Makefile: Add nonfree repo to fix model fetching

[alex96295]

• As observed from July 15th, 2025, Infineon requires SSO authentication to download the hyperram model files. Therefore, our current way of fetching the model is broken
• For internal usage, this PR adds support to fetch the model from a cached location, or automatically downloading it, through the variable CACHED_MODEL, default to true.
• Open-source users must manually download the models with their credentials.
• nonfree reference PR: https://iis-git.ee.ethz.ch/pulp-restricted/hyperbus-nonfree/-/merge_requests/1

Note: the flow was successfully tested in-system in chimera: https://iis-git.ee.ethz.ch/github-mirror/chimera/-/pipelines

[phsauter]

I think we might want to remove the automatic download if /etc/iis.version exists. I see the intention but just because someone is on an iis machine doesn't mean they have access to the repo.

[alex96295]

I think we might want to remove the automatic download if /etc/iis.version exists. I see the intention but just because someone is on an iis machine doesn't mean they have access to the repo.

Good point, download will fail anyway if someone does not have access. I guess we can just leave the make hyperbus-nonfree-init call and then the command will fail if a IIS person does not have access

[alex96295]

I think we might want to remove the automatic download if /etc/iis.version exists. I see the intention but just because someone is on an iis machine doesn't mean they have access to the repo.

Good point, download will fail anyway if someone does not have access. I guess we can just leave the make hyperbus-nonfree-init call and then the command will fail if a IIS person does not have access

Errata corrige: we have to remove the whole hunk in ifneq [...] endif; however, note that this way systems integrating the hyperbus after this commit will have to manually download the nonfree and add it to the init job of their CIs; backward compatibilty suffers slightly, and a major release is required