    printf '%s' "${USB_MANUFACTURER}" > strings/0x409/manufacturer
+    printf '%s' "${USB_PRODUCT}" > strings/0x409/product
+}
+
+write_usb_config_string(){
+    mkdir -p configs/c.1/strings/0x409
+    printf '%s' "${USB_CONFIGURATION}" > configs/c.1/strings/0x409/configuration
+}
+
+write_boot_or_default(){
+    if [ -e "${USB_BOOT_DIR}/$2" ]
+    then
+        cat "${USB_BOOT_DIR}/$2" > "$1"
+    else
+        echo "$3" > "$1"
+    fi
+}
+
+prepare_usb_gadget(){
+    echo "usb mode: device"
+    cd "${USB_GADGET_ROOT}" || exit 1
+    remove_existing_gadget
+    mkdir "${USB_GADGET_NAME}"
+    cd "${USB_GADGET_NAME}" || exit 1
+
+    echo "$1" > bcdUSB
+    echo "$2" > bcdDevice
+    write_boot_or_default idVendor usb.vid "${USB_DEFAULT_VENDOR_ID}"
+    write_boot_or_default idProduct usb.pid "${USB_DEFAULT_PRODUCT_ID}"
+    write_usb_strings
+
+    mkdir configs/c.1
+    echo "$3" > configs/c.1/bmAttributes
+    echo "$4" > configs/c.1/MaxPower
+    write_usb_config_string
+}
+
+set_hid_wakeup(){
+    if [ ! -e "${USB_BOOT_DIR}/usb.notwakeup" ] && [ -e "functions/$1/wakeup_on_write" ]
+    then
+        echo 1 > "functions/$1/wakeup_on_write"
+    fi
+}
+
+add_hid_function(){
+    func="$1"
+    subclass="$2"
+    protocol="$3"
+    report_length="$4"
+    report_desc="$5"
+
+    mkdir "functions/${func}"
+    echo "${subclass}" > "functions/${func}/subclass"
+    set_hid_wakeup "${func}"
+    echo "${protocol}" > "functions/${func}/protocol"
+    echo "${report_length}" > "functions/${func}/report_length"
+    write_hid_report_desc "${report_desc}" > "functions/${func}/report_desc"
+    ln -s "functions/${func}" configs/c.1
+}
+
+write_hid_report_desc(){
+    case "$1" in
+      "${USB_HID_REPORT_NORMAL_KEYBOARD}")
+        printf '%b' '\005\001\011\006\241\001\005\007\031\340\051\347\025\000\045\001\165\001\225\010\201\002\225\001\165\010\201\003\225\005\165\001\005\010\031\001\051\005\221\002\225\001\165\003\221\003\225\006\165\010\025\000\045\347\005\007\031\000\051\347\201\000\300'
+        ;;
+      "${USB_HID_REPORT_HID_ONLY_KEYBOARD}")
+        printf '%b' '\005\001\011\006\241\001\005\007\031\340\051\347\025\000\045\001\165\001\225\010\201\002\225\001\165\010\201\003\225\005\165\001\005\010\031\001\051\005\221\002\225\001\165\003\221\003\225\006\165\010\025\000\045\145\005\007\031\000\051\145\201\000\300'
+        ;;
+      "${USB_HID_REPORT_RELATIVE_MOUSE}")
+        printf '%b' '\005\001\011\002\241\001\011\001\241\000\005\011\031\001\051\003\025\000\045\001\225\003\165\001\201\002\225\001\165\005\201\003\005\001\011\060\011\061\011\070\025\201\045\177\165\010\225\003\201\006\300\300'
+        ;;
+      "${USB_HID_REPORT_NORMAL_ABSOLUTE_MOUSE}")
+        printf '%b' '\005\001\011\002\241\001\011\001\241\000\005\011\031\001\051\005\025\000\045\001\225\005\165\001\201\002\225\001\165\003\201\001\005\001\011\060\011\061\025\000\046\377\177\065\000\106\377\177\165\020\225\002\201\002\005\001\011\070\025\201\045\177\065\000\105\000\165\010\225\001\201\006\300\300'
+        ;;
+      "${USB_HID_REPORT_HID_ONLY_ABSOLUTE_MOUSE}")
+        printf '%b' '\005\001\011\002\241\001\011\001\241\000\005\011\031\001\051\003\025\000\045\001\225\003\165\001\201\002\225\001\165\005\201\001\005\001\011\060\011\061\025\000\046\377\177\065\000\106\377\177\165\020\225\002\201\002\005\001\011\070\025\201\045\177\065\000\105\000\165\010\225\001\201\006\300\300'
+        ;;
+      *) echo "unknown HID report descriptor: $1" >&2; return 1 ;;
+    esac
+}
+
+add_hid_functions(){
+    keyboard_report="$1"
+    absolute_mouse_report="$2"
+    add_hid_function "${USB_HID_KEYBOARD_FUNC}" "${USB_HID_BOOT_SUBCLASS}" "${USB_HID_KEYBOARD_PROTOCOL}" "${USB_HID_KEYBOARD_REPORT_LENGTH}" "${keyboard_report}"
+    add_hid_function "${USB_HID_RELATIVE_MOUSE_FUNC}" "${USB_HID_BOOT_SUBCLASS}" "${USB_HID_MOUSE_PROTOCOL}" "${USB_HID_RELATIVE_MOUSE_REPORT_LENGTH}" "${USB_HID_REPORT_RELATIVE_MOUSE}"
+    add_hid_function "${USB_HID_ABSOLUTE_MOUSE_FUNC}" "${USB_HID_NON_BOOT_SUBCLASS}" "${USB_HID_MOUSE_PROTOCOL}" "${USB_HID_ABSOLUTE_MOUSE_REPORT_LENGTH}" "${absolute_mouse_report}"
+}
+
+first_udc(){ find "${USB_UDC_CLASS}" -mindepth 1 -maxdepth 1 -exec basename {} \; | sort | sed -n '1p'; }
+
+bind_first_udc(){
+    udc=$(first_udc)
+    [ -n "${udc}" ] || return 1
+    printf '%s' "${udc}" > UDC
+    echo device > "${USB_OTG_ROLE}"
+}
+
+unbind_udc(){
+    echo '' > "${USB_GADGET_ROOT}/${USB_GADGET_NAME}/UDC"
+}
+
+start_usb_host(){
+    unbind_udc
+    echo host > "${USB_OTG_ROLE}"
+}
+
+restart_udc(){
+    echo '' > "${USB_GADGET_ROOT}/${USB_GADGET_NAME}/UDC"
+    sleep 1
+    udc=$(first_udc)
+    [ -n "${udc}" ] || return 1
+    printf '%s' "${udc}" > "${USB_GADGET_ROOT}/${USB_GADGET_NAME}/UDC"
+}
+
+restart_usb_dev(){
+    restart_udc
+    echo "USB Restart OK!"
+}
+
+restart_usb_phy(){
+    command -v start_usb_dev >/dev/null || {
+        echo "start_usb_dev is not defined" >&2
+        return 1
+    }
+    echo "${USB_PHY_DEVICE}" > "${USB_DWC2_UNBIND}"
+    sleep 1
+    echo "${USB_PHY_DEVICE}" > "${USB_DWC2_BIND}"
+    start_usb_host
+    start_usb_dev
+}
+
+run_usb_action(){
+    case "$1" in
+      start) start_usb_dev ;;
+      restart) restart_usb_dev ;;
+      stop) start_usb_host ;;
+      stop_start) start_usb_host; start_usb_dev ;;
+      restart_phy) restart_usb_phy ;;
+    esac
+}
diff --git a/kvmapp/system/init.d/S03usbdev b/kvmapp/system/init.d/S03usbdev
index e4a2c834..ca7c2dc7 100755
--- a/kvmapp/system/init.d/S03usbdev
+++ b/kvmapp/system/init.d/S03usbdev
@@ -1,179 +1,77 @@
 #!/bin/sh
 # kvmhwd Rev2.2
 
-start_usb_dev(){
-    . /etc/profile
-    echo "usb mode: device"
-    cd /sys/kernel/config/usb_gadget
+# shellcheck source=/kvmapp/system/init.d/S03usb-common
+. "${USB_COMMON:-/kvmapp/system/init.d/S03usb-common}"
 
-    mkdir g0
-    cd g0
+USB_NCM_FUNC='ncm.usb0'
+USB_RNDIS_FUNC='rndis.usb0'
+USB_MASS_STORAGE_FUNC='mass_storage.disk0'
+USB_MASS_STORAGE_INQUIRY='NanoKVM USB Mass Storage0520'
+USB_LEGACY_EMPTY_DISK_BACKING='/dev/mmcblk0p3'
 
-    # echo 0x3346 > idVendor
-    # echo 0x1009 > idProduct
-    if [ -e /boot/usb.vid ]
-    then
-        cat /boot/usb.vid > idVendor
-    else
-        echo 0x3346 > idVendor
-    fi
-    if [ -e /boot/usb.pid ]
-    then
-        cat /boot/usb.pid > idProduct
-    else
-        echo 0x1009 > idProduct
-    fi
+start_usb_dev(){
+    prepare_usb_gadget "${USB_NORMAL_BCD_USB}" "${USB_NORMAL_BCD_DEVICE}" "${USB_NORMAL_CONFIG_ATTRIBUTES}" "${USB_NORMAL_MAX_POWER}"
 
     echo 0xEF > bDeviceClass
     echo 0x02 > bDeviceSubClass
     echo 0x01 > bDeviceProtocol
 
-    mkdir strings/0x409
-    echo '0123456789ABCDEF' > strings/0x409/serialnumber
-    echo 'sipeed' > strings/0x409/manufacturer
-    echo 'NanoKVM' > strings/0x409/product
-
-    mkdir configs/c.1
-    echo 0xE0 > configs/c.1/bmAttributes
-    echo 120 > configs/c.1/MaxPower
-    mkdir configs/c.1/strings/0x409
-    echo "NanoKVM" >  configs/c.1/strings/0x409/configuration
-
-    if [ -e /boot/usb.ncm ]
+    if [ -e "${USB_BOOT_DIR}/usb.ncm" ]
     then
-        mkdir functions/ncm.usb0
-        echo WINNCM > functions/ncm.usb0/os_desc/interface.ncm/compatible_id
-        ln -s functions/ncm.usb0 configs/c.1/
-    else
-        if [ -e /boot/usb.rndis0 ]
-        then
-                mkdir functions/rndis.usb0
-                echo e0 > functions/rndis.usb0/class
-                echo 01 > functions/rndis.usb0/subclass
-                echo 03 > functions/rndis.usb0/protocol
-                echo RNDIS > functions/rndis.usb0/os_desc/interface.rndis/compatible_id
-                echo 5162001 > functions/rndis.usb0/os_desc/interface.rndis/sub_compatible_id
-                ln -s functions/rndis.usb0 configs/c.1/
-        fi
+        mkdir "functions/${USB_NCM_FUNC}"
+        echo WINNCM > "functions/${USB_NCM_FUNC}/os_desc/interface.ncm/compatible_id"
+        ln -s "functions/${USB_NCM_FUNC}" configs/c.1/
+    elif [ -e "${USB_BOOT_DIR}/usb.rndis0" ]
+    then
+        mkdir "functions/${USB_RNDIS_FUNC}"
+        echo e0 > "functions/${USB_RNDIS_FUNC}/class"
+        echo 01 > "functions/${USB_RNDIS_FUNC}/subclass"
+        echo 03 > "functions/${USB_RNDIS_FUNC}/protocol"
+        echo RNDIS > "functions/${USB_RNDIS_FUNC}/os_desc/interface.rndis/compatible_id"
+        echo 5162001 > "functions/${USB_RNDIS_FUNC}/os_desc/interface.rndis/sub_compatible_id"
+        ln -s "functions/${USB_RNDIS_FUNC}" configs/c.1/
     fi
 
-    if [ -e /boot/usb.ncm ] || [ -e /boot/usb.rndis0 ]
+    if [ -e "${USB_BOOT_DIR}/usb.ncm" ] || [ -e "${USB_BOOT_DIR}/usb.rndis0" ]
     then
-        # Microsoft OS 2.0 Descriptor
         echo 1 > os_desc/use
         echo 0xCD > os_desc/b_vendor_code
         echo MSFT100 > os_desc/qw_sign
         ln -s configs/c.1 os_desc
     fi
 
-    if [ ! -e /boot/disable_hid ]
+    if [ ! -e "${USB_BOOT_DIR}/disable_hid" ]
     then
-        # keyboard
-        mkdir functions/hid.GS0
-        if [ -e /boot/BIOS ]
-        then
-            echo 1 > functions/hid.GS0/subclass
-        fi
-        if [ ! -e /boot/usb.notwakeup ]
-        then
-            echo 1 > functions/hid.GS0/wakeup_on_write
-        fi
-        echo 1 > functions/hid.GS0/protocol
-        echo 8 > functions/hid.GS0/report_length
-        echo -ne \\x05\\x01\\x09\\x06\\xa1\\x01\\x05\\x07\\x19\\xe0\\x29\\xe7\\x15\\x00\\x25\\x01\\x75\\x01\\x95\\x08\\x81\\x02\\x95\\x01\\x75\\x08\\x81\\x03\\x95\\x05\\x75\\x01\\x05\\x08\\x19\\x01\\x29\\x05\\x91\\x02\\x95\\x01\\x75\\x03\\x91\\x03\\x95\\x06\\x75\\x08\\x15\\x00\\x25\\xE7\\x05\\x07\\x19\\x00\\x29\\xE7\\x81\\x00\\xc0 > functions/hid.GS0/report_desc
-        ln -s functions/hid.GS0 configs/c.1
-
-        # mouse
-        mkdir functions/hid.GS1
-        if [ -e /boot/BIOS ]
-        then
-            echo 1 > functions/hid.GS1/subclass
-        fi
-        if [ ! -e /boot/usb.notwakeup ]
-        then
-            echo 1 > functions/hid.GS1/wakeup_on_write
-        fi
-        echo 2 > functions/hid.GS1/protocol
-        echo 4 > functions/hid.GS1/report_length
-        echo -ne \\x5\\x1\\x9\\x2\\xa1\\x1\\x9\\x1\\xa1\\x0\\x5\\x9\\x19\\x1\\x29\\x3\\x15\\x0\\x25\\x1\\x95\\x3\\x75\\x1\\x81\\x2\\x95\\x1\\x75\\x5\\x81\\x3\\x5\\x1\\x9\\x30\\x9\\x31\\x9\\x38\\x15\\x81\\x25\\x7f\\x75\\x8\\x95\\x3\\x81\\x6\\xc0\\xc0 > functions/hid.GS1/report_desc
-        ln -s functions/hid.GS1 configs/c.1
+        add_hid_functions "${USB_HID_REPORT_NORMAL_KEYBOARD}" "${USB_HID_REPORT_NORMAL_ABSOLUTE_MOUSE}"
+    fi
 
-        # touchpad
-        mkdir functions/hid.GS2
-        if [ -e /boot/BIOS ]
+    if [ -e "${USB_BOOT_DIR}/usb.disk0" ]
+    then
+        mkdir "functions/${USB_MASS_STORAGE_FUNC}"
+        ln -s "functions/${USB_MASS_STORAGE_FUNC}" configs/c.1/
+        echo 1 > "functions/${USB_MASS_STORAGE_FUNC}/lun.0/removable"
+        if [ -e "${USB_BOOT_DIR}/usb.disk0.ro" ]
         then
-            echo 1 > functions/hid.GS2/subclass
+            echo 1 > "functions/${USB_MASS_STORAGE_FUNC}/lun.0/ro"
+            echo 0 > "functions/${USB_MASS_STORAGE_FUNC}/lun.0/cdrom"
         fi
-        if [ ! -e /boot/usb.notwakeup ]
+        echo "${USB_MASS_STORAGE_INQUIRY}" > "functions/${USB_MASS_STORAGE_FUNC}/lun.0/inquiry_string"
+        disk=$(cat "${USB_BOOT_DIR}/usb.disk0")
+        if [ -z "${disk}" ]
         then
-            echo 1 > functions/hid.GS2/wakeup_on_write
+            # if [ ! -e /mnt/usbdisk.img ]
+            # then
+            #         fallocate -l 8G /mnt/usbdisk.img
+            #         mkfs.vfat /mnt/usbdisk.img
+            # fi
+            echo "${USB_LEGACY_EMPTY_DISK_BACKING}" > "functions/${USB_MASS_STORAGE_FUNC}/lun.0/file"
+        else
+            printf '%s' "${disk}" > "functions/${USB_MASS_STORAGE_FUNC}/lun.0/file"
         fi
-        echo 2 > functions/hid.GS2/protocol
-        echo 6 > functions/hid.GS2/report_length
-        echo -ne \\x05\\x01\\x09\\x02\\xa1\\x01\\x09\\x01\\xa1\\x00\\x05\\x09\\x19\\x01\\x29\\x05\\x15\\x00\\x25\\x01\\x95\\x05\\x75\\x01\\x81\\x02\\x95\\x01\\x75\\x03\\x81\\x01\\x05\\x01\\x09\\x30\\x09\\x31\\x15\\x00\\x26\\xff\\x7f\\x35\\x00\\x46\\xff\\x7f\\x75\\x10\\x95\\x02\\x81\\x02\\x05\\x01\\x09\\x38\\x15\\x81\\x25\\x7f\\x35\\x00\\x45\\x00\\x75\\x08\\x95\\x01\\x81\\x06\\xc0\\xc0 > functions/hid.GS2/report_desc
-        ln -s functions/hid.GS2 configs/c.1
     fi
 
-    if [ -e /boot/usb.disk0 ]
-    then
-            mkdir functions/mass_storage.disk0
-            ln -s functions/mass_storage.disk0 configs/c.1/
-            echo 1 > functions/mass_storage.disk0/lun.0/removable
-            if [ -e /boot/usb.disk0.ro ]
-            then
-                    echo 1 > functions/mass_storage.disk0/lun.0/ro
-                    echo 0 > functions/mass_storage.disk0/lun.0/cdrom
-            fi
-            echo "NanoKVM USB Mass Storage0520" > functions/mass_storage.disk0/lun.0/inquiry_string
-            disk=$(cat /boot/usb.disk0)
-            if [ -z "${disk}" ]
-            then
-                    # if [ ! -e /mnt/usbdisk.img ]
-                    # then
-                    #         fallocate -l 8G /mnt/usbdisk.img
-                    #         mkfs.vfat /mnt/usbdisk.img
-                    # fi
-                    echo /dev/mmcblk0p3 > functions/mass_storage.disk0/lun.0/file
-            else
-                    cat /boot/usb.disk0 > functions/mass_storage.disk0/lun.0/file
-            fi
-    fi
-
-    ls /sys/class/udc/ | cat > UDC
-    echo device > /proc/cviusb/otg_role
-}
-
-start_usb_host(){
-    echo '' > /sys/kernel/config/usb_gadget/g0/UDC
-    echo host > /proc/cviusb/otg_role
-}
-
-restart_usb_dev(){
-    echo > /sys/kernel/config/usb_gadget/g0/UDC
-    sleep 1
-    ls /sys/class/udc/ | cat > /sys/kernel/config/usb_gadget/g0/UDC
-    echo "USB Restart OK!"
+    bind_first_udc
 }
 
-case "$1" in
-  start)
-    start_usb_dev
-  ;;
-  restart)
-    restart_usb_dev
-  ;;
-  stop)
-    start_usb_host
-  ;;
-  stop_start)
-    start_usb_host
-    start_usb_dev
-  ;;
-   restart_phy)
-    echo "4340000.usb" > /sys/bus/platform/drivers/dwc2/unbind
-    sleep 1
-    echo "4340000.usb" > /sys/bus/platform/drivers/dwc2/bind
-    start_usb_host
-    start_usb_dev
-  ;;
-esac
+run_usb_action "$1"
diff --git a/kvmapp/system/init.d/S03usbhid b/kvmapp/system/init.d/S03usbhid
index b5f160e8..8f1179b1 100755
--- a/kvmapp/system/init.d/S03usbhid
+++ b/kvmapp/system/init.d/S03usbhid
@@ -1,112 +1,13 @@
 #!/bin/sh
 # kvmhwd hid only
 
-start_usb_dev(){
-    . /etc/profile
-    echo "usb mode: device"
-    cd /sys/kernel/config/usb_gadget
-
-    mkdir g0
-    cd g0
-
-    echo 0x0101 > bcdUSB
-    echo 0x0623 > bcdDevice
-    # echo 0x3346 > idVendor
-    # echo 0x1009 > idProduct
-    if [ -e /boot/usb.vid ]
-    then
-        cat /boot/usb.vid > idVendor
-    else
-        echo 0x3346 > idVendor
-    fi
-    if [ -e /boot/usb.pid ]
-    then
-        cat /boot/usb.pid > idProduct
-    else
-        echo 0x1009 > idProduct
-    fi
-    mkdir strings/0x409
-    # echo '0' > strings/0x409/serialnumber
-    echo 'sipeed' > strings/0x409/manufacturer
-    echo 'NanoKVM' > strings/0x409/product
-
-    mkdir configs/c.1
-    echo 0xA0 > configs/c.1/bmAttributes
-    echo 200 > configs/c.1/MaxPower
-    mkdir configs/c.1/strings/0x409
-    echo "NanoKVM" >  configs/c.1/strings/0x409/configuration
-
-    # keyboard
-    mkdir functions/hid.GS0
-    echo 1 > functions/hid.GS0/subclass
-    if [ ! -e /boot/usb.notwakeup ]
-    then
-        echo 1 > functions/hid.GS0/wakeup_on_write
-    fi
-    echo 1 > functions/hid.GS0/protocol
-    echo 8 > functions/hid.GS0/report_length
-    echo -ne \\x05\\x01\\x09\\x06\\xa1\\x01\\x05\\x07\\x19\\xe0\\x29\\xe7\\x15\\x00\\x25\\x01\\x75\\x01\\x95\\x08\\x81\\x02\\x95\\x01\\x75\\x08\\x81\\x03\\x95\\x05\\x75\\x01\\x05\\x08\\x19\\x01\\x29\\x05\\x91\\x02\\x95\\x01\\x75\\x03\\x91\\x03\\x95\\x06\\x75\\x08\\x15\\x00\\x25\\x65\\x05\\x07\\x19\\x00\\x29\\x65\\x81\\x00\\xc0 > functions/hid.GS0/report_desc
-    ln -s functions/hid.GS0 configs/c.1
-
-    # mouse
-    mkdir functions/hid.GS1
-    echo 1 > functions/hid.GS1/subclass
-    if [ ! -e /boot/usb.notwakeup ]
-    then
-        echo 1 > functions/hid.GS1/wakeup_on_write
-    fi
-    echo 2 > functions/hid.GS1/protocol
-    echo 4 > functions/hid.GS1/report_length
-    echo -ne \\x5\\x1\\x9\\x2\\xa1\\x1\\x9\\x1\\xa1\\x0\\x5\\x9\\x19\\x1\\x29\\x3\\x15\\x0\\x25\\x1\\x95\\x3\\x75\\x1\\x81\\x2\\x95\\x1\\x75\\x5\\x81\\x3\\x5\\x1\\x9\\x30\\x9\\x31\\x9\\x38\\x15\\x81\\x25\\x7f\\x75\\x8\\x95\\x3\\x81\\x6\\xc0\\xc0 > functions/hid.GS1/report_desc
-    ln -s functions/hid.GS1 configs/c.1
+# shellcheck source=/kvmapp/system/init.d/S03usb-common
+. "${USB_COMMON:-/kvmapp/system/init.d/S03usb-common}"
 
-    # touchpad
-    mkdir functions/hid.GS2
-    echo 1 > functions/hid.GS2/subclass
-    if [ ! -e /boot/usb.notwakeup ]
-    then
-        echo 1 > functions/hid.GS2/wakeup_on_write
-    fi
-    echo 2 > functions/hid.GS2/protocol
-    echo 6 > functions/hid.GS2/report_length
-    echo -ne \\x05\\x01\\x09\\x02\\xa1\\x01\\x09\\x01\\xa1\\x00\\x05\\x09\\x19\\x01\\x29\\x03\\x15\\x00\\x25\\x01\\x95\\x03\\x75\\x01\\x81\\x02\\x95\\x01\\x75\\x05\\x81\\x01\\x05\\x01\\x09\\x30\\x09\\x31\\x15\\x00\\x26\\xff\\x7f\\x35\\x00\\x46\\xff\\x7f\\x75\\x10\\x95\\x02\\x81\\x02\\x05\\x01\\x09\\x38\\x15\\x81\\x25\\x7f\\x35\\x00\\x45\\x00\\x75\\x08\\x95\\x01\\x81\\x06\\xc0\\xc0 > functions/hid.GS2/report_desc
-    ln -s functions/hid.GS2 configs/c.1
-
-    ls /sys/class/udc/ | cat > UDC
-    echo device > /proc/cviusb/otg_role
-}
-
-start_usb_host(){
-    echo '' > /sys/kernel/config/usb_gadget/g0/UDC
-    echo host > /proc/cviusb/otg_role
-}
-
-restart_usb_dev(){
-    echo > /sys/kernel/config/usb_gadget/g0/UDC
-    sleep 1
-    ls /sys/class/udc/ | cat > /sys/kernel/config/usb_gadget/g0/UDC
-    echo "USB Restart OK!"
+start_usb_dev(){
+    prepare_usb_gadget "${USB_HID_ONLY_BCD_USB}" "${USB_HID_ONLY_BCD_DEVICE}" "${USB_HID_ONLY_CONFIG_ATTRIBUTES}" "${USB_HID_ONLY_MAX_POWER}"
+    add_hid_functions "${USB_HID_REPORT_HID_ONLY_KEYBOARD}" "${USB_HID_REPORT_HID_ONLY_ABSOLUTE_MOUSE}"
+    bind_first_udc
 }
 
-case "$1" in
-  start)
-    start_usb_dev
-  ;;
-  restart)
-    restart_usb_dev
-  ;;
-  stop)
-    start_usb_host
-  ;;
-  stop_start)
-    start_usb_host
-    start_usb_dev
-  ;;
-   restart_phy)
-    echo "4340000.usb" > /sys/bus/platform/drivers/dwc2/unbind
-    sleep 1
-    echo "4340000.usb" > /sys/bus/platform/drivers/dwc2/bind
-    start_usb_host
-    start_usb_dev
-  ;;
-esac
+run_usb_action "$1"
diff --git a/server/service/hid/hid.go b/server/service/hid/hid.go
index 60185ba8..6efd6ca6 100644
--- a/server/service/hid/hid.go
+++ b/server/service/hid/hid.go
@@ -5,6 +5,7 @@ import (
 	"fmt"
 	"io"
 	"os"
+	"strings"
 	"sync"
 	"syscall"
 	"time"
@@ -193,6 +194,24 @@ func (h *Hid) closeDeviceNoLock(device hidDevice) {
 	}
 }
 
+func (h *Hid) closeDeletedDeviceNoLock(device hidDevice) {
+	file := device.get()
+	if file == nil || !hidFileWasDeleted(file) {
+		return
+	}
+
+	log.Debugf("close %s because the cached HID handle was deleted", device.path)
+	h.closeDeviceNoLock(device)
+}
+
+func hidFileWasDeleted(file *os.File) bool {
+	target, err := os.Readlink(fmt.Sprintf("/proc/self/fd/%d", file.Fd()))
+	if err != nil {
+		return false
+	}
+	return strings.HasSuffix(target, " (deleted)")
+}
+
 // writeWithTimeout bounds how long callers hold HID locks when writing to a
 // nonblocking descriptor. EAGAIN means the host is not accepting HID reports
 // yet, so retry until the caller's deadline expires.
@@ -230,6 +249,15 @@ func isRetryableWriteError(err error) bool {
 	return errors.Is(err, syscall.EAGAIN) || errors.Is(err, syscall.EWOULDBLOCK)
 }
 
+func isStaleHIDWriteError(err error) bool {
+	return errors.Is(err, os.ErrClosed) ||
+		errors.Is(err, syscall.EIO) ||
+		errors.Is(err, syscall.ENODEV) ||
+		errors.Is(err, syscall.ENXIO) ||
+		errors.Is(err, syscall.EPIPE) ||
+		errors.Is(err, syscall.ESHUTDOWN)
+}
+
 func (h *Hid) Open() {
 	h.kbMutex.Lock()
 	defer h.kbMutex.Unlock()
@@ -272,10 +300,31 @@ func (h *Hid) writeHID(device hidDevice, data []byte) error {
 	device.mu.Lock()
 	defer device.mu.Unlock()
 
+	h.closeDeletedDeviceNoLock(device)
 	if err := h.openDeviceNoLock(device); err != nil {
 		return err
 	}
 
+	if err := h.writeHIDNoLock(device, data); err != nil {
+		h.closeDeviceNoLock(device)
+		if !isStaleHIDWriteError(err) {
+			return formatHIDWriteError(err)
+		}
+
+		if reopenErr := h.openDeviceNoLock(device); reopenErr != nil {
+			return fmt.Errorf("reopen %s after stale HID write: %w", device.path, reopenErr)
+		}
+		if retryErr := h.writeHIDNoLock(device, data); retryErr != nil {
+			h.closeDeviceNoLock(device)
+			return formatHIDWriteError(retryErr)
+		}
+	}
+
+	log.Debugf("write to %s: %v", device.path, data)
+	return nil
+}
+
+func (h *Hid) writeHIDNoLock(device hidDevice, data []byte) error {
 	file := device.get()
 	if file == nil {
 		return fmt.Errorf("%s: hid handle is nil", device.path)
@@ -287,17 +336,19 @@ func (h *Hid) writeHID(device hidDevice, data []byte) error {
 	}
 
 	if err := writeWithTimeout(file, data, hidWriteTimeout); err != nil {
-		h.closeDeviceNoLock(device)
-		switch {
-		case errors.Is(err, os.ErrClosed):
-			return fmt.Errorf("hid already closed: %w", err)
-		case errors.Is(err, os.ErrDeadlineExceeded):
-			return fmt.Errorf("timeout after %s: %w", hidWriteTimeout, err)
-		default:
-			return err
-		}
+		return err
 	}
 
-	log.Debugf("write to %s: %v", device.path, data)
 	return nil
 }
+
+func formatHIDWriteError(err error) error {
+	switch {
+	case errors.Is(err, os.ErrClosed):
+		return fmt.Errorf("hid already closed: %w", err)
+	case errors.Is(err, os.ErrDeadlineExceeded):
+		return fmt.Errorf("timeout after %s: %w", hidWriteTimeout, err)
+	default:
+		return err
+	}
+}
diff --git a/server/service/hid/hid_test.go b/server/service/hid/hid_test.go
new file mode 100644
index 00000000..064c95e2
--- /dev/null
+++ b/server/service/hid/hid_test.go
@@ -0,0 +1,147 @@
+package hid
+
+import (
+	"errors"
+	"io"
+	"os"
+	"runtime"
+	"syscall"
+	"testing"
+	"time"
+)
+
+type scriptedWriter struct {
+	writes []scriptedWrite
+}
+
+type scriptedWrite struct {
+	n   int
+	err error
+}
+
+func (w *scriptedWriter) Write(_ []byte) (int, error) {
+	if len(w.writes) == 0 {
+		return 0, io.ErrUnexpectedEOF
+	}
+	write := w.writes[0]
+	w.writes = w.writes[1:]
+	return write.n, write.err
+}
+
+func TestHidFileWasDeleted(t *testing.T) {
+	if runtime.GOOS != "linux" {
+		t.Skip("deleted fd detection uses /proc/self/fd")
+	}
+
+	file, err := os.CreateTemp(t.TempDir(), "hidg")
+	if err != nil {
+		t.Fatal(err)
+	}
+	if hidFileWasDeleted(file) {
+		t.Fatal("new file reported as deleted")
+	}
+
+	if err := os.Remove(file.Name()); err != nil {
+		t.Fatal(err)
+	}
+	if !hidFileWasDeleted(file) {
+		t.Fatal("unlinked open file did not report as deleted")
+	}
+}
+
+func TestIsStaleHIDWriteError(t *testing.T) {
+	tests := []struct {
+		name string
+		err  error
+		want bool
+	}{
+		{name: "closed", err: os.ErrClosed, want: true},
+		{name: "io", err: syscall.EIO, want: true},
+		{name: "no device", err: syscall.ENODEV, want: true},
+		{name: "no such device address", err: syscall.ENXIO, want: true},
+		{name: "pipe", err: syscall.EPIPE, want: true},
+		{name: "shutdown", err: syscall.ESHUTDOWN, want: true},
+		{name: "wrapped", err: errors.Join(syscall.EIO), want: true},
+		{name: "again", err: syscall.EAGAIN, want: false},
+		{name: "deadline", err: os.ErrDeadlineExceeded, want: false},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := isStaleHIDWriteError(tt.err); got != tt.want {
+				t.Fatalf("isStaleHIDWriteError(%v) = %v, want %v", tt.err, got, tt.want)
+			}
+		})
+	}
+}
+
+func TestWriteWithTimeoutRetriesEAGAIN(t *testing.T) {
+	writer := &scriptedWriter{
+		writes: []scriptedWrite{
+			{err: syscall.EAGAIN},
+			{n: 3},
+		},
+	}
+
+	if err := writeWithTimeout(writer, []byte{1, 2, 3}, 20*time.Millisecond); err != nil {
+		t.Fatal(err)
+	}
+	if len(writer.writes) != 0 {
+		t.Fatalf("unused scripted writes: %d", len(writer.writes))
+	}
+}
+
+func TestWriteWithTimeoutRejectsShortWrite(t *testing.T) {
+	writer := &scriptedWriter{
+		writes: []scriptedWrite{{n: 2}},
+	}
+
+	if !errors.Is(writeWithTimeout(writer, []byte{1, 2, 3}, 20*time.Millisecond), io.ErrShortWrite) {
+		t.Fatal("writeWithTimeout did not reject a short write")
+	}
+}
+
+func TestWriteWithTimeoutExpiresAfterRetryableErrors(t *testing.T) {
+	writer := &scriptedWriter{
+		writes: []scriptedWrite{
+			{err: syscall.EAGAIN},
+			{err: syscall.EAGAIN},
+			{err: syscall.EAGAIN},
+		},
+	}
+
+	if !errors.Is(writeWithTimeout(writer, []byte{1}, time.Millisecond), os.ErrDeadlineExceeded) {
+		t.Fatal("writeWithTimeout did not time out after retryable errors")
+	}
+}
+
+func TestOpenNoLockWithRetryRetriesUntilSuccess(t *testing.T) {
+	attempts := 0
+	err := openNoLockWithRetry(func() error {
+		attempts++
+		if attempts < 3 {
+			return syscall.ENODEV
+		}
+		return nil
+	}, 100*time.Millisecond, time.Millisecond)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if attempts != 3 {
+		t.Fatalf("attempts = %d, want 3", attempts)
+	}
+}
+
+func TestOpenNoLockWithRetryReturnsLastError(t *testing.T) {
+	attempts := 0
+	err := openNoLockWithRetry(func() error {
+		attempts++
+		return syscall.ENODEV
+	}, time.Millisecond, time.Millisecond)
+	if !errors.Is(err, syscall.ENODEV) {
+		t.Fatalf("openNoLockWithRetry error = %v, want ENODEV", err)
+	}
+	if attempts == 0 {
+		t.Fatal("openNoLockWithRetry did not attempt to open")
+	}
+}
diff --git a/server/service/hid/status.go b/server/service/hid/status.go
index 43cfce1b..da791923 100644
--- a/server/service/hid/status.go
+++ b/server/service/hid/status.go
@@ -1,23 +1,30 @@
 package hid
 
 import (
-	"NanoKVM-Server/proto"
+	"context"
 	"errors"
 	"fmt"
 	"io"
 	"os"
 	"os/exec"
+	"path/filepath"
 	"strings"
 	"time"
 
 	"github.com/gin-gonic/gin"
 	log "github.com/sirupsen/logrus"
+
+	"NanoKVM-Server/proto"
 )
 
 const (
-	ModeNormal  = "normal"
-	ModeHidOnly = "hid-only"
-	ModeFlag    = "/sys/kernel/config/usb_gadget/g0/bcdDevice"
+	ModeNormal      = "normal"
+	ModeHidOnly     = "hid-only"
+	DefaultModeFlag = "/sys/kernel/config/usb_gadget/g0/bcdDevice"
+)
+
+var (
+	modeFlag = DefaultModeFlag
 
 	ModeNormalScript  = "/kvmapp/system/init.d/S03usbdev"
 	ModeHidOnlyScript = "/kvmapp/system/init.d/S03usbhid"
@@ -120,8 +127,10 @@ func ResetUSBPHY() error {
 	h.CloseNoLock()
 	defer h.Unlock()
 
-	command := fmt.Sprintf("%s restart_phy", USBDevScript)
-	if err := exec.Command("sh", "-c", command).Run(); err != nil {
+	ctx, cancel := context.WithTimeout(context.Background(), 10*time.Second)
+	defer cancel()
+
+	if err := exec.CommandContext(ctx, "sh", USBDevScript, "restart_phy").Run(); err != nil {
 		return fmt.Errorf("restart usb phy: %w", err)
 	}
 
@@ -150,7 +159,7 @@ func copyModeFile(srcScript string) error {
 	}
 
 	// create and copy to temporary file
-	tmpFile, err := os.CreateTemp("/etc/init.d/", ".S03usbdev-")
+	tmpFile, err := os.CreateTemp(filepath.Dir(USBDevScript), ".S03usbdev-")
 	if err != nil {
 		log.Errorf("failed to create temp %s: %s", USBDevScript, err)
 		return err
@@ -195,9 +204,9 @@ func copyModeFile(srcScript string) error {
 }
 
 func getHidMode() (string, error) {
-	data, err := os.ReadFile(ModeFlag)
+	data, err := os.ReadFile(modeFlag)
 	if err != nil {
-		log.Errorf("failed to read %s: %s", ModeFlag, err)
+		log.Errorf("failed to read %s: %s", modeFlag, err)
 		return "", err
 	}
 
diff --git a/server/service/hid/status_test.go b/server/service/hid/status_test.go
new file mode 100644
index 00000000..9766d304
--- /dev/null
+++ b/server/service/hid/status_test.go
@@ -0,0 +1,146 @@
+package hid
+
+import (
+	"os"
+	"path/filepath"
+	"runtime"
+	"testing"
+)
+
+func TestGetHidMode(t *testing.T) {
+	tests := []struct {
+		name string
+		flag string
+		want string
+	}{
+		{name: "normal", flag: "0x0510\n", want: ModeNormal},
+		{name: "hid only", flag: "0x0623\n", want: ModeHidOnly},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			withModeFlag(t, tt.flag)
+
+			got, err := getHidMode()
+			if err != nil {
+				t.Fatal(err)
+			}
+			if got != tt.want {
+				t.Fatalf("getHidMode() = %q, want %q", got, tt.want)
+			}
+		})
+	}
+}
+
+func TestGetHidModeRejectsUnknownBcdDevice(t *testing.T) {
+	withModeFlag(t, "0x9999\n")
+
+	if _, err := getHidMode(); err == nil {
+		t.Fatal("getHidMode succeeded for an unknown bcdDevice")
+	}
+}
+
+func TestGetHidModeRequiresModeFlag(t *testing.T) {
+	oldModeFlag := modeFlag
+	t.Cleanup(func() {
+		modeFlag = oldModeFlag
+	})
+	modeFlag = filepath.Join(t.TempDir(), "missing-bcdDevice")
+
+	if _, err := getHidMode(); err == nil {
+		t.Fatal("getHidMode succeeded with a missing bcdDevice")
+	}
+}
+
+func TestCopyModeFileCopiesScriptAtomically(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("script mode assertions are POSIX-specific")
+	}
+
+	dir := t.TempDir()
+	src := filepath.Join(dir, "S03usbhid")
+	dst := filepath.Join(dir, "S03usbdev")
+	content := []byte("#!/bin/sh\nexit 0\n")
+	if err := os.WriteFile(src, content, 0o755); err != nil {
+		t.Fatal(err)
+	}
+	if err := os.WriteFile(dst, []byte("old"), 0o644); err != nil {
+		t.Fatal(err)
+	}
+
+	oldUSBDevScript := USBDevScript
+	t.Cleanup(func() {
+		USBDevScript = oldUSBDevScript
+	})
+	USBDevScript = dst
+
+	if err := copyModeFile(src); err != nil {
+		t.Fatal(err)
+	}
+
+	got, err := os.ReadFile(dst)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(got) != string(content) {
+		t.Fatalf("target content = %q, want %q", got, content)
+	}
+
+	info, err := os.Stat(dst)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if info.Mode().Perm() != 0o755 {
+		t.Fatalf("target mode = %v, want 0755", info.Mode().Perm())
+	}
+
+	leftovers, err := filepath.Glob(filepath.Join(dir, ".S03usbdev-*"))
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(leftovers) != 0 {
+		t.Fatalf("temporary mode files left behind: %v", leftovers)
+	}
+}
+
+func TestCopyModeFileFailureKeepsTarget(t *testing.T) {
+	dir := t.TempDir()
+	src := filepath.Join(dir, "missing")
+	dst := filepath.Join(dir, "S03usbdev")
+	oldContent := []byte("old script\n")
+	if err := os.WriteFile(dst, oldContent, 0o755); err != nil {
+		t.Fatal(err)
+	}
+
+	oldUSBDevScript := USBDevScript
+	t.Cleanup(func() {
+		USBDevScript = oldUSBDevScript
+	})
+	USBDevScript = dst
+
+	if err := copyModeFile(src); err == nil {
+		t.Fatal("copyModeFile succeeded with a missing source")
+	}
+
+	got, err := os.ReadFile(dst)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if string(got) != string(oldContent) {
+		t.Fatalf("target changed after failed copy: got %q, want %q", got, oldContent)
+	}
+}
+
+func withModeFlag(t *testing.T, content string) {
+	t.Helper()
+
+	oldModeFlag := modeFlag
+	t.Cleanup(func() {
+		modeFlag = oldModeFlag
+	})
+
+	modeFlag = filepath.Join(t.TempDir(), "bcdDevice")
+	if err := os.WriteFile(modeFlag, []byte(content), 0o666); err != nil {
+		t.Fatal(err)
+	}
+}
diff --git a/support/sg2002/kvm_system/main/lib/system_state/system_state.cpp b/support/sg2002/kvm_system/main/lib/system_state/system_state.cpp
index d98d5767..0d73dd95 100644
--- a/support/sg2002/kvm_system/main/lib/system_state/system_state.cpp
+++ b/support/sg2002/kvm_system/main/lib/system_state/system_state.cpp
@@ -10,6 +10,15 @@ using namespace maix::sys;
 extern kvm_sys_state_t kvm_sys_state;
 extern kvm_oled_state_t kvm_oled_state;
 
+static const char *USB_HID0_LINK = "/sys/kernel/config/usb_gadget/g0/configs/c.1/hid.GS0";
+static const char *USB_HID1_LINK = "/sys/kernel/config/usb_gadget/g0/configs/c.1/hid.GS1";
+static const char *USB_HID2_LINK = "/sys/kernel/config/usb_gadget/g0/configs/c.1/hid.GS2";
+
+static bool path_exists(const char *path)
+{
+	return access(path, F_OK) == 0;
+}
+
 int get_nic_state(const char* interface_name)
 {
 	int sock;
@@ -224,10 +233,12 @@ void kvm_update_usb_state()
 	else kvm_sys_state.usb_state = -1;
 	// hid_state & udisk_state (rndis_state单独处理)
 	if(kvm_sys_state.usb_state == 1){
-		if(access("/sys/kernel/config/usb_gadget/g0/configs/c.1/hid.GS*", F_OK) == 0) 
-			kvm_sys_state.hid_state = 1;
-		if(access("/sys/kernel/config/usb_gadget/g0/configs/c.1/mass_storage.disk0", F_OK) == 0) 
-			kvm_sys_state.udisk_state = 1;
+		kvm_sys_state.hid_state =
+			path_exists(USB_HID0_LINK) ||
+			path_exists(USB_HID1_LINK) ||
+			path_exists(USB_HID2_LINK);
+		kvm_sys_state.udisk_state =
+			path_exists("/sys/kernel/config/usb_gadget/g0/configs/c.1/mass_storage.disk0");
 	} else {
 		kvm_sys_state.hid_state = 0;
 		kvm_sys_state.udisk_state = 0;
@@ -519,4 +530,4 @@ int check_watchdog()
 			return -1;
 		}
 	} else return 0;
-}
\ No newline at end of file
+}
diff --git a/tests/usb-init-scripts-test.sh b/tests/usb-init-scripts-test.sh
new file mode 100644
index 00000000..90fc953a
--- /dev/null
+++ b/tests/usb-init-scripts-test.sh
@@ -0,0 +1,520 @@
+#!/bin/sh
+set -eu
+
+ROOT_DIR=$(CDPATH='' cd -- "$(dirname -- "$0")/.." && pwd)
+COMMON_SCRIPT="${ROOT_DIR}/kvmapp/system/init.d/S03usb-common"
+NORMAL_SCRIPT="${ROOT_DIR}/kvmapp/system/init.d/S03usbdev"
+HID_ONLY_SCRIPT="${ROOT_DIR}/kvmapp/system/init.d/S03usbhid"
+TMP_DIRS=""
+TEST_COMMON_SCRIPT=""
+
+CONFIGFS_GADGET_ATTRS="UDC bcdUSB bcdDevice idVendor idProduct bDeviceClass bDeviceSubClass bDeviceProtocol"
+CONFIGFS_STRING_ATTRS="serialnumber manufacturer product"
+CONFIGFS_CONFIG_ATTRS="bmAttributes MaxPower"
+CONFIGFS_CONFIG_STRING_ATTRS="configuration"
+CONFIGFS_HID_ATTRS="subclass protocol report_length report_desc wakeup_on_write"
+CONFIGFS_LUN_ATTRS="removable ro cdrom inquiry_string file"
+CONFIGFS_OS_DESC_ATTRS="use b_vendor_code qw_sign"
+CONFIGFS_RNDIS_ATTRS="class subclass protocol"
+CONFIGFS_RNDIS_OS_DESC_ATTRS="compatible_id sub_compatible_id"
+CONFIGFS_NCM_OS_DESC_ATTRS="compatible_id"
+
+cleanup(){
+    for dir in ${TMP_DIRS}
+    do
+        rm -rf "${dir}"
+    done
+}
+trap cleanup EXIT
+
+fail(){
+    echo "FAIL: $*" >&2
+    exit 1
+}
+
+assert_eq(){
+    [ "$1" = "$2" ] || fail "$3: got '$1', want '$2'"
+}
+
+assert_no_file(){
+    [ ! -e "$1" ] && [ ! -L "$1" ] || fail "unexpected file: $1"
+}
+
+assert_link(){
+    path="$1"
+    want="$2"
+    [ -e "${path}" ] || [ -L "${path}" ] || fail "missing file: ${path}"
+    got=$(readlink "${path}")
+    assert_eq "${got}" "${want}" "symlink ${path}"
+}
+
+assert_hex(){
+    assert_eq "$(od -An -tx1 -v "$1" | tr -d ' \n')" "$2" "hex $1"
+}
+
+hex_of(){
+    printf '%s' "$1" | od -An -tx1 -v | tr -d ' \n'
+}
+
+assert_text_bytes(){
+    assert_hex "$1" "$(hex_of "$2")"
+}
+
+USB_DEFAULT_UDC="4340000.usb"
+USB_PHY_DEVICE="4340000.usb"
+USB_SECONDARY_UDC="4350000.usb"
+USB_SERIAL_NUMBER="0123456789ABCDEF"
+USB_MANUFACTURER="sipeed"
+USB_PRODUCT="NanoKVM"
+USB_CONFIGURATION="NanoKVM"
+USB_NORMAL_BCD_USB="0x0200"
+USB_NORMAL_BCD_DEVICE="0x0510"
+USB_HID_ONLY_BCD_USB="0x0110"
+USB_HID_ONLY_BCD_DEVICE="0x0623"
+USB_HID_ONLY_CONFIG_ATTRIBUTES="0xA0"
+USB_HID_KEYBOARD_FUNC="hid.GS0"
+USB_HID_RELATIVE_MOUSE_FUNC="hid.GS1"
+USB_HID_ABSOLUTE_MOUSE_FUNC="hid.GS2"
+USB_MASS_STORAGE_FUNC="mass_storage.disk0"
+USB_RNDIS_FUNC="rndis.usb0"
+USB_NCM_FUNC="ncm.usb0"
+USB_LEGACY_EMPTY_DISK_BACKING="/dev/mmcblk0p3"
+USB_TEST_IMAGE="/data/install.iso"
+
+KEYBOARD_REPORT_DESC="05010906a101050719e029e71500250175019508810295017508810395057501050819012905910295017503910395067508150025e70507190029e78100c0"
+HID_ONLY_KEYBOARD_REPORT_DESC="05010906a101050719e029e71500250175019508810295017508810395057501050819012905910295017503910395067508150025650507190029658100c0"
+RELATIVE_MOUSE_REPORT_DESC="05010902a1010901a1000509190129031500250195037501810295017505810305010930093109381581257f750895038106c0c0"
+ABSOLUTE_MOUSE_REPORT_DESC="05010902a1010901a10005091901290515002501950575018102950175038101050109300931150026ff7f350046ff7f751095028102050109381581257f35004500750895018106c0c0"
+HID_ONLY_ABSOLUTE_MOUSE_REPORT_DESC="05010902a1010901a10005091901290315002501950375018102950175058101050109300931150026ff7f350046ff7f751095028102050109381581257f35004500750895018106c0c0"
+
+setup_fake_configfs_tools(){
+    base=$(mktemp -d)
+    TMP_DIRS="${TMP_DIRS} ${base}"
+    fake_bin="${base}/bin"
+    mkdir -p "${fake_bin}"
+
+    real_mkdir=$(command -v mkdir)
+    real_rmdir=$(command -v rmdir)
+
+    cat > "${fake_bin}/mkdir" <<EOF
+#!/bin/sh
+"${real_mkdir}" "\$@" || exit \$?
+touch_attrs(){
+    dir="\$1"
+    shift
+    for attr in "\$@"
+    do
+        touch "\${dir}/\${attr}"
+    done
+}
+prepare_fake_configfs_dir(){
+    dir="\$1"
+    case "\${dir}" in
+      g0|*/g0)
+        "${real_mkdir}" -p "\${dir}/strings" "\${dir}/configs" "\${dir}/functions" "\${dir}/os_desc"
+        touch_attrs "\${dir}" ${CONFIGFS_GADGET_ATTRS}
+        touch_attrs "\${dir}/os_desc" ${CONFIGFS_OS_DESC_ATTRS}
+        ;;
+      strings/0x409|*/strings/0x409)
+        touch_attrs "\${dir}" ${CONFIGFS_STRING_ATTRS}
+        ;;
+      configs/c.1|*/configs/c.1)
+        touch_attrs "\${dir}" ${CONFIGFS_CONFIG_ATTRS}
+        ;;
+      configs/c.1/strings/0x409|*/configs/c.1/strings/0x409)
+        touch_attrs "\${dir}" ${CONFIGFS_CONFIG_STRING_ATTRS}
+        ;;
+      functions/hid.GS*|*/functions/hid.GS*)
+        printf '%s' '0' > "\${dir}/subclass"
+        touch_attrs "\${dir}" ${CONFIGFS_HID_ATTRS}
+        ;;
+      functions/rndis.*|*/functions/rndis.*)
+        "${real_mkdir}" -p "\${dir}/os_desc/interface.rndis"
+        touch_attrs "\${dir}" ${CONFIGFS_RNDIS_ATTRS}
+        touch_attrs "\${dir}/os_desc/interface.rndis" ${CONFIGFS_RNDIS_OS_DESC_ATTRS}
+        ;;
+      functions/ncm.*|*/functions/ncm.*)
+        "${real_mkdir}" -p "\${dir}/os_desc/interface.ncm"
+        touch_attrs "\${dir}/os_desc/interface.ncm" ${CONFIGFS_NCM_OS_DESC_ATTRS}
+        ;;
+      functions/mass_storage.*/lun.0|*/functions/mass_storage.*/lun.0)
+        touch_attrs "\${dir}" ${CONFIGFS_LUN_ATTRS}
+        ;;
+      functions/mass_storage.*|*/functions/mass_storage.*)
+        "${real_mkdir}" -p "\${dir}/lun.0"
+        prepare_fake_configfs_dir "\${dir}/lun.0"
+        ;;
+    esac
+}
+for arg in "\$@"
+do
+    case "\${arg}" in
+      -*) ;;
+      *) [ -d "\${arg}" ] && prepare_fake_configfs_dir "\${arg}" ;;
+    esac
+done
+EOF
+
+    cat > "${fake_bin}/rmdir" <<EOF
+#!/bin/sh
+remove_fake_configfs_attrs(){
+    dir="\$1"
+    case "\${dir}" in
+      g0|*/g0)
+        rm -f "\${dir}/UDC" "\${dir}/bcdUSB" "\${dir}/bcdDevice" "\${dir}/idVendor" "\${dir}/idProduct" "\${dir}/bDeviceClass" "\${dir}/bDeviceSubClass" "\${dir}/bDeviceProtocol"
+        ;;
+      strings/0x409|*/strings/0x409)
+        rm -f "\${dir}/serialnumber" "\${dir}/manufacturer" "\${dir}/product"
+        ;;
+      configs/c.1|*/configs/c.1)
+        rm -f "\${dir}/bmAttributes" "\${dir}/MaxPower"
+        ;;
+      configs/c.1/strings/0x409|*/configs/c.1/strings/0x409)
+        rm -f "\${dir}/configuration"
+        ;;
+      functions/hid.GS*|*/functions/hid.GS*)
+        rm -f "\${dir}/subclass" "\${dir}/protocol" "\${dir}/report_length" "\${dir}/report_desc" "\${dir}/wakeup_on_write"
+        ;;
+      functions/mass_storage.*/lun.0|*/functions/mass_storage.*/lun.0)
+        rm -f "\${dir}/removable" "\${dir}/ro" "\${dir}/cdrom" "\${dir}/inquiry_string" "\${dir}/file"
+        ;;
+    esac
+}
+for arg in "\$@"
+do
+    case "\${arg}" in
+      -*) ;;
+      *)
+        [ -d "\${arg}" ] && remove_fake_configfs_attrs "\${arg}"
+        case "\${arg}" in
+          g0|*/g0)
+            [ ! -L "\${arg}/os_desc/c.1" ] || exit 1
+            rm -rf "\${arg}"
+            exit 0
+            ;;
+        esac
+        ;;
+    esac
+done
+"${real_rmdir}" "\$@"
+EOF
+
+    chmod +x "${fake_bin}/mkdir" "${fake_bin}/rmdir"
+
+    TEST_COMMON_SCRIPT="${base}/S03usb-common"
+    awk -v fake_bin="${fake_bin}" '
+        /^PATH=/ {
+            print "PATH=\"" fake_bin ":/sbin:/usr/sbin:/bin:/usr/bin${PATH:+:${PATH}}\""
+            next
+        }
+        { print }
+    ' "${COMMON_SCRIPT}" > "${TEST_COMMON_SCRIPT}"
+}
+
+assert_hid_attr(){
+    assert_eq "$(cat "$1/functions/$2/$3")" "$4" "$5"
+}
+
+assert_hid_boot_interfaces(){
+    g="$1"
+    label="$2"
+    assert_hid_attr "${g}" "${USB_HID_KEYBOARD_FUNC}" subclass 1 "${label} keyboard boot subclass"
+    assert_hid_attr "${g}" "${USB_HID_KEYBOARD_FUNC}" protocol 1 "${label} keyboard protocol"
+    assert_hid_attr "${g}" "${USB_HID_RELATIVE_MOUSE_FUNC}" subclass 1 "${label} mouse boot subclass"
+    assert_hid_attr "${g}" "${USB_HID_RELATIVE_MOUSE_FUNC}" protocol 2 "${label} mouse protocol"
+    assert_hid_attr "${g}" "${USB_HID_ABSOLUTE_MOUSE_FUNC}" subclass 0 "${label} touch non-boot subclass"
+    assert_hid_attr "${g}" "${USB_HID_ABSOLUTE_MOUSE_FUNC}" protocol 2 "${label} touch protocol"
+}
+
+assert_hid_function(){
+    assert_link "$1/configs/c.1/$2" "functions/$2"
+    assert_hid_attr "$1" "$2" subclass "$4" "$3 subclass"
+    assert_hid_attr "$1" "$2" protocol "$5" "$3 protocol"
+    assert_hid_attr "$1" "$2" report_length "$6" "$3 report length"
+    assert_hex "$1/functions/$2/report_desc" "$7"
+    assert_hid_attr "$1" "$2" wakeup_on_write "$8" "$3 wake"
+}
+
+assert_hid_functions(){
+    assert_hid_function "$1" "${USB_HID_KEYBOARD_FUNC}" "$2 keyboard" 1 1 8 "$3" "$5"
+    assert_hid_function "$1" "${USB_HID_RELATIVE_MOUSE_FUNC}" "$2 mouse" 1 2 4 "${RELATIVE_MOUSE_REPORT_DESC}" "$5"
+    assert_hid_function "$1" "${USB_HID_ABSOLUTE_MOUSE_FUNC}" "$2 touch" 0 2 6 "$4" "$5"
+}
+
+assert_normal_composite_descriptors(){
+    g="$1"
+    label="$2"
+    assert_eq "$(cat "${g}/bDeviceClass")" "0xEF" "${label} device class"
+    assert_eq "$(cat "${g}/bDeviceSubClass")" "0x02" "${label} device subclass"
+    assert_eq "$(cat "${g}/bDeviceProtocol")" "0x01" "${label} device protocol"
+}
+
+assert_os_descriptors(){
+    g="$1"
+    label="$2"
+    assert_link "${g}/os_desc/c.1" "configs/c.1"
+    assert_eq "$(cat "${g}/os_desc/use")" "1" "${label} OS descriptor enabled"
+    assert_eq "$(cat "${g}/os_desc/b_vendor_code")" "0xCD" "${label} vendor code"
+    assert_eq "$(cat "${g}/os_desc/qw_sign")" "MSFT100" "${label} OS descriptor signature"
+}
+
+assert_rndis_function(){
+    g="$1"
+    label="$2"
+    assert_link "${g}/configs/c.1/${USB_RNDIS_FUNC}" "functions/${USB_RNDIS_FUNC}"
+    assert_eq "$(cat "${g}/functions/${USB_RNDIS_FUNC}/class")" "e0" "${label} RNDIS class"
+    assert_eq "$(cat "${g}/functions/${USB_RNDIS_FUNC}/subclass")" "01" "${label} RNDIS subclass"
+    assert_eq "$(cat "${g}/functions/${USB_RNDIS_FUNC}/protocol")" "03" "${label} RNDIS protocol"
+    assert_eq "$(cat "${g}/functions/${USB_RNDIS_FUNC}/os_desc/interface.rndis/compatible_id")" "RNDIS" "${label} RNDIS compatible id"
+    assert_eq "$(cat "${g}/functions/${USB_RNDIS_FUNC}/os_desc/interface.rndis/sub_compatible_id")" "5162001" "${label} RNDIS sub-compatible id"
+}
+
+assert_no_hid_functions(){
+    g="$1"
+    for func in "${USB_HID_KEYBOARD_FUNC}" "${USB_HID_RELATIVE_MOUSE_FUNC}" "${USB_HID_ABSOLUTE_MOUSE_FUNC}"
+    do
+        assert_no_file "${g}/configs/c.1/${func}"
+        assert_no_file "${g}/functions/${func}"
+    done
+}
+
+new_env(){
+    base=$(mktemp -d)
+    TMP_DIRS="${TMP_DIRS} ${base}"
+    mkdir -p "${base}/boot" "${base}/dwc2" "${base}/gadget" "${base}/udc" "${base}/proc/cviusb"
+    touch "${base}/dwc2/bind" "${base}/dwc2/unbind"
+    touch "${base}/udc/${USB_DEFAULT_UDC}"
+    touch "${base}/proc/cviusb/otg_role"
+    echo "${base}"
+}
+
+run_script_action(){
+    script="$1"
+    action="$2"
+    base="$3"
+    USB_COMMON="${TEST_COMMON_SCRIPT}" \
+    USB_BOOT_DIR="${base}/boot" \
+    USB_GADGET_ROOT="${base}/gadget" \
+    USB_UDC_CLASS="${base}/udc" \
+    USB_OTG_ROLE="${base}/proc/cviusb/otg_role" \
+    USB_PHY_DEVICE="${USB_PHY_DEVICE}" \
+    USB_DWC2_BIND="${base}/dwc2/bind" \
+    USB_DWC2_UNBIND="${base}/dwc2/unbind" \
+    sh "${script}" "${action}" >/dev/null
+}
+
+run_start(){
+    script="$1"
+    base="$2"
+    run_script_action "${script}" start "${base}"
+}
+
+test_normal_hid_descriptors(){
+    base=$(new_env)
+    run_start "${NORMAL_SCRIPT}" "${base}"
+    g="${base}/gadget/g0"
+
+    assert_eq "$(cat "${g}/bcdUSB")" "${USB_NORMAL_BCD_USB}" "normal bcdUSB"
+    assert_eq "$(cat "${g}/bcdDevice")" "${USB_NORMAL_BCD_DEVICE}" "normal bcdDevice"
+    assert_normal_composite_descriptors "${g}" normal
+    assert_text_bytes "${g}/strings/0x409/manufacturer" "${USB_MANUFACTURER}"
+    assert_text_bytes "${g}/strings/0x409/product" "${USB_PRODUCT}"
+    assert_text_bytes "${g}/strings/0x409/serialnumber" "${USB_SERIAL_NUMBER}"
+    assert_text_bytes "${g}/configs/c.1/strings/0x409/configuration" "${USB_CONFIGURATION}"
+
+    assert_hid_functions "${g}" normal "${KEYBOARD_REPORT_DESC}" "${ABSOLUTE_MOUSE_REPORT_DESC}" 1
+    assert_eq "$(cat "${g}/UDC")" "${USB_DEFAULT_UDC}" "normal UDC"
+    assert_eq "$(cat "${base}/proc/cviusb/otg_role")" "device" "normal OTG role"
+}
+
+test_normal_bios_flag_keeps_only_boot_hid_interfaces(){
+    base=$(new_env)
+    touch "${base}/boot/BIOS"
+    run_start "${NORMAL_SCRIPT}" "${base}"
+    g="${base}/gadget/g0"
+
+    assert_hid_boot_interfaces "${g}" BIOS
+}
+
+test_normal_disable_hid_removes_hid_functions(){
+    base=$(new_env)
+    touch "${base}/boot/disable_hid"
+    run_start "${NORMAL_SCRIPT}" "${base}"
+    g="${base}/gadget/g0"
+
+    assert_no_hid_functions "${g}"
+}
+
+test_normal_legacy_mass_storage(){
+    base=$(new_env)
+    : > "${base}/boot/usb.disk0"
+    run_start "${NORMAL_SCRIPT}" "${base}"
+    g="${base}/gadget/g0"
+
+    assert_link "${g}/configs/c.1/${USB_MASS_STORAGE_FUNC}" "functions/${USB_MASS_STORAGE_FUNC}"
+    assert_eq "$(cat "${g}/functions/${USB_MASS_STORAGE_FUNC}/lun.0/removable")" "1" "mass storage removable"
+    assert_eq "$(cat "${g}/functions/${USB_MASS_STORAGE_FUNC}/lun.0/file")" "${USB_LEGACY_EMPTY_DISK_BACKING}" "legacy empty disk backing"
+}
+
+test_normal_mounted_image_and_network(){
+    base=$(new_env)
+    printf '%s' "${USB_TEST_IMAGE}" > "${base}/boot/usb.disk0"
+    touch "${base}/boot/usb.disk0.ro"
+    touch "${base}/boot/usb.rndis0"
+    run_start "${NORMAL_SCRIPT}" "${base}"
+    g="${base}/gadget/g0"
+
+    assert_normal_composite_descriptors "${g}" normal-network
+    assert_rndis_function "${g}" normal-network
+    assert_os_descriptors "${g}" normal-network
+    assert_eq "$(cat "${g}/functions/${USB_MASS_STORAGE_FUNC}/lun.0/file")" "${USB_TEST_IMAGE}" "mounted image"
+    assert_eq "$(cat "${g}/functions/${USB_MASS_STORAGE_FUNC}/lun.0/ro")" "1" "media ro flag"
+    assert_eq "$(cat "${g}/functions/${USB_MASS_STORAGE_FUNC}/lun.0/cdrom")" "0" "media cdrom flag"
+}
+
+test_network_restart_removes_os_desc_link(){
+    base=$(new_env)
+    touch "${base}/boot/usb.rndis0"
+    run_start "${NORMAL_SCRIPT}" "${base}"
+    run_start "${NORMAL_SCRIPT}" "${base}"
+    g="${base}/gadget/g0"
+
+    assert_os_descriptors "${g}" network-restart
+    assert_rndis_function "${g}" network-restart
+    assert_hid_functions "${g}" network-restart "${KEYBOARD_REPORT_DESC}" "${ABSOLUTE_MOUSE_REPORT_DESC}" 1
+}
+
+test_ncm_network_descriptors(){
+    base=$(new_env)
+    touch "${base}/boot/usb.ncm"
+    touch "${base}/boot/usb.rndis0"
+    run_start "${NORMAL_SCRIPT}" "${base}"
+    g="${base}/gadget/g0"
+
+    assert_link "${g}/configs/c.1/${USB_NCM_FUNC}" "functions/${USB_NCM_FUNC}"
+    assert_no_file "${g}/configs/c.1/${USB_RNDIS_FUNC}"
+    assert_eq "$(cat "${g}/functions/${USB_NCM_FUNC}/os_desc/interface.ncm/compatible_id")" "WINNCM" "NCM compatible id"
+    assert_normal_composite_descriptors "${g}" ncm
+    assert_os_descriptors "${g}" ncm
+}
+
+test_mode_switches_rebuild_gadget_contents(){
+    base=$(new_env)
+    touch "${base}/boot/usb.disk0"
+    touch "${base}/boot/usb.rndis0"
+
+    run_start "${NORMAL_SCRIPT}" "${base}"
+    g="${base}/gadget/g0"
+    assert_eq "$(cat "${g}/bcdDevice")" "${USB_NORMAL_BCD_DEVICE}" "normal mode bcdDevice"
+    assert_link "${g}/configs/c.1/${USB_MASS_STORAGE_FUNC}" "functions/${USB_MASS_STORAGE_FUNC}"
+    assert_rndis_function "${g}" mode-switch-normal
+    assert_os_descriptors "${g}" mode-switch-normal
+
+    run_start "${HID_ONLY_SCRIPT}" "${base}"
+    g="${base}/gadget/g0"
+    assert_eq "$(cat "${g}/bcdDevice")" "${USB_HID_ONLY_BCD_DEVICE}" "hid-only mode bcdDevice"
+    assert_eq "$(cat "${g}/bDeviceClass")" "" "hid-only device class"
+    assert_eq "$(cat "${g}/bDeviceSubClass")" "" "hid-only device subclass"
+    assert_eq "$(cat "${g}/bDeviceProtocol")" "" "hid-only device protocol"
+    assert_hid_functions "${g}" switched-hid-only "${HID_ONLY_KEYBOARD_REPORT_DESC}" "${HID_ONLY_ABSOLUTE_MOUSE_REPORT_DESC}" 1
+    assert_no_file "${g}/configs/c.1/${USB_MASS_STORAGE_FUNC}"
+    assert_no_file "${g}/configs/c.1/${USB_RNDIS_FUNC}"
+    assert_no_file "${g}/os_desc/c.1"
+
+    run_start "${NORMAL_SCRIPT}" "${base}"
+    g="${base}/gadget/g0"
+    assert_eq "$(cat "${g}/bcdDevice")" "${USB_NORMAL_BCD_DEVICE}" "switched-back normal bcdDevice"
+    assert_normal_composite_descriptors "${g}" switched-normal
+    assert_hid_functions "${g}" switched-normal "${KEYBOARD_REPORT_DESC}" "${ABSOLUTE_MOUSE_REPORT_DESC}" 1
+    assert_link "${g}/configs/c.1/${USB_MASS_STORAGE_FUNC}" "functions/${USB_MASS_STORAGE_FUNC}"
+    assert_rndis_function "${g}" switched-normal
+    assert_os_descriptors "${g}" switched-normal
+}
+
+test_hid_only_descriptors_and_no_wake(){
+    base=$(new_env)
+    touch "${base}/boot/usb.notwakeup"
+    touch "${base}/boot/usb.disk0"
+    touch "${base}/boot/usb.rndis0"
+    run_start "${HID_ONLY_SCRIPT}" "${base}"
+    g="${base}/gadget/g0"
+
+    assert_eq "$(cat "${g}/bcdUSB")" "${USB_HID_ONLY_BCD_USB}" "hid-only bcdUSB"
+    assert_eq "$(cat "${g}/bcdDevice")" "${USB_HID_ONLY_BCD_DEVICE}" "hid-only bcdDevice"
+    assert_eq "$(cat "${g}/configs/c.1/bmAttributes")" "${USB_HID_ONLY_CONFIG_ATTRIBUTES}" "hid-only bmAttributes"
+    assert_text_bytes "${g}/strings/0x409/serialnumber" "${USB_SERIAL_NUMBER}"
+    assert_text_bytes "${g}/strings/0x409/manufacturer" "${USB_MANUFACTURER}"
+    assert_text_bytes "${g}/strings/0x409/product" "${USB_PRODUCT}"
+    assert_text_bytes "${g}/configs/c.1/strings/0x409/configuration" "${USB_CONFIGURATION}"
+    assert_hid_functions "${g}" hid-only "${HID_ONLY_KEYBOARD_REPORT_DESC}" "${HID_ONLY_ABSOLUTE_MOUSE_REPORT_DESC}" ""
+    assert_no_file "${g}/configs/c.1/${USB_MASS_STORAGE_FUNC}"
+    assert_no_file "${g}/configs/c.1/${USB_RNDIS_FUNC}"
+}
+
+test_uses_one_udc(){
+    base=$(new_env)
+    touch "${base}/udc/${USB_SECONDARY_UDC}"
+    run_start "${NORMAL_SCRIPT}" "${base}"
+
+    assert_eq "$(cat "${base}/gadget/g0/UDC")" "${USB_DEFAULT_UDC}" "first UDC selected"
+}
+
+test_stop_unbinds_and_sets_host_role(){
+    base=$(new_env)
+    run_start "${NORMAL_SCRIPT}" "${base}"
+    run_script_action "${NORMAL_SCRIPT}" stop "${base}"
+
+    assert_eq "$(cat "${base}/gadget/g0/UDC")" "" "stopped UDC"
+    assert_eq "$(cat "${base}/proc/cviusb/otg_role")" "host" "stopped OTG role"
+}
+
+test_stop_then_start_rebuilds_gadget(){
+    base=$(new_env)
+    run_start "${NORMAL_SCRIPT}" "${base}"
+    run_script_action "${NORMAL_SCRIPT}" stop "${base}"
+    run_script_action "${NORMAL_SCRIPT}" start "${base}"
+    g="${base}/gadget/g0"
+
+    assert_eq "$(cat "${g}/UDC")" "${USB_DEFAULT_UDC}" "stop-start UDC"
+    assert_eq "$(cat "${base}/proc/cviusb/otg_role")" "device" "stop-start OTG role"
+    assert_hid_functions "${g}" stop-start "${KEYBOARD_REPORT_DESC}" "${ABSOLUTE_MOUSE_REPORT_DESC}" 1
+}
+
+test_restart_phy_rebuilds_gadget(){
+    base=$(new_env)
+    run_start "${NORMAL_SCRIPT}" "${base}"
+    run_script_action "${NORMAL_SCRIPT}" restart_phy "${base}"
+    g="${base}/gadget/g0"
+
+    assert_eq "$(cat "${base}/dwc2/unbind")" "${USB_PHY_DEVICE}" "phy unbind"
+    assert_eq "$(cat "${base}/dwc2/bind")" "${USB_PHY_DEVICE}" "phy bind"
+    assert_eq "$(cat "${g}/UDC")" "${USB_DEFAULT_UDC}" "restart-phy UDC"
+    assert_eq "$(cat "${base}/proc/cviusb/otg_role")" "device" "restart-phy OTG role"
+    assert_hid_functions "${g}" restart-phy "${KEYBOARD_REPORT_DESC}" "${ABSOLUTE_MOUSE_REPORT_DESC}" 1
+}
+
+test_restart_rebinds_udc(){
+    base=$(new_env)
+    run_start "${NORMAL_SCRIPT}" "${base}"
+    run_script_action "${NORMAL_SCRIPT}" restart "${base}"
+
+    assert_eq "$(cat "${base}/gadget/g0/UDC")" "${USB_DEFAULT_UDC}" "restarted UDC"
+}
+
+setup_fake_configfs_tools
+test_normal_hid_descriptors
+test_normal_bios_flag_keeps_only_boot_hid_interfaces
+test_normal_disable_hid_removes_hid_functions
+test_normal_legacy_mass_storage
+test_normal_mounted_image_and_network
+test_network_restart_removes_os_desc_link
+test_ncm_network_descriptors
+test_mode_switches_rebuild_gadget_contents
+test_hid_only_descriptors_and_no_wake
+test_uses_one_udc
+test_stop_unbinds_and_sets_host_role
+test_stop_then_start_rebuilds_gadget
+test_restart_phy_rebuilds_gadget
+test_restart_rebinds_udc
+
+echo "usb init script tests passed"