LTS, Stable, and Mainline are Three Categories of the Kernel and Images?

General Discussion
,
1

Linux kernel releases are categorized into Mainline, Stable, and Long-Term Support (LTS) to balance innovation with reliability.

Mainline is the newest, bleeding-edge development tree.

Stable consists of vetted mainline releases receiving bug fixes.

LTS offers, as commonly understood, long-term maintenance (2+ years) for critical infrastructure.

Mainline Definition: The main kernel tree where Linus Torvalds oversees development. It is the source for all new features, drivers, and improvements.

Release Schedule: New versions are released every 2-3 months.

Best for: Developers, testers, and users who need support for the newest hardware.

Stable Definition: A release derived from the mainline tree. Once a mainline kernel is out, it is considered “stable.”

Maintenance: Receives backported bug fixes from the mainline tree (usually weekly) until the next mainline release.

Best for: General users wanting a good balance of new features and stability.

LTS (Long Term Support) Definition:

Specific kernel versions chosen to be maintained for an extended period, often 2 to 6+ years.

Purpose: To provide a stable foundation for operating systems and servers, where changes in API/ABI (Application Binary/Interface) are undesirable.

Maintenance: Focuses solely on security updates and critical bug fixes.

Best for: Production servers, embedded devices, and enterprise environments requiring reliability over new features.

@jtbrooks , I think in another post you were inquiring about Linux kernel porting to boards and how people view this so-said port to a board in a manner that had me guessing too. I went and researched some. AI or research came up with these ideas, i.e. all of which I have read numerous times on various occasions.

It may help you understand a bit more if anything.

1 Like
2 
LTS (Long Term Support) Definition:

Specific kernel versions chosen to be 
maintained for an extended period, often 2 to 6+ years.

I think two to six years is a bit of a misnomer. It can definitely be of a longer period outside of a six year span.

I say that because I have witnessed some vendors handle their kernels well into eight years.

Eight years of no change… Yikes. People get bored or lose their lackluster ways with building and porting specifics to boards.

I mean…get this:

I even got good at building around specifics with files. I was never good at keeping notes, including files upon files to come to a summary, and I always get upset at myself when things change and I am not on the up and up.

Anyway, speaking about what I have learned here. Beagleboard.org seems to keep their process running smoothly for an elongated period of time. I remember in the 4.14.x and 4.19.x kernels, I thought I was severely tackling genius status. Nope... I got caught up in reiterations and fooled myself.

Anyway, you will see me on these forums fooling myself constantly into thinking I understand people and their wants/needs. I really may never understand what exactly it is now, during the time, that people wish or want. But! I can try!