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Vimer
Asked: 2024-09-20 16:48:04 +0800 CST

There are devices under /proc/tty/drivers, but not under /dev?

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I plugged a minipcie to 4-channel RS485 EMP2-X404 module into my PC, and there was an additional gpiochip1 under /dev/. I installed the driver provided by the manufacturer and I can see an additional xrserial in /proc/tty/drivers, but there is no /dev/ttyXR under /dev. What is the reason?

My system is Ubuntu 20.04 with kernel 6.1.0.

cat /proc/tty/drivers
/dev/tty             /dev/tty        5       0 system:/dev/tty
/dev/console         /dev/console    5       1 system:console
/dev/ptmx            /dev/ptmx       5       2 system
/dev/vc/0            /dev/vc/0       4       0 system:vtmaster
xrserial             /dev/ttyXR     30 0-255 serial
serial               /dev/ttyS       4 64-95 serial
pty_slave            /dev/pts      136 0-1048575 pty:slave
pty_master           /dev/ptm      128 0-1048575 pty:master
unknown              /dev/tty        4 1-63 console
drivers

1 Answers

  1. Best Answer

    If a device node has not been created automatically there's no need to worry about its absence. If future applications or system setups require the device node, it can always be created manually or configured as needed.

    You can try manually creating the device node by running sudo mknod /dev/ttyXR c <major_number> <minor_number>

    You can find the major and minor numbers from the results of cat /proc/tty/drivers. For xrserial the major number is 30, and the minor number typically starts from 0 as seen in this line of the output:

    xrserial             /dev/ttyXR     30        0-255 serial

    If this command doesn't work and your Ubuntu is working normally, there's no need to create an additional device node right now.

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