Re: Question about the maintenance of OOT RT patches for LTS releases (v12.x and v18.x)

On 2026-06-22 13:11:59 [-0300], Luis Claudio R. Goncalves wrote:
> Hello!
> 
> The question is simple:
> 
>    Should we have somebody maintaining the OOT RT patches for v12.x and v18.x,
>    the LTS versions that already have PREEMPT_RT in-tree?
> 
> As we still have a few OOT patches, after a while, people using PREEMPT_RT on
> those versions may encounter conflicts trying to apply the old patches. And
> as those patches are not in-tree, the fixes won't probably be routed via
> Stable.

For 6.18, we have:
- 8250 console
- i915
- arm-32
- powerpc

For 6.12, we have additionally
- ktimers thread
- the whole lazy-preempt

So for v6.12 there are bits outstanding which can impact you.
For v6.18 if you are on arm64 then the mainline version is slightly
better than on x86 because on arm64 you might be using the pl011 UART
which has nbcon support since v6.15 while on x86 you almost always have
the 8250 which is not yet with nbcon support in-tree.

These are the missing bits. None of them are essential. If you on x86
and your kernel crashes, it is more likely to see a backtrace with nbcon
driver than without it.

> Best regards,
> Luis

Sebastian