.serialno is the eMMC CID.
As you had mentioned earlier this post fix for bt mac address, similar for wlan also.
This is a temporary solution to ensure that each board gets a unique MAC address, provided by the bootloader. there is on going work to get rid of this hack and store MAc addresses in a persistent area on the eMMC
i just had an IRC discussion with the 96boards maintainer that cares for the dragonboard:
<ogra_> ndec, do you plan do do a similar fix as https://git.linaro.org/landing-teams/working/qualcomm/lk.git/commit/?h=release/LA.BR.1.2.7-03810-8x16.0&id=372982a4d4c4922e9214ff7d6aa5348aaba602a7 for the wlan address at some point (i'd really like t get rid of the initrd hack to feed /run/macaddr0 at some point)
<ndec> ogra_: hi! it's done for wlan already. it was done before the bt stuff actually.
<ndec> this commit is before the one you linked: https://git.linaro.org/landing-teams/working/qualcomm/lk.git/commit/?h=release/LA.BR.1.2.7-03810-8x16.0&id=d27b915da64b5e3bc2f672cc8757ce523bf1b89c
<ndec> and the driver already has support, https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/drivers/net/wireless/ath/wcn36xx/main.c#n1279
<ndec> ogra_: btw, these days, we are trying to define a 'provision' file that would contain the 'real' MAC addresses for wlan and bt.
<ndec> the provisioning would/could be done in production (or re-done by end users)
<ndec> no, the bootloader will read that 'provision info' and populate the DTB at run time
<ogra_> with no fallback to serial at all ?
<ndec> yes, with a fallback.
<ogra_> ah
<ndec> the thing is that the boards are being provisioned with real MAC address (Arrow bought them). and right now they are not being used
<ndec> QCOM already has a 'solution' for this problem in their Windows 10 image. we are trying to reuse their provisioning file format.
<ogra_> so what would happen if i dropped the /run/macaddr0 hack right now (assuming i have the lk and kernel patches indeed)
<ndec> ogra_: nothing would happen, it would just work ;-)
so in that light, expect the script in the initrd to go away soon … (but you should be able to use the mentioned “provision” file at some point, until then i’d still recommend using something like the mac-spoofer snap)
so we need to wait for this ‘provision’ file to have permanent solution