On Wednesday, 22 March 2017 14:58:32 UTC+11, Jon Seymour wrote:
>
>
>
> On Wednesday, 22 March 2017 11:58:26 UTC+11, Jon Seymour wrote:
>>
>>
>>
>> On Wednesday, 22 March 2017 01:08:22 UTC+11, RobertCNelson wrote:
>>>
>>> On Mon, Mar 20, 2017 at 9:37 PM, Jon Seymour <[email protected]> 
>>> wrote: 
>>>
>>> > Can anyone help me understand why this isn't working as expected? 
>>>
>>> it's systemd that's doing the rename, in /boot/uEnv.txt, find the 
>>> "cmdline=coherent_pool=1M quiet" option and change it to: 
>>>
>>> cmdline="coherent_pool=1M net.ifnames=0 quiet" 
>>>
>>> Starting on Dec 9th 2016, we added the "net.ifnames=0" option by 
>>> default. 
>>>
>>> on your next reboot, it'll show up as eth1.. 
>>>
>>> Regards, 
>>>
>>>
>> Robert,
>>
>> Thanks for the suggestion. However, It doesn't seem to have helped:
>>
>> from dmesg output:
>>
>> [   21.314582] ax88179_178a 1-1:1.0 eth1: register 'ax88179_178a' at 
>> usb-musb-hdrc.1.auto-1, D-Link DUB-1312 USB 3.0 to Gigabit Ethernet 
>> Adapter, e4:6f:13:f3:df:43
>> [   21.316347] usbcore: registered new interface driver ax88179_178a
>> [   21.769915] omap-aes 53500000.aes: OMAP AES hw accel rev: 3.2
>> [   21.813675] omap-sham 53100000.sham: hw accel on OMAP rev 4.3
>> [   23.989152] asoc-simple-card sound: i2s-hifi <-> 48038000.mcasp 
>> mapping ok
>> [   24.099140] ax88179_178a 1-1:1.0 enxe46f13f3df43: renamed from eth1
>>
>> debian@beaglebone:~$ cat /proc/cmdline
>> console=ttyO0,115200n8 root=UUID=74cfcc82-bdc4-483a-bcbd-cce4ad70ba00 ro 
>> rootfstype=ext4 rootwait coherent_pool=1M net.ifnames=0 quiet
>>
>> Currently, I have a udev rule in place:
>>
>> SUBSYSTEM=="net", ACTION=="add", DRIVERS=="ax88179_178a", 
>> ATTR{dev_id}=="0x0", ATTR{type}=="1", KERNEL=="enx*", NAME="eth1"
>>
>> Although I have also tried it with no udev rule. I also don't have a 
>> systemd.link configuration in place.
>>
>> debian@beaglebone:~$ uname -a
>> Linux beaglebone 4.4.26-ti-r59 #4 SMP Wed Feb 22 00:13:46 UTC 2017 armv7l 
>> GNU/Linux
>>
>> The kernel is a kernel I built from the r59 tag with a slightly different 
>> UART driver configuration.
>>
>> jon.
>>
>>
> It turns out that the following command is sufficient to disable the 
> mangled interface names:
>
>      sudo ln -sf /dev/null /etc/udev/rules.d/80-net-setup-link.rules
>
> and, in fact, net.ifnames=0 didn't seem to have any effect one way or the 
> other.
>
> Also, with the shorter interface name, DHCP now works on the renamed 
> interface - I have a suspicion that it was failing previously because the 
> enxe46f13f3df43 was at the limit of a char array length in a structure 
> defined in dhclient and this ultimately caused a downstream issue in the 
> AF_PACKET handler within the implementation of the bind system call) 
> because of the lack of a trailing null - all a supposition, of course.
>
> jon
>

The reason net.ifnames=0 didn't work appears to be related to this 
issue: 
http://askubuntu.com/questions/811295/73-usb-net-by-mac-rules-issue-with-net-ifnames/895533#895533.

In particular, net.ifnames=0 works if and only 
if /lib/udev/rules.d/73-usb-net-by-mac.rules is changed so that:

    IMPORT{cmdline}="net.ifnames", ENV{net.ifnames}=="0", 
GOTO="usb_net_by_mac_end"

becomes:

    IMPORT{cmdline}="net.ifnames"
    ENV{net.ifnames}=="0", GOTO="usb_net_by_mac_end"

With respect to the DHCP errors, I found that dhclient fails immediately if 
the interface name is: enxe46f13f3df43:

Internet Systems Consortium DHCP Client 4.3.1

Copyright 2004-2014 Internet Systems Consortium.

All rights reserved.

For info, please visit https://www.isc.org/software/dhcp/


Bind socket to interface: No such device


If you think you have received this message due to a bug rather

than a configuration issue please read the section on submitting

bugs on either our web page at www.isc.org or in the README file

before submitting a bug.  These pages explain the proper

process and the information we find helpful for debugging..


exiting.

fails in a different way if the interface name is enxe46f13f3df4 


Internet Systems Consortium DHCP Client 4.3.1

Copyright 2004-2014 Internet Systems Consortium.

All rights reserved.

For info, please visit https://www.isc.org/software/dhcp/


Listening on LPF/enxe46f13f3df4/e4:6f:13:f3:df:43

Sending on   LPF/enxe46f13f3df4/e4:6f:13:f3:df:43

Sending on   Socket/fallback

DHCPDISCOVER on enxe46f13f3df4 to 255.255.255.255 port 67 interval 4

send_packet: No such device

dhclient.c:1966: Failed to send 300 byte long packet over enxe46f13f3df4 
interface.

DHCPDISCOVER on enxe46f13f3df4 to 255.255.255.255 port 67 interval 10

send_packet: No such device

dhclient.c:1966: Failed to send 300 byte long packet over enxe46f13f3df4 
interface.


and succeeds if the interfacename is enxe46f13f3df or shorter.


The apparent explanation is a short copy in dhclient when it attempts to 
bind a PF_PACKET socket with the AF_PACKET address type.

jon.

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