Linux stable: 4.19 vs 4.14

[Avinash Patil]

Thanks for the response, Valdis.

Thanks,
Avinash

On Sat, Nov 2, 2019 at 10:54 AM Valdis Klētnieks
<valdis.kletnieks at vt.edu> wrote:
>
> On Fri, 01 Nov 2019 14:24:26 -0700, Avinash Patil said:
> > Hi Greg,
>
> I'm not Greg, but... :)
>
> > I am curious as to why Linux4.19 which was released later has earlier
> > EOL than 4.14?
>
> Not all stable releases are kept going for the same amount of time.  Most go
> EOL as soon as a few newer releases have come out, while every 5th one or so is
> kept going for longer.
>
> > If we have to choose one version over another for BSP, which one is preferred?
>
> If you're planning to dump unsupported crap on customers, it doesn't matter.
> Let's face it - if you're not going to provide updates, when a stable stream
> EOLs doesn't matter if you ship 4.19.81 or 4.14.151, because your customers
> aren't ever going to get 4.19.104 or 4.14.183.
>
> But you probably want to base the BSP on 4.19 so that your customers get the benefit
> of all the stuff that got fixed between 4.14 and 4.19.  Remember that only a *very* small
> fraction of fixes - those that qualify under Documentation/process/stable-kernel-rules.rst
> get included in the stable tree.
>
> And of course, unless you have no intention of building similar boards in the future,
> it's a good idea to upstream any custom drivers.  That way, when your follow-on
> BSP gets based to the 5.11 kernel, your drivers are already in-tree, and even more
> importantly, already updated to any 5.11 kernel API changes, because anybody who
> changed a kernel API was required to update your driver for you.
>
> (And no, "We only plan to sell 50,000 so it's not worth it" is not a valid excuse.  There's
> plenty of stuff that's in-tree that's very niche with only a few users.  Heck, we kept
> an entire architecture (the i386 Voyager) around for 2 machines.  Not two models,
> two physical machines.  We finally dropped it when James Bottomley was unable to
> mix-and-match parts from the two machines to get either one to boot....)
>