> Why is Ubuntu second guessing Intel in deciding which microcode update to apply and which to skip? How would Ubuntu know that better than the manufacturer?
The whole point of an LTS release is that they will keep a stable baseline for all the packages they're distributing and apply a certain amount of integration testing. If you believe upstream knows best (and I'm not saying you're wrong to do so) then why use LTS in the first place?
> The whole point of an LTS release is that they will keep a stable baseline
I think you're confusing an objective (LTS) with a tactic (keeping a stable baseline). Certainly the whole point of LTS is not to keep a stable baseline, but to provide long-term support. And that is clearly violated when Ubuntu chooses to not provide support when it is known to be needed (e.g., listed in an Intel Spec update) and a solution is available by a vendor (e.g., Linux-specific microcode update being made available by Intel). The whole point of LTS is to avoid the bleeding edge while fixing known bugs. Microcode updates is not bleeding edge, it's just patches for known bugs.
> the whole point of LTS is not to keep a stable baseline, but to provide long-term support.
No, you've got it backwards. If you just wanted long-term support you'd use a rolling release distribution, of which there are any number (yes some rolling release options are "bleeding edge", but there are stable options too). The whole point of LTS releases is that they are stable baselines that are supported in the long term.
If LTS' sole point were to keep a stable baseline, then that point would only be for the benefit of some short-sighted developer whose only interest were to keep his to-do list brief. Even a slightly more forward-looking developer would realize his work's point lies somewhere else, particularly when done in a corporate environment such as Canonical's and not as a hobby (but even when done as a hobby for a community project such as Debian). His work should be oriented towards goals somehow related to the costumer priorities, without whom it ceases to matter. Keeping a stable baseline is unrelated to any costumer or user interest.
The costumer or user of LTS wants, well, Support (fixes) for some extended time (Long Term) and avoiding problems (less bugs), perhaps at the cost of getting less new features. The whole point of LTS is self-explanatory.
Keeping a stable baseline is a tactic used to try to provide long-term support by reducing the amount of new bugs at the cost of less new features. But keeping a stable baseline does not attain the key word, the substantive in LTS: Support. Support is provided only by introducing fixes, and that is exactly what has been omitted in the case of the Intel microcode bugs.
The whole point of an LTS release is that they will keep a stable baseline for all the packages they're distributing and apply a certain amount of integration testing. If you believe upstream knows best (and I'm not saying you're wrong to do so) then why use LTS in the first place?