Change group of the /dev/fb0 from "root" to "video" permanently on imx6 card

Originally Posted by rocq Great! Now verify that 113 is actually the group ID of the "video" group: cat /etc/group | grep video Secondly, I would recommend that you remove your own rule 99-permissions.rules since 50-udev-default.rules already applies the video group to /dev/fb0

Yes actually 113 is the video group id

I removed my own rule 99-permissions.rules
I restarted the system and i am having always root for gid

and when i run the command :

udevadm test `udevadm info -q path -n /dev/fb0`

I have:

root@TBX01:~ udevadm test `udevadm info -q path -n /dev/fb0`
run_command: calling: test
adm_test: version 181
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.

builtin_kmod_init: load module index
add_matching_files: unable to open '/etc/udev/rules.d': No such file or directory
add_matching_files: unable to open '/run/udev/rules.d': No such file or directory
parse_file: reading '/lib/udev/rules.d/50-udev-default.rules' as rules file
util_lookup_group: specified group 'audio' unknown
parse_file: reading '/lib/udev/rules.d/60-persistent-alsa.rules' as rules file
parse_file: reading '/lib/udev/rules.d/60-persistent-input.rules' as rules file
parse_file: reading '/lib/udev/rules.d/60-persistent-serial.rules' as rules file
parse_file: reading '/lib/udev/rules.d/60-persistent-storage-tape.rules' as rules file
parse_file: reading '/lib/udev/rules.d/60-persistent-storage.rules' as rules file
parse_file: reading '/lib/udev/rules.d/75-net-description.rules' as rules file
parse_file: reading '/lib/udev/rules.d/75-tty-description.rules' as rules file
parse_file: reading '/lib/udev/rules.d/78-sound-card.rules' as rules file
parse_file: reading '/lib/udev/rules.d/80-drivers.rules' as rules file
parse_file: reading '/lib/udev/rules.d/85-usb-drives-auto-mounting.rules' as rules file
parse_file: reading '/lib/udev/rules.d/95-keyboard-force-release.rules' as rules file
parse_file: reading '/lib/udev/rules.d/95-keymap.rules' as rules file
parse_file: reading '/lib/udev/rules.d/95-udev-late.rules' as rules file
parse_file: reading '/lib/udev/rules.d/99-systemd.rules' as rules file
parse_file: reading '/lib/udev/rules.d/99-usb-serial.rules' as rules file
udev_rules_new: rules use 16968 bytes tokens (1414 * 12 bytes), 12065 bytes buffer
udev_rules_new: temporary index used 11860 bytes (593 * 20 bytes)
udev_device_new_from_syspath: device 0x3a318 has devpath '/devices/platform/mxc_sdc_fb.0/graphics/fb0'
udev_device_new_from_syspath: device 0x3a470 has devpath '/devices/platform/mxc_sdc_fb.0/graphics/fb0'
udev_device_read_db: device 0x3a470 filled with db file data
udev_rules_apply_to_event: GROUP 113 /lib/udev/rules.d/50-udev-default.rules:38
udev_node_add: handling device node '/dev/fb0', devnum=c29:0, mode=0660, uid=0, gid=113
node_fixup: set permissions /dev/fb0, 020660, uid=0, gid=113
node_symlink: preserve already existing symlink '/dev/char/29:0' to '../fb0'
udev_device_update_db: created db file '/run/udev/data/c29:0' for '/devices/platform/mxc_sdc_fb.0/graphics/fb0'
ACTION=add
DEVNAME=/dev/fb0
DEVPATH=/devices/platform/mxc_sdc_fb.0/graphics/fb0
ID_USB_INTERFACE_NUM=
MAJOR=29
MINOR=0
SUBSYSTEM=graphics
UDEV_LOG=6
USEC_INITIALIZED=12967592
builtin_kmod_exit: unload module index


Any suggestion?

Are you running systemd? If yes, what's the output of commands 'systemctl status -l --no-pager -n 1000 systemd-udevd' and 'systemctl status -l --no-pager -n 1000 systemd-udev-trigger'?

any update mostefa?

Dear rocq

the output of the command:

systemctl status -l --no-pager -n 1000 systemd-udevd' and 'systemctl status -l --no-pager -n 1000 systemd-udev-trigger

is:
systemctl: invalid option -- 'l'


After debugging the startup of my embedded linux i found that in one startup script , i am having :

mdev -s

and according to the help , this command:

root:~ mdev --h
BusyBox v1.18.5 (2018-07-30 10:15:17 CEST) multi-call binary.

Usage: mdev [-s]

-s Scan /sys and populate /dev during system boot


So i think that the problem is that i am populating agin /dev and /sys after udev rules are applied.

I deleted this line , and for no , i am not having this problem anymore !

Thank you