OpenWRT / MyBookLive mounts

Installing and Using OpenWrt
1

Hello:

I was checking out settings on my MBL / OpenWRT and had a look at the mounted filesystems:

root@OpenWrt:~# mount -l
/dev/sda2 on / type ext4 (rw,noatime) [rootfs]
proc on /proc type proc (rw,nosuid,nodev,noexec,noatime)
sysfs on /sys type sysfs (rw,nosuid,nodev,noexec,noatime)
cgroup2 on /sys/fs/cgroup type cgroup2 (rw,nosuid,nodev,noexec,relatime,nsdelegate)
tmpfs on /tmp type tmpfs (rw,nosuid,nodev,noatime)
/dev/sda1 on /boot type ext4 (rw,noatime,errors=remount-ro)
tmpfs on /dev type tmpfs (rw,nosuid,relatime,size=512k,mode=755)
devpts on /dev/pts type devpts (rw,nosuid,noexec,relatime,mode=600,ptmxmode=000)
/dev/sda3 on /mnt/sda3 type ext4 (rw,relatime) [data]
debugfs on /sys/kernel/debug type debugfs (rw,noatime)
none on /sys/fs/bpf type bpf (rw,nosuid,nodev,noexec,noatime,mode=700)
root@OpenWrt:~#

I have some idea as to what is going on (more or less) but I don't have a clue as to this entry:

none on /sys/fs/bpf type bpf (rw,nosuid,nodev,noexec,noatime,mode=700)

none clearly implies that nothing is mounted at the /sys/fs/bpf mount point and mode=700 means it is owned by and only accessed by root, but ...
What is that file system and what is it used for within OpenWRT?

Best,

JHM

2

Hi pclinuxer.
The /sys/fs/bpf mount point in OpenWRT is used for the Berkeley Packet Filter (BPF) file system. BPF is a powerful in-kernel virtual machine which allows you the execution of user-defined programs in the kernel space. It is way to perform network packet filtering, monitoring, and manipulation.
You can use BPF with (for example) tcpdump.

3

Hello:
Thank you for the prompt reply.
Much appreciated.

Best,

JHM