upgrade tools to build core platform sdk

[malus-brandywine]

New intermediate image was added between "TS/sel4" image and "extras".

The sel4cp.dockerfile:
updates python packages, adds other necessary packages,
installs ARM cross-tools binaries 10.2-2020.11,
clones and builds the latest musl,
copies script cp_prep.sh into /tmp

Signed-off-by: Nataliya Korovkina [email protected]

[lsf37]

Hey @malus-brandywine, thanks for the PR. Unfortunately I think it's a bit too early.

In general, there should ideally not be a new build environment necessary for the CP (adding some python packages sure, but not new compiler versions, libraries etc). Simplifying the build is part of its main point, so the CP should change to work with the standard foundation build environment as defined in the docker files. Ideally that would be after #39 is merged, which should bring GCC up to date with what the CP also expects.

I think we should probably wait for more discussion after more people have evaluated it. In the meantime I think your PR will be helpful to those people even if we don't merge it yet.

More detailed issues for later:

• For LaTeX dependencies there should be an existing option we can use if more dependencies are needed.
• More generally, if we do add something like muslc to docker images, it needs to be reproducible and at least version tagged. The same docker build sequence must produce the same binary (this is why the images use snapshot dates for Debian by default).

There is of course the distinction between building the CP tools themselves and using the CP tools to build a system. The former may need a new docker image for CI in the end, the latter really shouldn't.

[malus-brandywine]

Thanks for the clarification, @lsf37 !

(At least I solved my local problem for now... )