Code review comment for lp:~smoser/maas-images/trunk.v3-formatting

Hi Scott,

Approving your branch. As far as your questions:

In the past, MAAS would use "subarch" on a machine to differentiate between generic/hwe-t/hwe-x/etc kernels. Starting from MAAS 1.9, however, MAAS no longer bundles a "kernel" as part of the subarch. We have a separate attribute to define the kernel that machine will obtain. For example:

1. arch = amd64
2. subarch = generic
3. hwe_kernel = hwe-t, hwe-x, hwe-16.10-lowlatency

That said, however, the only place where "subarches" still exist in MAAS is for the import process because that's the way how the streams defined additional kernels. In other words, the streams were originally designed to provide kernel flavors as subarches.

That said, I'm fine with improving the streams to make the additional separation between what a subarch is and what a kernel flavor is (whether it is hwe-x, hwe-t or hwe-16.10-lowlatency), but I think that since this would impact the MAAS image import process, we should discuss this at the upcoming sprint, and evaluate what the impact is. For now, we will continue to assume, in the streams, that subarch provide the kernel flavors.