Re: [PATCH] m68k: Define NR_CPUS to 1

[Geert Uytterhoeven]

On Mon, 3 Aug 2026 at 10:56, Uwe Kleine-König <ukleinek@xxxxxxxxxx> wrote:
> On Mon, Aug 03, 2026 at 09:58:14AM +0200, Geert Uytterhoeven wrote:
> > On Fri, 31 Jul 2026 at 11:50, Uwe Kleine-König <ukleinek@xxxxxxxxxx> wrote:
> > > This fixes a Kconfig warning
> > >
> > >         fs/erofs/Kconfig:137:warning: range is invalid
> > >
> > > which originates from EROFS_FS_ZIP_LZMA_DEFAULT_MAX_STREAMS using
> > > NR_CPUS which up to now didn't exist for ARCH=m68k. All other
> > > architectures define this symbol, so fix the outlier.
> >
> > Apart from the Kconfig warning, this also
> >   1. Breaks pressing "ENTER" in "make oldconfig" to apply a sensible
> >      default value, just repeating the question ad infinitum instead
> >      (the default is 16),
> >   2. "make olddefconfig" sets it to literal NR_CPUS, which is invalid, too.
> >
> > > Fixes: c9b47e6b2311 ("erofs: cap LZMA stream pool size")
> > > Signed-off-by: Uwe Kleine-König <ukleinek@xxxxxxxxxx>
> >
> > > --- a/arch/m68k/Kconfig.cpu
> > > +++ b/arch/m68k/Kconfig.cpu
> > > @@ -549,6 +549,10 @@ config CACHE_COPYBACK
> > >  endchoice
> > >  endif # HAVE_CACHE_CB
> > >
> > > +config NR_CPUS
> > > +       int
> > > +       default "1"
> >
> > While this does fix the issues on m68k, I don't think this is the
> > right fix:
> >   - NR_CPUS depends on SMP on most architectures, so you do not get
> >      the "range is invalid" warning on non-SMP, but NR_CPUS is zero.
> >     Hence I managed to reproduce the two issues above (albeit 2 with
> >     CONFIG_EROFS_FS_ZIP_LZMA_DEFAULT_MAX_STREAMS=0) with a non-SMP
> >     ARM config.
> >   - Kconfig logic using NR_CPUS typically includes a check for SMP, too.
> >
> > So I think EROFS_FS_ZIP_LZMA_DEFAULT_MAX_STREAMS should be fixed
> > instead.
>
> Agreed, probably it should depend on SMP, too.

Since the underlying issue can be fixed by depending on SMP, but the
warning would still be there[1], I decided to bite the bullet and take
your patch as a fix for v7.2.

Reviewed-by: Geert Uytterhoeven <geert@xxxxxxxxxxxxxx>
i.e. will queue in the m68k tree for v7.2.

[1] https://lore.kernel.org/CAMuHMdWQLwgShMK7G-6soiZxtRPYWLizBLRdouwxFUcFXUJM-Q@xxxxxxxxxxxxxx

Gr{oetje,eeting}s,

                        Geert

-- 
Geert Uytterhoeven -- There's lots of Linux beyond ia32 -- geert@xxxxxxxxxxxxxx

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