udevルールが私を狂わせる

私はこのusb-serialデバイスを持っています：

root@imx6_armboard:/etc/udev/rules.d# udevadm info -a -p $(udevadm info -q path -n /dev/ttyUSB0)

Udevadm info starts with the device specified by the devpath and then
walks up the chain of parent devices. It prints for every device
found, all possible attributes in the udev rules key format.
A rule to match, can be composed by the attributes of the device
and the attributes from one single parent device.

  looking at device '/devices/platform/fsl-ehci.1/usb2/2-1/2-1.1/2-1.1:1.0/ttyUSB0/tty/ttyUSB0':
    KERNEL=="ttyUSB0"
    SUBSYSTEM=="tty"
    DRIVER==""

  looking at parent device '/devices/platform/fsl-ehci.1/usb2/2-1/2-1.1/2-1.1:1.0/ttyUSB0':
    KERNELS=="ttyUSB0"
    SUBSYSTEMS=="usb-serial"
    DRIVERS=="ftdi_sio"
    ATTRS{latency_timer}=="1"
    ATTRS{port_number}=="0"

  looking at parent device '/devices/platform/fsl-ehci.1/usb2/2-1/2-1.1/2-1.1:1.0':
    KERNELS=="2-1.1:1.0"
    SUBSYSTEMS=="usb"
    DRIVERS=="ftdi_sio"
    ATTRS{bInterfaceNumber}=="00"
    ATTRS{bAlternateSetting}==" 0"
    ATTRS{bNumEndpoints}=="02"
    ATTRS{bInterfaceClass}=="ff"
    ATTRS{bInterfaceSubClass}=="ff"
    ATTRS{bInterfaceProtocol}=="ff"
    ATTRS{supports_autosuspend}=="1"
    ATTRS{interface}=="FT232R USB UART"

  looking at parent device '/devices/platform/fsl-ehci.1/usb2/2-1/2-1.1':
    KERNELS=="2-1.1"
    SUBSYSTEMS=="usb"
    DRIVERS=="usb"
    ATTRS{configuration}==""
    ATTRS{bNumInterfaces}==" 1"
    ATTRS{bConfigurationValue}=="1"
    ATTRS{bmAttributes}=="a0"
    ATTRS{bMaxPower}==" 90mA"
    ATTRS{urbnum}=="30409"
    ATTRS{idVendor}=="0403"
    ATTRS{idProduct}=="6001"
    ATTRS{bcdDevice}=="0600"
    ATTRS{bDeviceClass}=="00"
    ATTRS{bDeviceSubClass}=="00"
    ATTRS{bDeviceProtocol}=="00"
    ATTRS{bNumConfigurations}=="1"
    ATTRS{bMaxPacketSize0}=="8"
    ATTRS{speed}=="12"
    ATTRS{busnum}=="2"
    ATTRS{devnum}=="9"
    ATTRS{devpath}=="1.1"
    ATTRS{version}==" 2.00"
    ATTRS{maxchild}=="0"
    ATTRS{quirks}=="0x0"
    ATTRS{avoid_reset_quirk}=="0"
    ATTRS{authorized}=="1"
    ATTRS{manufacturer}=="FTDI"
    ATTRS{product}=="FT232R USB UART"
    ATTRS{serial}=="A400CZBK"

  looking at parent device '/devices/platform/fsl-ehci.1/usb2/2-1':
    KERNELS=="2-1"
    SUBSYSTEMS=="usb"
    DRIVERS=="usb"
    ATTRS{configuration}==""
    ATTRS{bNumInterfaces}==" 1"
    ATTRS{bConfigurationValue}=="1"
    ATTRS{bmAttributes}=="e0"
    ATTRS{bMaxPower}=="  2mA"
    ATTRS{urbnum}=="15513"
    ATTRS{idVendor}=="0424"
    ATTRS{idProduct}=="2513"
    ATTRS{bcdDevice}=="0bb3"
    ATTRS{bDeviceClass}=="09"
    ATTRS{bDeviceSubClass}=="00"
    ATTRS{bDeviceProtocol}=="02"
    ATTRS{bNumConfigurations}=="1"
    ATTRS{bMaxPacketSize0}=="64"
    ATTRS{speed}=="480"
    ATTRS{busnum}=="2"
    ATTRS{devnum}=="2"
    ATTRS{devpath}=="1"
    ATTRS{version}==" 2.00"
    ATTRS{maxchild}=="3"
    ATTRS{quirks}=="0x0"
    ATTRS{avoid_reset_quirk}=="0"
    ATTRS{authorized}=="1"

  looking at parent device '/devices/platform/fsl-ehci.1/usb2':
    KERNELS=="usb2"
    SUBSYSTEMS=="usb"
    DRIVERS=="usb"
    ATTRS{configuration}==""
    ATTRS{bNumInterfaces}==" 1"
    ATTRS{bConfigurationValue}=="1"
    ATTRS{bmAttributes}=="e0"
    ATTRS{bMaxPower}=="  0mA"
    ATTRS{urbnum}=="48"
    ATTRS{idVendor}=="1d6b"
    ATTRS{idProduct}=="0002"
    ATTRS{bcdDevice}=="0300"
    ATTRS{bDeviceClass}=="09"
    ATTRS{bDeviceSubClass}=="00"
    ATTRS{bDeviceProtocol}=="01"
    ATTRS{bNumConfigurations}=="1"
    ATTRS{bMaxPacketSize0}=="64"
    ATTRS{speed}=="480"
    ATTRS{busnum}=="2"
    ATTRS{devnum}=="1"
    ATTRS{devpath}=="0"
    ATTRS{version}==" 2.00"
    ATTRS{maxchild}=="1"
    ATTRS{quirks}=="0x0"
    ATTRS{avoid_reset_quirk}=="0"
    ATTRS{authorized}=="1"
    ATTRS{manufacturer}=="Linux 3.0.35-02671-gb0836db ehci_hcd"
    ATTRS{product}=="Freescale On-Chip EHCI Host Controller"
    ATTRS{serial}=="fsl-ehci.1"
    ATTRS{authorized_default}=="1"

  looking at parent device '/devices/platform/fsl-ehci.1':
    KERNELS=="fsl-ehci.1"
    SUBSYSTEMS=="platform"
    DRIVERS=="fsl-ehci"

  looking at parent device '/devices/platform':
    KERNELS=="platform"
    SUBSYSTEMS==""
    DRIVERS=="

これに対するルールを作成してみました/etc/udev/rules.d/99-usbserial-sensors.rules。これ

SUBSYSTEM=="usb-serial", KERNEL=="ttyUSB?", ATTRS{serial}=="A400CZBK", SYMLINK+="sensO2"

私は一つを書いたみんなある日、ドキュメントを見て、デバッグモードで実行しても、ルールが期待どおりに機能しない理由を理解しようとudevdしました。udevadm

最終的に（その日）この規則が適用されました。

SUBSYSTEMS=="usb", KERNEL=="ttyUSB?", ATTRS{serial}=="A400CZBK", SYMLINK+="sensO2"

だから基本的に私はSUBSYSTEM句を使用しました。S====USB" SUBSYSTEM="usb-serial" の代わりに。

問題は、なぜそれが機能するのかです。なぜデーモンをusb-serialトリガーしないのですか？特に人々が???でとらえるudevようにそこにいる場合にはさらにそうです。udevadm info

ありがとう