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

["Bajjuri, Praneeth" <praneeth@ti.com>]

On 12/22/2025 5:34 AM, Romain Naour wrote:
> 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.

Yes , But the fixes should be going thru the v6.12 stable tree IMO and 
v6.18 stable as well moving forward.


  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...

I hope the same as well. The other reason we are monitoring v6.18-rt is 
for arm32 platform support to mainline
Reading FWIW : 
https://e2e.ti.com/support/processors-group/processors/f/processors-forum/1578136/am4378-support-status-of-am4378-soc 


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

Agreed, We are evaluating these fixes and will bring up with real time 
linux and keep you posted here once analysis is completed.
FYI : TI is a member for RT Linux https://realtime-linux.org/membership/

>>
>> 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

Yes, We have just started LTS Migration process and will migrate all 
features/drivers from January to 
https://git.ti.com/cgit/ti-linux-kernel/ti-linux-kernel/log/?h=ti-linux-6.18.y 
(Including the remoteproc changes you mentioned)


> 
>>
>> 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)

for uboot, currently pulling the latest rc tag to 
https://git.ti.com/cgit/ti-u-boot/ti-u-boot/log/?h=ti-u-boot-2026.01 , 
But the plan is to pull till final 2026.01 tag is made and then port the 
delta patches from upstream backport and ti-u-boot-2025.01 branches.


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

Thank you that will be good. Till Wrynose is tagged, We will continue to 
use Yocto master with 6.18 and 2026.01 branches for migration effort.


> 
> 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 ''}
>