BeagleBone Black Networking (wifi and/or wired)

[Christian Mauderer]

On 09/06/2019 04:24, Chris Johns wrote:
> On 8/6/19 1:45 am, Christian Mauderer wrote:
>> Note that basically all device tree files that I have found yet are forked from the Linux ones.
> 
> Yes, I understand this is the case.
> 
>> They are all GPL.
> 
> We need to work with these files and respect the license they are under. I think
> GPL DTS is OK if these files are not linked into an executable. I am not sure
> where you stand in relation to the GPL license if you link a GPL dtb into an
> executable. An overlay we create under a suitable license should be fine.

Normally the DTB isn't linked in but loaded by some bootloader from a
file system so I agree that it shouldn't affect the license of the blob.

> 
>> I think it was Sichen Zhao during 2017 GSoC who wanted to add some to the RTEMS repository and it has been rejected due to the license.
> 
> I remember and I still think the position discussed is fine.
> 
>> I don't really object to adding them somewhere.
> 
> What do we host and maintain? Do we need to host any of these files or should we
> have a tool to collect and/or generate the blobs we need.

Most likely for most device trees it would be best to just refer to some
external source. For example the Linux tree or the one in FreeBSD (which
is a fork of the one from Linux) or some extracted tree.

We maybe have some exceptions with custom dts files or we can provide
some small overlays in case we need something special.

> 
>> But we should think exactly about where we want that stuff.
> 
> Having a blob as a file in a system theoretically lets someone update it. The
> `dtc` compiler can generate the dts source from a blob so a user can recover the
> source, make a change, generate a blob, then return it back into a system if
> they wish too.

Yes and if it is compiled with -@ option of the dtc it can even be
extended with overlays. But due to the GPL we should also provide a
matching source archive if we provide binaries.

> 
> What about building the FDT blobs we need with the RSB? I know this will work on
> FreeBSD and I suspect Linux, MacOS has some issues with clang's cpp.

I think there are more and more BSPs that can use the FDT (especially
ones that use libbsd) so it would be a good thing if they can be build
by RSB.

But please also note that we shouldn't see RSB as the only source for
DTBs. It's not uncommon that there is already a DTB on a board that is
just used by our BSP. Either because it's some evaluation board with a
matching one programmed somewhere and loaded by the original U-Boot or
for some FPGA based BSPs the DTB can be generated by the FPGA tools.

Best regards

Christian

> 
> Chris
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