Re: [PATCH 0/4] Fix kselftest build with sub-directory

[Shuah Khan]

On 7/11/22 6:13 AM, Anders Roxell wrote:
> On Fri, 8 Jul 2022 at 19:14, Shuah Khan <skhan@xxxxxxxxxxxxxxxxxxx> wrote:
> > On 7/8/22 10:23 AM, Guillaume Tucker wrote:
> > > Earlier attempts to get "make O=build kselftest-all" to work were
> > > not successful as they made undesirable changes to some functions
> > > in the top-level Makefile.  This series takes a different
> > > approach by removing the root cause of the problem within
> > > kselftest, which is when the sub-Makefile tries to install kernel
> > > headers "backwards" by calling make with the top-level Makefile.
> > > The actual issue comes from the fact that $(srctree) is ".." when
> > > building in a sub-directory with "O=build" which then obviously
> > > makes "-C $(top_srcdir)" point outside of the real source tree.
> > >
> > > With this series, the generic kselftest targets work as expected
> > > from the top level with or without a build directory e.g.:
> > >
> > >     $ make kselftest-all
> > >
> > >     $ make O=build kselftest-all
> > >
> > > Then in order to build using the sub-Makefile explicitly, the
> > > headers have to be installed first.  This is arguably a valid
> > > requirement to have when building a tool from a sub-Makefile.
> > > For example, "make -C tools/testing/nvdimm/" fails in a similar
> > > way until <asm/rwonce.h> has been generated by a kernel build.
> > >
> > > Guillaume Tucker (4):
> > >     selftests: drop khdr make target
> > >     selftests: stop using KSFT_KHDR_INSTALL
> > >     selftests: drop KSFT_KHDR_INSTALL make target
> > >     Makefile: add headers_install to kselftest targets
> >
> > This takes us to back to the state before b2d35fa5fc80 added
> > khdr support. I reluctantly agreed to the change and it has
> > proven to be a problematic change. I would rather have had the
> > dependency stated that headers should be installed prior to
> > building tests - test build depends on kernel build anyway and
> > having dependency on headers having build isn't a huge deal.
>
> I agree that it's not a huge deal.
>
> > So I am in favor of getting rid of khdr support. However, this
> > khdr support was a change originated from Linaro test ring. Undoing
> > this might have implication on their workflow.
>
> It shouldn't be a problem.
> I've been running these patches through a smoke test and it looks
> good.
>
> Tested-by: Anders Roxell <anders.roxell@xxxxxxxxxx>

Thank you Anders for confirming this isn't a problem for Linaro workflow
and testing.

Than you Guillaume for fixing the problem. I will apply these for 5.20-rc1.

thanks,
-- Shuah