RFC: Create a module for picolibc

[keith-packard]

Rather than depending on the toolchain, create a module for picolibc and build it along with Zephyr. This has a few hacks to make it work; I'm mostly curious if this seems like a reasonable direction for picolibc integration. I've set it up to just use 'meson' to configure and build picolibc for now.

Closes #44143

[carlescufi]

Thanks @keith-packard, would you mind creating an issue as described here so we can proceed with the creation of a mirror repo after a TSC vote?

[carlescufi]

Please ignore the "Manifest" job failure, that's a bug on the bot side.

[keith-packard]

ok, I'll try to hold this version stable long enough to get a couple of approvals so we can just get 'er merged. If you have any comments about changes that are required, if they're relatively minor, let's plan on doing minor PRs after the merge to fix things up instead of delaying the merge.

[andyross]

Cool by me, certainly. Nothing really impactful is happening in the Zephyr tree that I can see, mostly cleanup for existing weirdness.

[stephanosio]

LGTM

[enjiamai]

Hi @keith-packard, the commit of the picolibc repo seems like a incorrect reversion in the west.yml. It will cause west update failed. Could you please help on correcting it? thanks.

199     - name: picolibc
200       path: modules/lib/picolibc
201       revision: 4f8076520240192be284843a114c92853e29bbbc

I cannot find this commit: 4f8076520240192be284843a114c92853e29bbbc in https://github.com/zephyrproject-rtos/picolibc

[enjiamai]

Update: it works after 0984aed got merged. thanks. Please ignore below comments, thanks!

[keith-packard]

Update: it works after 0984aed got merged. thanks. Please ignore below comments, thanks!

Sorry for messing up the zephyr/picolibc repo -- looks like we've got a process in place now with the ability to FF the main branch.