[RFC] Advice re auto-extroot for EcoNet platform

[Caleb James DeLisle]

>      > discussion. Furthermore, making all of the modules built-in has been shown to
>      > have a significant amount of space-savings (
>      > https://openwrt.org/docs/guide-user/additional-software/saving_space#making_all_kernel_modules_built-in
>      > ) so that flag might be worth something to others as well.
>
> Oh, so it's a overwall win by removing .ko files from the rootfs.

I just checked and in the econet configuration, setting every =m to =y 
saves 1328 bytes in the kernel+initramfs image.

On the TRX it costs 4 bytes, which is probably some padding issue.

>      > The second question is what is the right way to handle devices which have a
>      > small JFFS or UBI section in addition to the extroot? If it exists at the
>      > time the extroot is first mounted, we can copy files over, but if we boot
>      > with the extroot removed, data will be stored there again and it will go out
>      > of sync. We can imagine creating an init script which prints a warning in
>      > this case, but the risk will always be present. My preference, because
>      > I
>
> Panic, flash available LEDs?
> extroot seems like an "us" problem, not a user problem.
> Anyone likely to do it, is likely aware of this list.
> Sure, some of us might do this for someone else... hide the key with black tape.

Good point. For my use case, it's fine to do nothing, so I think I would 
prefer to make a PR with nothing, then wait for someone who has a use 
case where something should be done to update the code to do that. Same 
goes for other things like auto-installing additional packages after the 
extroot mounts, I don't think I need this right now, so I prefer not to 
try to implement something I imagine someone else might want.

Thanks,

Caleb

>
> {I have used USB keys that were barely bigger than the connector for white
> label router platforms that ran essentially from ram.  Customer then wanted
> RAID for the USB keys :-).  Customers also couldn't even see some of them, as
> some MBs have USB slots inside 1U}
>
>
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