Re: [yocto] Out-of-tree Kernel Modules

[Quentin Schulz <quentin.schulz@cherry.de>]

Hi Yishai,

On 10/30/24 3:54 PM, Yishai Jaffe via Lists.Yoctoproject.Org wrote:
> You don't often get email from yishai1999=gmail.com@lists.yoctoproject.org. Learn why this is important<https://aka.ms/LearnAboutSenderIdentification>
> Thanks Quentin,
> Changing the include to uapi/linux/sched/types.h solved the issue.
> But just so I'm clear on this - Can you explain when I should use uapi headers vs when to use the regular linux/xxx headers?
> 

You should include the header where the structure is defined.

The "issue" in Yocto is that the headers aren't coming from your kernel 
sources but from a generic linux kernel header recipe, and this is made 
on purpose. The generic linux kernel header recipe is at 6.6 in 
Scarthgap. Styhead has 6.10. The structure is defined in a different 
header in 6.6 and in 6.7+ (including 6.10), so your out-of-tree module 
needs the path from 6.6 in order to compile in Scarthgap, but will need 
another path from 6.7+ in order to compile in Styhead.

You can handle that via #if in your code, if you need the exact same 
source code to build on different Yocto/kernel versions. That is the 
cross to bear when one develops out of tree kernel modules sadly.

Cheers,
Quentin