Re: tools/testing/selftests

[Li Wang <liwang@redhat.com>]

On Mon, Mar 30, 2026 at 05:09:54PM -0700, Andrew Morton wrote:
> On Sun, 29 Mar 2026 18:04:52 +0800 Li Wang <liwang@redhat.com> wrote:
> 
> > > ts:/usr/src/25> cat Makefile
> > > # Automatically generated by /usr/src/25/Makefile: don't edit
> > > export KBUILD_OUTPUT = .
> > > export KBUILD_EXTMOD = /usr/src/25
> > > export KBUILD_EXTMOD_OUTPUT = /usr/src/25
> > > include /usr/src/25/Makefile
> > > 
> > > I've done this twice in succession now.  Any suggestions where I should
> > > look?
> > 
> > When build selftests from the top-level, sub-makes entered via `-C` may
> > still inherit the caller's PWD from the environment.
> > 
> > Some selftests use $(PWD) in recursive kbuild invocations, which can
> > then incorrectly resolve to the kernel top directory instead of the
> > current test directory.
> > 
> > Maybe try export PWD in the ../selftests/lib.mk?
> > 
> >   export PWD := $(CURDIR)
> 
> Thanks, I'll get onto this stuff soon.
 
I have created a patchset for those build tiny issues,
let me send out to you to have a early try?

> Meanwhile, shouldn't this work?
> 
> ts:/usr/src/25/tools/testing/selftests/mm> make merge.i
> make: *** No rule to make target 'merge.i'.  Stop.

That's probably because Makefile explicitly disables the implicit .c to .i rule.

In line#43 of Makefile:

    MAKEFLAGS += --no-builtin-rules

I doubt do we really need to add back the 'gcc -E' approach? 
The selftests build system intentionally kills built-in rules to prevent
half-broken implicit builds.
(the comment line# 33~42 in the Makefile explains why)

-- 
Regards,
Li Wang