mkresin:

Hey Pavel,

am I right that it worked for you back in the days? If yes, any chance that you do a git bisect to check which commit introduced the issue? I can not see something obvious wrong and don't have a ipq806x board to test it on my own.

hnyman:

It seems to have broken down in January 2017, before 22th.

I tested with my R7800 my archive of month-end builds, and:

MAC ok: r2708-39d3a4117b-20161230
random: r3064-f798776188-20170122
random: r3189-12db207e9b-20170128

I will look for suspicious changes between r2708 and r3064...

hnyman:

Looks like it is the commit 71a39b8

https://git.lede-project.org/?p=source.git;a=commitdiff;h=71a39b869019c97f48bc85d9a8fabceead217d07;hp=2a7f669016f2faa29d64a59252556b96a55d071a

Specifically the change to 10_fix_wifi_mac script.

I tested with a live R7800 running up-to-date r3285-1a52d11d38

• reverting commit 71a39b8 with "patch -R" fixed MACs
• applying the change for 11-ath10k-caldata still produced ok MAC
• applying the change for 10_fix_wifi_mac caused random MAC

Possibly some sneaky whitespace error, or such.

EDIT:
I found it:
extra TAB char after the backslash on the line with 7500v2
" r7500v2 |\ "
Deleting that tab fixes MACs

Line 19:
https://git.lede-project.org/?p=source.git;a=blob;f=target/linux/ipq806x/base-files/etc/hotplug.d/ieee80211/10_fix_wifi_mac;hb=HEAD#l19

mkresin:

Wow, I had never expected that a trailing tab can cause such issues. Hannu, would it be possible that you send a patch that references this bugreport.

hnyman:

Pull request submitted as
lede-project/source#777

Note that the patch is needed also for 17.01.

hnyman:

I had never expected that a trailing tab can cause such issues

That surprised also me, but it is actually perfectly logical (as then the TAB is the next char to be ignored, not the subsequent newline).

That seems to be also mentioned in some shell script resources:

For example:
http://linuxcommand.org/wss0060.php

Note that for this trick to work, the newline must be typed immediately after the backslash. If you put a space after the backslash, the space will be ignored, not the newline.