How to enable Preempt-RT function in Kernel 6.1.1 SDK

[t2865k5]

Dear NXP ,

HW: imx8mplus

SW : kernel 6.1.1

repo init -u https://github.com/nxp-imx/imx-manifest -b imx-linux-langdale -m imx-6.1.1-1.0.1.xml

I want to enable Preempt-RT function  on imx8mplus platform. I check kernel config as follows:

CONFIG_PREEMPT_BUILD=y
CONFIG_PREEMPT=y
CONFIG_PREEMPT_COUNT=y
CONFIG_PREEMPTION=y

I can't find this CONFIG_PREEMPT_RT  in kernel 6.1.1 SDK. 

 Do I need to add some patchs to the current SDK? (kernel 6.1.1)

Please tell me how to enable Preempt-RT function .

[t2865k5]

Dear Zhiming ,

Could you answer the following questions?

In kernel 6.1.1 deconfig :CONFIG_PREEMPT=y

(1) Does it enable Preempt-RT function?
(2) If the Preempt-RT function is not enabled, please provide related patches to me .

[Zhiming_Liu]

We recommand you use real-time-edge-software which has enabled Preempt-RT feature.

https://www.nxp.com/design/software/development-software/real-time-edge-software:REALTIME-EDGE-SOFTW...

[t2865k5]

Dear Zhiming ,

I can't use the real-time-edge 2.6 SDK because there is a big difference between the real-time-edge 2.6 and kernel 6.1.1 (deconfig).

In kernel 6.1.1 deconfig :CONFIG_PREEMPT=y

Does it enable Preempt-RT function?
If the Preempt-RT function is not enabled, please provide related patches to me .

[Zhiming_Liu]

Hi @t2865k5 

1.linux-imx can't support  Preempt-RT function

2. If you need patches about  Preempt-RT function, you can export them from RT kernel :

https://github.com/nxp-real-time-edge-sw/real-time-edge-linux

Best Regards

Zhiming

[t2865k5]

Dear Zhiming ,

I have some questions as follows :

(1) For real-time-edge-linux image , I can modify as follows:

CONFIG_PREEMPT_RT=y
CONFIG_PREEMPT_COUNT=y
CONFIG_PREEMPTION=y

Does it enable Preempt-RT function ?

(2) For kernel 6.1.1 image, 

CONFIG_PREEMPT=y

 what function does it have ? 

[Zhiming_Liu]

The CONFIG_PREEMPT function is missing in kernel 6.1.x

You should use Preempt-RT patches from Linux Fundation for kernel 6.1.x

https://wiki.linuxfoundation.org/realtime/preempt_rt_versions

[t2865k5]

Dear Zhiming ,

Could you answer my first question?

(1) For real-time-edge-linux image , I can modify as follows:

CONFIG_PREEMPT_RT=y
CONFIG_PREEMPT_COUNT=y
CONFIG_PREEMPTION=y

Does it enable Preempt-RT function ?

[Zhiming_Liu]

Hi @t2865k5 

Yes, but for usage of these confg, please refer comments in Kconfig.preempt

https://github.com/nxp-real-time-edge-sw/real-time-edge-linux/blob/linux_5.10.y/kernel/Kconfig.preem...

Best Regards

Zhiming