Problems with udev rules

[espruino-discuss3]

Posted at 2016-08-18 by avanc

Hello,

I'm using the udev rules from here .
However, the group of /dev/ttyACM0 is not changed to pludev neither are the permissions changed.

udevadm test /dev/ttyACM0 gives the following:

[root@herrod ~]# udevadm test /dev/ttyACM0 
calling: test
version 231
This program is for debugging only, it does not run any program
specified by a RUN key. It may show incorrect results, because
some values may be different, or not available at a simulation run.

=== trie on-disk ===
tool version:          231
file size:         7291171 bytes
header size             80 bytes
strings            1819099 bytes
nodes              5471992 bytes
Load module index
Found container virtualization none
timestamp of '/etc/systemd/network' changed
timestamp of '/usr/lib/systemd/network' changed
Parsed configuration file /usr/lib/systemd/network/99-default.link
Created link configuration context.
timestamp of '/etc/udev/rules.d' changed
timestamp of '/usr/lib/udev/rules.d' changed
Reading rules file: /usr/lib/udev/rules.d/40-usb-media-players.rules
Reading rules file: /etc/udev/rules.d/45-espruino.rules
Reading rules file: /usr/lib/udev/rules.d/49-sane.rules
rules contain 393216 bytes tokens (32768 * 12 bytes), 32238 bytes strings
25863 strings (208413 bytes), 22554 de-duplicated (179485 bytes), 3310 trie nodes used
unable to open device '/sys/dev/ttyACM0'
Unload module index
Unloaded link configuration context.

I'm using Arch Linux.
Any idea why the group is not set?

[espruino-discuss3]

Posted at 2016-08-18 by @gfwilliams

Does arch linux have a plugdev group?

Maybe you could try restarting? It might be that the rules need reloading... I realise it's not in the Quick Start, but you can do udevadm control --reload-rules to force a reload without restarting.

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Posted at 2016-08-18 by avanc

Yes, the group pludev is available and I also use it for another device. Reboot and reload rules doesn't change anything. It seems that the rule is not triggered at all.

Maybe this is of help, /dev/ttyACM0 does not have productID nor vendorID. It is available one level below.

udevadm info -a -p $(udevadm info -q path -n /dev/ttyACM0)        

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/pci0000:00/0000:00:14.0/usb3/3-2/3-2:1.0/tty/ttyACM0':
    KERNEL=="ttyACM0"
    SUBSYSTEM=="tty"
    DRIVER==""

  looking at parent device '/devices/pci0000:00/0000:00:14.0/usb3/3-2/3-2:1.0':
    KERNELS=="3-2:1.0"
    SUBSYSTEMS=="usb"
    DRIVERS=="cdc_acm"
    ATTRS{authorized}=="1"
    ATTRS{bAlternateSetting}==" 0"
    ATTRS{bInterfaceClass}=="02"
    ATTRS{bInterfaceNumber}=="00"
    ATTRS{bInterfaceProtocol}=="01"
    ATTRS{bInterfaceSubClass}=="02"
    ATTRS{bNumEndpoints}=="01"
    ATTRS{bmCapabilities}=="2"
    ATTRS{supports_autosuspend}=="1"

  looking at parent device '/devices/pci0000:00/0000:00:14.0/usb3/3-2':
    KERNELS=="3-2"
    SUBSYSTEMS=="usb"
    DRIVERS=="usb"
    ATTRS{authorized}=="1"
    ATTRS{avoid_reset_quirk}=="0"
    ATTRS{bConfigurationValue}=="1"
    ATTRS{bDeviceClass}=="02"
    ATTRS{bDeviceProtocol}=="00"
    ATTRS{bDeviceSubClass}=="00"
    ATTRS{bMaxPacketSize0}=="64"
    ATTRS{bMaxPower}=="100mA"
    ATTRS{bNumConfigurations}=="1"
    ATTRS{bNumInterfaces}==" 2"
    ATTRS{bcdDevice}=="0200"
    ATTRS{bmAttributes}=="c0"
    ATTRS{busnum}=="3"
    ATTRS{configuration}==""
    ATTRS{devnum}=="4"
    ATTRS{devpath}=="2"
    ATTRS{idProduct}=="5740"
    ATTRS{idVendor}=="0483"
    ATTRS{ltm_capable}=="no"
    ATTRS{manufacturer}=="STMicroelectronics"
    ATTRS{maxchild}=="0"
    ATTRS{product}=="STM32 Virtual ComPort"
    ATTRS{quirks}=="0x0"
    ATTRS{removable}=="removable"
    ATTRS{serial}=="00000000001A"
    ATTRS{speed}=="12"
    ATTRS{urbnum}=="211"
    ATTRS{version}==" 2.00"
...

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Posted at 2016-08-18 by avanc

Even the following rule is not working:

KERNEL=="ttyACM0*", MODE="0666", GROUP="plugdev"

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Posted at 2016-08-19 by @gfwilliams

It might actually be worth looking at what they suggest for Arduino: https://wiki.archlinux.org/index.php/Arduino

Looks like adding your user to uucp and lock groups might be enough, without needing any udev

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Posted at 2016-08-21 by avanc

It's just that easy :-) Thanks.

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Posted at 2016-08-22 by @gfwilliams

Thanks for letting me know - I'll update the Quick Start guide