I currently try to get GPIO-access into an unprivileged LXC application container. In future this container shall execute an application. But for now (while development) I just start a normal bash in the container:
sudo lxc-execute -n gpio-client -f /var/proj/gpio-client/lxc.conf -- bin/bash
When I do this with a privileged container (means my lxc.conf doesn't contain any UID- or GID-mapping) I can use the GPIO's.
The GPIO's can be access over files in /sys/class/gpio (following output comes from a bash within a privileged container which was started with the command above):
bash-4.3# cd /sys/class/gpio/
bash-4.3# ls -l
total 0
-rwxrwx--- 1 gpio-cli 1001 4096 Feb 20 12:41 export
lrwxrwxrwx 1 gpio-cli 1001 0 Feb 20 12:41 gpiochip890 -> ../../devices/gpiochip2/gpio/gpiochip890
lrwxrwxrwx 1 gpio-cli 1001 0 Feb 20 12:41 gpiochip898 -> ../../devices/gpiochip1/gpio/gpiochip898
lrwxrwxrwx 1 gpio-cli 1001 0 Feb 20 12:41 gpiochip906 -> ../../devices/soc0/amba/e000a000.gpio/gpio/gpiochip906
-rwxrwx--- 1 gpio-cli 1001 4096 Feb 20 12:41 unexport
For example I am able to export a GPIO:
bash-4.3# echo 898 > export
bash-4.3# ls -l
total 0
-rwxrwx--- 1 gpio-cli 1001 4096 Feb 20 14:06 export
lrwxrwxrwx 1 gpio-cli 1001 0 Feb 20 14:06 gpio898 -> ../../devices/gpiochip1/gpio/gpio898
lrwxrwxrwx 1 gpio-cli 1001 0 Feb 20 12:41 gpiochip890 -> ../../devices/gpiochip2/gpio/gpiochip890
lrwxrwxrwx 1 gpio-cli 1001 0 Feb 20 12:41 gpiochip898 -> ../../devices/gpiochip1/gpio/gpiochip898
lrwxrwxrwx 1 gpio-cli 1001 0 Feb 20 12:41 gpiochip906 -> ../../devices/soc0/amba/e000a000.gpio/gpio/gpiochip906
-rwxrwx--- 1 gpio-cli 1001 4096 Feb 20 12:41 unexport
When I print the running processes on the host with "ps -a" I can see the running bash as root:
587 root 0:00 lxc-execute -n gpio-client -f /var/proj/gpio-client/lxc.conf -- bin/bash
598 root 0:00 /init.lxc.static -- bin/bash
615 root 0:00 bin/bash
But when I insert a UID- and GID-mapping into the lxc.conf (and also the subuids and subgids in /etc/subuid and /etc/subgid) I always get a "Permission denied" when I try to access /sys/class/gpio:
bash-4.3# cd /sys/class/
bash-4.3# ls -l
total 0
drwxrwx--- 2 65534 gpio 0 Feb 20 14:11 gpio
bash-4.3# cd gpio/
bash: cd: gpio/: Permission denied
This is my lxc.conf:
# *************************************************************************
# * general configuration
# *************************************************************************
# container name
lxc.utsname = gpio-client
# *************************************************************************
# * configure networking
# *************************************************************************
lxc.network.type = veth
lxc.network.flags = up
lxc.network.link = local_br0
lxc.network.name = lxcnet0
lxc.network.hwaddr = 4a:49:43:49:79:ac
lxc.network.ipv4 = 10.10.0.98
lxc.network.ipv4.gateway = 10.10.0.1
# *************************************************************************
# * configure container filesystem
# *************************************************************************
# set rootfs
lxc.rootfs = /var/proj/gpio-client/rootfs
# mount needed directories from host
lxc.mount.entry=/lib lib none ro,bind 0 0
lxc.mount.entry=/sys/class/gpio sys/class/gpio none rw,bind 0 0
lxc.mount.entry=/sys/devices sys/devices none rw,bind 0 0
lxc.mount.entry=/usr/lib usr/lib none ro,bind 0 0
lxc.mount.entry=/usr/bin usr/bin none ro,bind 0 0
lxc.mount.entry=/bin bin none ro,bind 0 0
# *************************************************************************
# * configure privileges of container
# *************************************************************************
# map user and group ids
lxc.include = /usr/share/lxc/config/userns.conf
# comment the following out for a privileged container:
lxc.id_map = u 0 1000000 65536
lxc.id_map = g 0 1000000 65536
This is the running linux-system:
zedboard-zynq7:/var/proj/gpio-client$ cat /proc/version
Linux version 4.6.0-rt1-xilinx-v2016.3 (sebastian@ubuntu1604vm) (gcc version 6.2.0 (GCC) ) #5 SMP PREEMPT RT Fri Apr 7 13:43:09 CEST 2017
The system was build using Yocto for a AVNET-Zedboard (which has a Xilinx Zynq-SoC).
Does anyone have an idea or advise how to get this running or where to find the solution/information for this? I tried to get it running for a couple of hours but unfortunately I didn't managed it...
Best regards
Sebastian
