Minimal supported kernel version

[dtodor]

Is there a minimal Linux kernel version required for running the OTBR. We have one system in particular, which seems to have problems when shutting down the OTBR daemon. The kernel version is 3.4.11-rt19. When being stopped, the process enters the state D (Uninterruptible Sleep) and we see the following system logs:

<0>unregister_netdevice: waiting for wpan0 to become free. Usage count = 1
<0>unregister_netdevice: waiting for wpan0 to become free. Usage count = 1
<0>unregister_netdevice: waiting for wpan0 to become free. Usage count = 1
...

On another system with kernel 3.12.59, the issue is not present. Have you seen such a behaviour? Are you aware of any mandatory kernel patches that have to be included?

[dtodor]

Here are the logs when stopping the OTBR:

Aug  3 11:07:31 user.info otbr-agent[510]: 00:01:38.371 [I] MeshForwarder-: Received IPv6 UDP msg, len:91, chksum:cb66, ecn:no, from:0211fa931fa268db, sec:no, prio:net, rss:-37.0
Aug  3 11:07:31 user.info otbr-agent[510]: 00:01:38.371 [I] MeshForwarder-:     src:[fe80:0:0:0:11:fa93:1fa2:68db]:19788
Aug  3 11:07:31 user.info otbr-agent[510]: 00:01:38.371 [I] MeshForwarder-:     dst:[ff02:0:0:0:0:0:0:1]:19788
Aug  3 11:07:31 user.info otbr-agent[510]: 00:01:38.371 [I] Mle-----------: Receive Advertisement (fe80:0:0:0:11:fa93:1fa2:68db,0x3000)
Aug  3 11:07:33 user.info otbr-agent[510]: [INFO]-BA------: Stop Thread Border Agent
Aug  3 11:07:33 user.info otbr-agent[510]: [INFO]-ADPROXY-: Stopped
Aug  3 11:07:33 user.info otbr-agent[510]: [INFO]-DPROXY--: Stopped
Aug  3 11:07:33 user.info otbr-agent[510]: [INFO]-BA------: Unpublish meshcop service OpenThread BorderRouter #CF94._meshcop._udp.local
Aug  3 11:07:33 user.info otbr-agent[510]: [INFO]-MDNS----: Removing service OpenThread BorderRouter #CF94._meshcop._udp
Aug  3 11:07:33 user.info otbr-agent[510]: [INFO]-BA------: Result of unpublish meshcop service OpenThread BorderRouter #CF94._meshcop._udp.local: OK
Aug  3 11:07:33 user.warn otbr-agent[510]: dnssd_clientstub deliver_request: invalid DNSServiceRef 0xb6fef920 00000000 0000000B
Aug  3 11:07:33 user.warn otbr-agent[510]: [WARN]-MDNS----: Failed to send goodbye message for host 0211FA931FA268DB.local: Bad Reference
Aug  3 11:07:33 user.warn otbr-agent[510]: dnssd_clientstub DNSServiceRemoveRecord called with bad DNSServiceRef
Aug  3 11:07:33 user.notice otbr-agent[510]: 00:01:39.566 [N] Mle-----------: Role router -> detached
Aug  3 11:07:33 user.info otbr-agent[510]: 00:01:39.566 [I] Platform------: [netif] Removed multicast address ff02::2
Aug  3 11:07:33 user.info otbr-agent[510]: 00:01:39.567 [I] Platform------: [netif] Removed multicast address ff03::2
Aug  3 11:07:33 user.info otbr-agent[510]: 00:01:39.568 [I] Platform------: [netif] Removed multicast address ff33:40:fdaf:6006:c0ef:c93a:0:1
Aug  3 11:07:33 user.info otbr-agent[510]: 00:01:39.568 [I] Platform------: [netif] Removed multicast address ff32:40:fdaf:6006:c0ef:c93a:0:1
Aug  3 11:07:33 user.info otbr-agent[510]: 00:01:39.568 [I] Platform------: [netif] Sent request#10 to remove fdaf:6006:c0ef:c93a:0:ff:fe00:6800/64
Aug  3 11:07:33 user.info otbr-agent[510]: 00:01:39.568 [I] Platform------: [netif] Sent request#11 to remove fdaf:6006:c0ef:c93a:7793:6338:12a6:e4b3/64
Aug  3 11:07:33 user.notice otbr-agent[510]: 00:01:39.568 [N] Mle-----------: Role detached -> disabled
Aug  3 11:07:33 user.info otbr-agent[510]: 00:01:39.568 [I] DnssdServer---: stopped
Aug  3 11:07:33 user.info otbr-agent[510]: 00:01:39.569 [I] Platform------: [netif] Sent request#12 to remove fe80::ac89:e9ad:c3aa:cf94/64
Aug  3 11:07:33 user.info otbr-agent[510]: 00:01:39.569 [I] Platform------: [netif] Removed multicast address ff02::1
Aug  3 11:07:33 user.info otbr-agent[510]: 00:01:39.569 [I] Platform------: [netif] Removed multicast address ff03::1
Aug  3 11:07:33 user.info otbr-agent[510]: 00:01:39.569 [I] Platform------: [netif] Removed multicast address ff03::fc
Aug  3 11:07:33 user.warn otbr-agent[510]: 00:01:39.571 [W] Platform------: Error processing result: NoAddress
Aug  3 11:07:33 user.warn otbr-agent[510]: 00:01:39.571 [W] Platform------: Error waiting response: NoAddress
Aug  3 13:07:34 daemon.notice mDNSResponder: Default: mDNS_Execute: SendResponses didn't send all its responses; will try again in one second
Aug  3 13:07:35 daemon.notice mDNSResponder: Default: mDNS_Execute: SendResponses didn't send all its responses; will try again in one second
Aug  3 13:07:36 daemon.notice mDNSResponder: Default: mDNS_Execute: SendResponses didn't send all its responses; will try again in one second