I have had the opportunity to speak with Intel on this, through a client company – remember that Altera was bought out by Intel…
Oh, yes, the first story we got mentioned Spectre/Meltdown. Then their story morphed - after pointed questioning - though they still claim vulnerability as a contributing factor, but they refined their story a few weeks later:
Intel has a policy of not distributing unsupported sources. Their so-called ‘-ltsi’ branch will be abandoned every 12 months for a new one, as a matter of policy. All past branches no longer current will be deleted periodically. No History, No archives, after a few months it will be as if it never happened… After scraping our jaws off the floor, we decided they really don’t understand open-source… not at all.
I am no lawyer, but I think this is a violation of the GPL; but that is not really helpful to those of us trying to build with instructions from others which reference the linux-socfpga repo Altera used to maintain.
If you have a local repo, you need to ensure it is totally safe… If you don’t want to play musical support with Intel, that is your only real choice. You would need to adjust your SRC_URI to use your local repo.
If YOU have a product, then you need to decide how to make your GPL sources available now that Intel is no longer providing this valuable archive.
If you have a project, then see if you can get the Intel linux-socfpga-xxxxx-ltsi du jur to build and run - and keep the local repo…