How to set real time patch correctly? #honister

How to set real time patch correctly? #honister

[Haimbach]

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Hello,

I'm wondering what is the *best way to* patch properly kernel with RT-PATCH in distribution?(specific in HONISTER)

For an example I checkout HONISTER commit with has the kernel 5.15.36 which is LTS and now I want to patch with correct RT-patch to this version.
which I can be found here: https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.15/older/patch-5.15.36-rt41.patch.gz

Regards,
Haim

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Re: [yocto] How to set real time patch correctly? #honister

[Gyorgy Sarvari]

One painless way would be to set
PREFERRED_PROVIDER_virtual/kernel = "linux-yocto-rt"
somewhere (e.g. distro.conf, machine.conf, local.conf... whatever fits 
best your case).

Setting this will fetch the kernel source from a branch that has the 
patch applied already.

Re: [yocto] How to set real time patch correctly? #honister

[חיים בכר]

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Hi and what if the recipe is linux-xlnx then set
PREFFERED_PROVIDER_virtual/kernel = “linux-xlnx-rt”?

By the way what the different between linux-yocto and linux-xlnx?


בתאריך שבת, 26 באוק׳ 2024 ב-16:55 מאת Gyorgy Sarvari <skandigraun@gmail.com
>:

> One painless way would be to set
> PREFERRED_PROVIDER_virtual/kernel = "linux-yocto-rt"
> somewhere (e.g. distro.conf, machine.conf, local.conf... whatever fits
> best your case).
>
> Setting this will fetch the kernel source from a branch that has the
> patch applied already.
>

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Re: [yocto] How to set real time patch correctly? #honister

[Gyorgy Sarvari]

On 10/26/24 15:59, חיים בכר wrote:
> Hi and what if the recipe is linux-xlnx then set 
> PREFFERED_PROVIDER_virtual/kernel = “linux-xlnx-rt”?
> 
> By the way what the different between linux-yocto and linux-xlnx?
> 

linux-yocto (and its -rt variant) is the default kernel coming with 
Yocto. linux-xlnx comes from Xilinx, with their own modifications, and 
looking at meta-xilinx layer, there doesn't seem to be a recipe with the 
RT patch available.

If you are not using the default kernel, then possibly the simplest 
would be to create a bbappend for your kernel recipe, where you add the 
patch's uri to SRC_URI (assuming it applies cleanly on the vendor's 
kernel still), e.g:

SRC_URILappend = " 
https://cdn.kernel.org/pub/linux/kernel/projects/rt/5.15/older/patch-5.15.36-rt41.patch.gz"

After fetching the source bitbake will extract the patch and apply it 
automatically before compiling.

(If the patch doesn't apply on the xlnx kernel, then maybe Xilinx 
support has some extra info on this? Adapting that patch could be a 
non-trivial task)

Re: [yocto] How to set real time patch correctly? #honister

[Haimbach]

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Do you know if there any example of setting the rt patch with Xilinx kernel?
the default procedure not working as you say it’s for the vanilla kernel.

Regards,
Haim

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Re: [yocto] How to set real time patch correctly? #honister

[Gyorgy Sarvari]

Based on some random googling[0], the RT patch is not supported 
officially by the Xilinx kernel - and there is a not too nice unofficial 
way, which doesn't look something that can be done nicely without hacks 
using Yocto at the first sight.

Personally I would just prepare the source manually along some update 
script, and host it on my local server to fetch it from... but possibly 
the folks at meta-xilinx mailing list[1] could be a better help? It's 
their kernel, most likely they have more hands-on experience.

[0]: 
https://xilinx-wiki.atlassian.net/wiki/spaces/A/pages/18842435/Real-Time+Linux
[1]: https://lists.yoctoproject.org/g/meta-xilinx

Re: [yocto] How to set real time patch correctly? #honister

[codusnocturnus]

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It’s tough with the llinux-xlnx kernels, because they include some stuff from the RT patches, and you have to modify the patch files to get them to apply. Then there are things that patch okay, but break the build, and you have to chase that down.

Updating the patches can definitely be tedious, but I keep the result (as a full patch set) along with a bbappend in my local layer.

I’ve been able to get a working PREEMPT-RT kernel into my images, followed by lots of testing (currently on 2023.2/Langdale).

Really can’t wait for kernel 6.12 to make it into a yocto release and then into linux-xlnx.

Sent from [Proton Mail](https://proton.me/mail/home) for iOS

On Sun, Oct 27, 2024 at 13:01, Gyorgy Sarvari <[skandigraun@gmail.com](mailto:On Sun, Oct 27, 2024 at 13:01, Gyorgy Sarvari <<a href=)> wrote:

> Based on some random googling[0], the RT patch is not supported
> officially by the Xilinx kernel - and there is a not too nice unofficial
> way, which doesn't look something that can be done nicely without hacks
> using Yocto at the first sight.
>
> Personally I would just prepare the source manually along some update
> script, and host it on my local server to fetch it from... but possibly
> the folks at meta-xilinx mailing list[1] could be a better help? It's
> their kernel, most likely they have more hands-on experience.
>
> [0]:
> https://xilinx-wiki.atlassian.net/wiki/spaces/A/pages/18842435/Real-Time+Linux
> [1]: https://lists.yoctoproject.org/g/meta-xilinx
>
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Re: [yocto] How to set real time patch correctly? #honister

[Haimbach]

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Thanks for the answer,

Ill read those wiki and mailing list

Regards,
Haim

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Re: [yocto] How to set real time patch correctly? #honister

[Bruce Ashfield]

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Alternatively:

https://git.yoctoproject.org/linux-yocto/log/?h=v6.6/standard/preempt-rt/sdkv6.6/xlnx-soc

Also, please anyone reading this. Do not expect any magic from 6.12 to make
all your -rt dreams come true. Outside of patching the kernel, all of the
challenges with supporting -rt in embedded SDKs and devices will be exactly
the same. Dust off our tracing and latency spike debugging skills, because
you are going to need them.

Cheers,

Bruce

On Sat, Oct 26, 2024 at 1:10 PM Haimbach via lists.yoctoproject.org
<haimbachar2008=gmail.com@lists.yoctoproject.org> wrote:

> Do you know if there any example of setting the rt patch with Xilinx
> kernel?
> the default procedure not working as you say it’s for the vanilla kernel.
>
> Regards,
> Haim
>
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> bruce.ashfield@gmail.com]
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>

-- 
- Thou shalt not follow the NULL pointer, for chaos and madness await thee
at its end
- "Use the force Harry" - Gandalf, Star Trek II

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Re: [yocto] How to set real time patch correctly? #honister

[codusnocturnus]

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No magic expected. It will just be nice to not have to essentially merge 3 kernel flavors together to get full RT going.

I hadn’t seen (or looked for) the Xilinx tags in linux-yocto before. I’ve always been leery about using anything other than linux-xlnx. There are usually enough things to do when moving between Xilinx yocto releases that I haven’t wanted to add more things to remember, but I will definitely take a look.

Thanks,

Sent from [Proton Mail](https://proton.me/mail/home) for iOS

On Sun, Oct 27, 2024 at 15:20, Bruce Ashfield <[bruce.ashfield@gmail.com](mailto:On Sun, Oct 27, 2024 at 15:20, Bruce Ashfield <<a href=)> wrote:

> Alternatively:
>
> https://git.yoctoproject.org/linux-yocto/log/?h=v6.6/standard/preempt-rt/sdkv6.6/xlnx-soc
>
> Also, please anyone reading this. Do not expect any magic from 6.12 to make all your -rt dreams come true. Outside of patching the kernel, all of the challenges with supporting -rt in embedded SDKs and devices will be exactly the same. Dust off our tracing and latency spike debugging skills, because you are going to need them.
>
> Cheers,
>
> Bruce
>
> On Sat, Oct 26, 2024 at 1:10 PM Haimbach via lists.yoctoproject.org <haimbachar2008= gmail.com@lists.yoctoproject.org> wrote:
>
>> Do you know if there any example of setting the rt patch with Xilinx kernel?
>> the default procedure not working as you say it’s for the vanilla kernel.
>>
>> Regards,
>> Haim
>
> --
>
> - Thou shalt not follow the NULL pointer, for chaos and madness await thee at its end
> - "Use the force Harry" - Gandalf, Star Trek II

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Re: [yocto] How to set real time patch correctly? #honister

[Bruce Ashfield]

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On Sun, Oct 27, 2024 at 6:49 PM codusnocturnus via lists.yoctoproject.org
<codusnocturnus=protonmail.com@lists.yoctoproject.org> wrote:

> No magic expected. It will just be nice to not have to essentially merge 3
> kernel flavors together to get full RT going.
>

I'm not exactly sure what that means in your context, but that isn't
important since I don't need to :)

I just wanted my statement to be on the record, since the amount of people
who think that something fundamental has changed is quite surprising. But
clearly, that isn't the case here, and you are going into things eyes wide
open!



>
> I hadn’t seen (or looked for) the Xilinx tags in linux-yocto before. I’ve
> always been leery about using anything other than linux-xlnx. There are
> usually enough things to do when moving between Xilinx yocto releases that
> I haven’t wanted to add more things to remember, but I will definitely take
> a look.
>
>
Full disclosure. I work for AMD/Xilinx (but you may have known that), so
there's some assurance that what makes it into linux-yocto is aligned with
other sources. Wind River contributes the SDK ports, so they are tested and
supported from that level as well.

Bruce



> Thanks,
>
>
>
> Sent from Proton Mail <https://proton.me/mail/home> for iOS
>
>
> On Sun, Oct 27, 2024 at 15:20, Bruce Ashfield <bruce.ashfield@gmail.com
> <On+Sun,+Oct+27,+2024+at+15:20,+Bruce+Ashfield+%3C%3Ca+href=>> wrote:
>
> Alternatively:
>
>
> https://git.yoctoproject.org/linux-yocto/log/?h=v6.6/standard/preempt-rt/sdkv6.6/xlnx-soc
>
> Also, please anyone reading this. Do not expect any magic from 6.12 to
> make all your -rt dreams come true. Outside of patching the kernel, all of
> the challenges with supporting -rt in embedded SDKs and devices will be
> exactly the same. Dust off our tracing and latency spike debugging skills,
> because you are going to need them.
>
> Cheers,
>
> Bruce
>
> On Sat, Oct 26, 2024 at 1:10 PM Haimbach via lists.yoctoproject.org
> <haimbachar2008= gmail.com@lists.yoctoproject.org> wrote:
>
>> Do you know if there any example of setting the rt patch with Xilinx
>> kernel?
>> the default procedure not working as you say it’s for the vanilla kernel.
>>
>> Regards,
>> Haim
>>
>>
>>
>>
>
> --
> - Thou shalt not follow the NULL pointer, for chaos and madness await thee
> at its end
> - "Use the force Harry" - Gandalf, Star Trek II
>
>
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> bruce.ashfield@gmail.com]
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>

-- 
- Thou shalt not follow the NULL pointer, for chaos and madness await thee
at its end
- "Use the force Harry" - Gandalf, Star Trek II

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