Re: Question about batman for ARM

[Sven Eckelmann <sven@narfation.org>]

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On Friday, 20 May 2022 08:18:45 CEST Charles Chien wrote:
> We’re currently trying to install batman-adv on an ARM platform but we
> ran into some issues and we would appreciate your help to answer our
> questions below:
> 
> Is the batman-adv module compatible with an ARM processor (Raspberry PI 4)?

There is not just an "ARM" processor. It is a family of various processors.

Anyway, it can be used easily on Raspberry Pi - just make sure that you use a 
good wifi device + driver (+firmware) which actually can communicate over 
IBSS/802.11s (without forwarding enabled) and has no (extreme low) peer limit. 
Unfortunately, you cannot take this for granted.

> I’m trying to install batman-adv onto an ARM Raspberry PI 4 with a
> Debian based Linux distribution (Pop OS). However, when I run
> “modprobe batman-adv”, it returns a FATAL error complaining that the
> module is not found in the “/lib/modules” directory. Where can I
> find/download the “.ko” for batman-adv for the ARM platform?

Ehrm, this is not how this works. You cannot just use a kernel module and hope 
that it works on all kernel (builds) available in the universe. This is also 
why we write following in each batman-adv release news entry: "As the kernel 
module always depends on the Linux kernel it is compiled against, it does not 
make sense to provide binaries on our website. As usual, you will find the 
signed tarballs in our download section:"

Either your distribution has to enable this module in their kernel build or 
you have to get their kernel headers (and build scripts) and then build it 
from scratch. And at least on the default Debian kernel, batman-adv is enabled 
since ages - so no idea why PopOS doesn't ship it

> And if I need to recompile the .ko file for ARM, is there an online
> repository where I can find the original source code for the
> batman-adv driver?

This is mentioned in multiple places on the website. Just to mention a few 
interesting pages:

* https://www.open-mesh.org/projects/open-mesh/wiki
* https://www.open-mesh.org/news/108
* https://www.open-mesh.org/projects/open-mesh/wiki/Download
* https://www.open-mesh.org/projects/open-mesh/wiki/UsingBatmanGit
* https://git.open-mesh.org/
  https://git.open-mesh.org/batman-adv.git
* https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/

Kind regards,
	Sven

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