On Sun, Nov 30, 2025 at 11:09:25PM +0000, david laight wrote:

On Sun, 30 Nov 2025 21:44:46 +0200
Andy Shevchenko [off-list ref] wrote:

...

It is worth checking whether the files get included anyway, and whether it
really makes that much difference.

Fiddling with kernel.h and extracting small 'leaf' headers from it is also
unlikely to make a big difference.

It makes a big difference for the kernel.h and its (ab)users.
Especially when we have cyclic dependencies and "include everything"
cases due to other _headers_ including kernel.h.

Try adding a syntax error to (say) sys/ioctl.h and see where it is included
from the first time - I suspect you'll be surprised.
Working on that include list might be more fruitful (in reducing build times).

kernel.h elimination (in the form it exists right now) is very fruitful.
However, you may help with the (say) ioctl.h or whatever you consider
really fruitful, we all will thank you (no jokes).

-- 
With Best Regards,
Andy Shevchenko