powerpc: 32BIT vs. 64BIT (PPC32 vs. PPC64)

[Mathieu Malaterre]

On Sun, Jul 8, 2018 at 1:53 PM Michael Ellerman <mpe at ellerman.id.au> wrote:
>
> Randy Dunlap <rdunlap at infradead.org> writes:
> > Hi,
> >
> > Is there a good way (or a shortcut) to do something like:
>
> The best I know of is:
>
> > $ make ARCH=powerpc O=PPC32 [other_options] allmodconfig
> >   to get a PPC32/32BIT allmodconfig
>
> $ echo CONFIG_PPC64=n > allmod.config
> $ KCONFIG_ALLCONFIG=1 make allmodconfig
> $ grep PPC32 .config
> CONFIG_PPC32=y
>
> Which is still a bit clunky.
>
>
> I looked at this a while back and the problem we have is that the 32-bit
> kernel is not a single thing. There are multiple 32-bit platforms which
> are mutually exclusive.
>
> eg, from menuconfig:
>
>  - 512x/52xx/6xx/7xx/74xx/82xx/83xx/86xx
>  - Freescale 85xx
>  - Freescale 8xx
>  - AMCC 40x
>  - AMCC 44x, 46x or 47x
>  - Freescale e200

Most Linux distro seems to have drop support for ppc32. So I'd suggest
to pick Debian powperc default config (but I agree that I am a little
biased here).

>
> So we could have a 32-bit allmodconfig, but we'd need to chose one of
> the above, and we'd still only be testing some of the code.
>
> Having said that you're the 2nd person to ask about this, so we should
> clearly do something to make a 32-bit allmodconfig easier, even if it's
> not perfect.
>
> cheers