Re: [meta-ti][master/scarthgap][PATCH 1/4] linux-ti-staging: Add v6.12 recipe

[Romain Naour <romain.naour@smile.fr>]

Hello Bajjuri,

Le 19/12/2025 à 21:58, Bajjuri, Praneeth a écrit :
> Hi Romain,
> 
> On 12/19/2025 11:31 AM, Romain Naour wrote:
>> Hello,
>>
>> Le 04/10/2024 à 17:18, Ryan Eatmon via lists.yoctoproject.org a écrit :
>>> Adding needed recipes for initial testing and development of the 6.12
>>> kernel for the next LTS.
>>>
>>> Signed-off-by: Ryan Eatmon <reatmon@ti.com>
>>> ---
>> ...
>>>   .../linux/linux-ti-staging-rt_6.12.bb         |  9 +++++
>>>   create mode 100644 meta-ti-bsp/recipes-kernel/linux/linux-ti-staging-
>>> rt_6.12.bb
>> ...
>>> diff --git a/meta-ti-bsp/recipes-kernel/linux/linux-ti-staging-rt_6.12.bb b/
>>> meta-ti-bsp/recipes-kernel/linux/linux-ti-staging-rt_6.12.bb
>>> new file mode 100644
>>> index 00000000..9e5c4ee4
>>> --- /dev/null
>>> +++ b/meta-ti-bsp/recipes-kernel/linux/linux-ti-staging-rt_6.12.bb
>>> @@ -0,0 +1,9 @@
>>> +require linux-ti-staging_6.12.bb
>>> +
>>> +KERNEL_LOCALVERSION:append = "-rt"
>>> +
>>> +# Look in the generic major.minor directory for files
>>> +# This will have priority over generic non-rt path
>>> +FILESEXTRAPATHS:prepend := "${THISDIR}/${PN}-6.12:"
>>
>> Previous linux-ti-staging-rt recipes [1] used a specific branch
>> "ti-rt-linux-6.1.y" obtained by merging the TI vendor "ti-linux-6.1.y" branch
>> and the preempt-rt v6.1-rt branch [2].
>>
>>    BRANCH = "ti-rt-linux-6.1.y"
>>
>> Since preempt-rt is now merged in the kernel 6.12, indeed we can use the same
>> kernel sources with a specific configuration fragment (hence there is no
>> ti-rt-linux-6.12.y [3]).
>>
>> But the preempt-rt project still maintain a v6.12-rt branch with all remaining
>> patches [4]. Actually the project still recommend to apply the latest PREEMPT_RT
>> patches [5].
>>
>> Should the linux-ti-staging-rt recipe follow the preempt-rt stable branch as
>> before?
>>
>> Porting existing project (kirkstone 6.1 -> scarthgap 6.12) using
>> linux-ti-staging-rt recipe, users may expect that this recipe still use the
>> preempt-rt stable branch.
>>
>> Thoughts?
> 
> Indeed when we started 6.12 LTS baseline migration, Since PREEMPT_RT is part of
> mainline we have started using a unified kernel branch ( With config fragment
> switch) to build RT and non RT baselines.
> 
> The preempt-rt project didnt have a 6.12 branch till august in the year at
> https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-stable-rt.git/
> 
> The development and hosting of v6.12-rt including additional on the fly features
> is something new and i hope it continue with next LTS (6.18 as well)

Preempt-rt issues are fixed over the time, especially for the 6.12 kernel since
it's the first release with preempt-rt included. But Preempt-rt specific changes
might be too risky to backport to linux-stable branches. We can hope that
v6.18-rt will never exist but who knows...

In other hand, it's only a few dozen of commits (as of today), some of them not
related to TI SoCs.

> 
> As you can see with https://patchwork.yoctoproject.org/project/ti/list/?
> series=41242 , we are in process of switching development with master and next
> LTS yocto to 6.18 baseline and we are assessing how and if RT need to be
> maintained as linux-ti-staging-rt-6.18 recipe based on the feature differences
> in v6.18-rt vs mainline kernel.

The linux-ti-staging-6.18 is too recent, some TI specific changes (like the
DMA-BUF support in remoteproc) is not yet rebased:

https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/commit/drivers/remoteproc/remoteproc_cdev.c?h=ti-linux-6.12.y&id=3119d723957038270225867130678d76081dee0c

> 
> 6.12 combination with scarthgap is in maintenance mode at this moment.

Ok.

> The evaluation of linux-ti-staging-rt moving forward will be for master and
> wrynose in 2026.

kernel 6.18 was released only few weeks ago (uboot 2026.01 is not released yet)

We will consider switching to Wrynose as soons as the TI-SDK will be released.

Best regards,
Romain

> 
> 
>>
>> [1]
>> https://git.yoctoproject.org/meta-ti/tree/meta-ti-bsp/recipes-kernel/linux/
>> linux-ti-staging-rt_6.1.bb?h=kirkstone#n9
>> [2]
>> https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-stable-rt.git/log/?
>> h=v6.1-rt
>> [3] https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel
>> [4]
>> https://git.kernel.org/pub/scm/linux/kernel/git/rt/linux-stable-rt.git/log/?
>> h=v6.12-rt
>> [5] https://realtime-linux.org/getting-started-with-preempt_rt-guide/
>>
>> Best regards,
>> Romain
>>
>>
>>> +
>>> +include ${@ 'recipes-kernel/linux/ti-extras-rt.inc' if d.getVar('TI_EXTRAS')
>>> else ''}