enabling rt preempt

enabling rt preempt

[Stephane ANCELOT]

Hi,

I have downloaded latest LTS kernel 5.4 .

For unknown reasons, I dont understand why I can't enable full rt preempt,

I enabled Embedded system to enable expert mode.

But I have not the full rt option available.

Regards

Steph

Re: enabling rt preempt

[Lukas Bulwahn]

On Wed, Dec 16, 2020 at 9:31 AM Stephane ANCELOT
<sancelot@numalliance.com> wrote:
>
> Hi,
>
> I have downloaded latest LTS kernel 5.4 .
>
> For unknown reasons, I dont understand why I can't enable full rt preempt,
>

Well, PREEMPT_RT is not available on v5.4 without the PREEMPT_RT patch set.

You can check that there is no architecture support for PREEMPT_RT on
the stable kernel. Just look at the Kconfig files defining those
config symbols.

Lukas

Re: enabling rt preempt

[Stephane ANCELOT]

Le 16/12/2020 à 09:36, Lukas Bulwahn a écrit :
> On Wed, Dec 16, 2020 at 9:31 AM Stephane ANCELOT
> <sancelot@numalliance.com> wrote:
>> Hi,
>>
>> I have downloaded latest LTS kernel 5.4 .
>>
>> For unknown reasons, I dont understand why I can't enable full rt preempt,
>>
> Well, PREEMPT_RT is not available on v5.4 without the PREEMPT_RT patch set.
Sorry, I thought it was now part of the mainstream kernel. I have not 
understand :-\
> You can check that there is no architecture support for PREEMPT_RT on
> the stable kernel. Just look at the Kconfig files defining those
> config symbols.
>
> Lukas

Re: enabling rt preempt

[Lukas Bulwahn]

On Wed, Dec 16, 2020 at 9:39 AM Stephane ANCELOT
<sancelot@numalliance.com> wrote:
>
>
> Le 16/12/2020 à 09:36, Lukas Bulwahn a écrit :
> > On Wed, Dec 16, 2020 at 9:31 AM Stephane ANCELOT
> > <sancelot@numalliance.com> wrote:
> >> Hi,
> >>
> >> I have downloaded latest LTS kernel 5.4 .
> >>
> >> For unknown reasons, I dont understand why I can't enable full rt preempt,
> >>
> > Well, PREEMPT_RT is not available on v5.4 without the PREEMPT_RT patch set.
> Sorry, I thought it was now part of the mainstream kernel. I have not
> understand :-\

PREEMPT_RT will be part of mainline on Christmas, we simply do not
know which Christmas yet... maybe on the next one?

If you rely on real-time Linux being in mainline, we can discuss
off-list which possibilities you have to ensure that that happens.

Lukas

Re: enabling rt preempt

[Luis Claudio R. Goncalves]

On Wed, Dec 16, 2020 at 09:39:31AM +0100, Stephane ANCELOT wrote:
> 
> Le 16/12/2020 à 09:36, Lukas Bulwahn a écrit :
> > On Wed, Dec 16, 2020 at 9:31 AM Stephane ANCELOT
> > <sancelot@numalliance.com> wrote:
> > > Hi,
> > > 
> > > I have downloaded latest LTS kernel 5.4 .
> > > 
> > > For unknown reasons, I dont understand why I can't enable full rt preempt,
> > > 
> > Well, PREEMPT_RT is not available on v5.4 without the PREEMPT_RT patch set.
> Sorry, I thought it was now part of the mainstream kernel. I have not
> understand :-\

The merge into upstream is an ongoing effort and is not complete yet.

Here is the announce for the latest available PREEMPT_RT patch for v5.4
(v5.4.82-rt45):

    https://www.spinics.net/lists/linux-rt-users/msg23022.html

In the message you will find instructions to get the code.

Best regards,
Luis

> > You can check that there is no architecture support for PREEMPT_RT on
> > the stable kernel. Just look at the Kconfig files defining those
> > config symbols.
> > 
> > Lukas
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