[Buildroot] inquiry | configuring for a specific linux lts

[James Knight]

Trying to figure out the best way with Buildroot to target a specific
Linux LTS branch for images. At this time, using a setup that has an
external toolchain build (v6.6.x Linux headers) and inside each
project configurations a `BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE`
option is specified to a value of (for example) `6.6.32`. As Buildroot
evolves, it may update its own configuration and Linux hashes to a
more recent version (e.g. v6.6.33). In turn, when updating the
Buildroot version to use, there is a need to update all configurations
to use the most recent LTS version.

I am looking for a capability somewhat provided by the existing
`BR2_LINUX_KERNEL_LATEST_VERSION` option, but targeting a specific LTS
version. For example:

    BR2_LINUX_KERNEL_LATEST_VERSION
    BR2_LINUX_KERNEL_LATEST_LTS_0606_VERSION
    BR2_LINUX_KERNEL_LATEST_LTS_0601_VERSION
    BR2_LINUX_KERNEL_LATEST_LTS_0516_VERSION
    ...

Then these configurations can use whatever the latest LTS version of a
configured major-minor without updating.

I imagine this may not be implemented since these additional
configuration options may be a bit too much to maintain. Assuming such
an approach is not desired, I wonder if it may be possible to support
a `BR2_LINUX_KERNEL_CUSTOM_VERSION_VALUE` option where users can
define a value such as `6.6.` (or `6.6.x` or whatever) and have
Buildroot use whatever the most recent version it "supports" (e.g. has
a hash reference).

For now, it seems the tasks needed to handle an updated Buildroot
framework with a custom Linux version is to first have projects
track/patch the hash version of Linux any time a custom version is
set; and update both the version and patch-hash in a board
configuration when wanting to update.

If I am overlooking another way to approach this, please let me know.