Add experimental Xtensa targets.

[reitermarkus]

Sources:

https://github.com/MabezDev/rust-xtensa https://github.com/ctron/rust-esp-container

[reitermarkus]

bors try

[bors[bot]]

try

Build succeeded

• rust-embedded.cross

[marcelbuesing]

Is there some way to use this already while the PR has not been merged yet, e.g. using the custom Docker Image?

[reitermarkus]

bors try

[bors[bot]]

try

Build failed:

• conclusion

[reitermarkus]

bors try

[bors[bot]]

try

Build failed:

• conclusion

[reitermarkus]

bors try

[bors[bot]]

try

Build failed:

• conclusion

[svenstaro]

@reitermarkus can you rebase this?

[Alexhuszagh]

Looks great as long as the code is rebased, this would be an excellent addition.

[Alexhuszagh]

I think this might actually be perfect for https://github.com/cross-rs/cross-toolchains (~~currently private, but planning to make it public shortly~~), since these Xtensa targets don't have any formal support, and therefore builds might be quite slow, especially for CI. It is perfect though to have recipes that are pre-defined that are likely to work, which these targets fall into.

Update: the repository has been made public.

[Alexhuszagh]

I'm closing this since it should be implemented in cross-toolchains, since these are not supported targets, not even tier 3. However, an implementation of these for custom builds would be greatly appreciated.