Re: [PATCH v3 11/11] selftests: error out if kernel header files are not yet built

[Peter Zijlstra <peterz@infradead.org>]

On Fri, Nov 03, 2023 at 01:59:28PM +0100, David Hildenbrand wrote:

> Okay. the question is if your workflow can be easily adjusted, or if we can
> improve that header handling as a whole.

So on IRC the following was suggested:

  make O=defconfig-build headers ; make O=defconfig-build -C tools/testing/selftests/x86

But that makes absolutely no sense to me; because the headers and
selftests are not .config dependent. Furthermore I don't want them in a
kernel build dir.

> The problem I had with this recently: just because we did a "make headers"
> once in a git tree doesn't mean that it is still up-to-date.
> 
> So once some selftest changes showed up that require newer headers, building
> the selftests again fails without a hint that another round of "make
> headers" would be required.

Yeah, so I've been adding #ifndef guards all over the place for decades
and that just works. You need it in normal userspace too.

This super reliance on the very latestesetst headers is just a total
pain.