[yocto] How to export kernel specific headers to userspace

[Khem Raj]

On 6/18/18 10:19 PM, Ankit Rastogi wrote:
> Hi,
> 
> 
> Can someone provide any pointers on how to export kernel specific 
> headers to userspace?
> 
> I am getting below error while building our one of the component which 
> requires kernel uapi headers.
> 
> Error Received:
>   /hdmi-capture/main.c:16:10: fatal error: linux/hdmi_info.h: No such 
> file or directory
>> |  #include <linux/hdmi_info.h>
>> |           ^~~~~~~~~~~~~~~~~~~
>> | compilation terminated.
> 
> In yocto 2.5, userspace is boot strapped with linux-libc-headers package 
> which uses a set of uapi headers from Linux kernel 4.15. Can someone 
> suggest for custom kernels, how to expose uapi headers to userspace? 
> Thus create a separate linux-apl-headers package with those files.
> 

you can write your own kernel headers recipe and make that preferred 
provider.

or you can add patch to existing recipe.

I would suggest that be careful to expose the APIs here, if its already 
an UAPI in later versions of kernel and you are backporting to an older 
version it might be fine but ramdom header export would land you in 
problems later.

> Thanks,
> Ankit
> 
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