Re: [PATCH] xarray: port tests to kunit

[Geert Uytterhoeven <geert@linux-m68k.org>]

Hi Liam,

On Thu, 30 Jan 2025 at 16:17, Liam R. Howlett <Liam.Howlett@oracle.com> wrote:
> * Geert Uytterhoeven <geert@linux-m68k.org> [250130 09:25]:
> > On Thu, 30 Jan 2025 at 15:06, Liam R. Howlett <Liam.Howlett@oracle.com> wrote:
> > > > > it is to get m68k to build, you should probably know how to read a
> > > > > makefile.
> > > >
> > > > Like all other kernel cross-compilation? Usually you don't even have
> > > > to know where your cross-compiler is living:
> > > >
> > > >     make ARCH=m68k
> > >
> > > Ignoring that I had to make a config - which asked challenging
> > > questions...
> >
> > make ARCH=m68k defconfig
>
> That also prompts, defoldconfig did not.

Hmm, using a defconfig should never ask for questions.
Perhaps this might happen if it has an option enabled that depends on
specific compiler support?

> > > And ignoring the steps to get m68k compiler...
> >
> > apt install gcc-m68k-linux-gnu?
>
> There are a few compilers, multilib or such?  I've had issues with
> getting all the archs working for cross compile on the same machine
> (arm, arm64, riscv, m68k, ppc, ppc64, parisc).

I have installed all of the above (and more) from Ubuntu
(except for parisc, as Ubuntu does not have it), and more
from https://www.kernel.org/pub/tools/crosstool/.
All of them should work fine (for building kernels).

> > > > > > When trying the above, and ignoring failures due to missing packages
> > > > > > on my host:
> > > > > >   - there are several weird build errors,
> > > > > >   - this doesn't play well with O=,
> > > > > >   - lots of scary warnings when building for 32-bit,
> > > > > >   - ...
> > > > > >
> > >
> > > In file included from ./include/linux/sched.h:12,
> > >                  from arch/m68k/kernel/asm-offsets.c:15:
> > > ./arch/m68k/include/asm/current.h:7:30: error: invalid register name for ‘current’
> > >     7 | register struct task_struct *current __asm__("%a2");
> >
> > Which compiler are you using?
>
> I've had a hard time getting m68k to boot in qemu because of the lack of
> userspace.  I use m68k for nommu testing, but have a hard time getting
> the buildroot to work correctly to build what I need.

I only do m68k with MMU, and use Debian (ports) userland.
Perhaps https://landley.net/toybox/ might give you a nommu userland.

> More importantly, I think I get your point, you think that the testing
> should be integrated and complain if it's broken - at least by bots.  I
> don't think this is practical in all cases, unfortunately.

Exactly:
  - (cross)building kernel module tests is easy, and included in a
     kernel build, so build failures are detected early.
  - (cross)building the userland testing tools is cumbersome.
So there's an opportunity for improvement...

Thanks!

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@linux-m68k.org

In personal conversations with technical people, I call myself a hacker. But
when I'm talking to journalists I just say "programmer" or something like that.
                                -- Linus Torvalds