Randy Dunlap [off-list ref] writes:

On 07/09/2018 07:24 AM, Michael Ellerman wrote:

quoted

Because the allmodconfig logic just sets every symbol to M or Y, it
has the effect of always generating a 64-bit config, because
CONFIG_PPC64 becomes Y.

So to make it easier for folks to test 32-bit code, provide a phony
defconfig target that generates a 32-bit allmodconfig.

The 32-bit port has several mutually exclusive CPU types, we choose
the Book3S variants as that's what the help text in Kconfig says is
most common.

Signed-off-by: Michael Ellerman <mpe@ellerman.id.au>

Hi Michael,

ppc32_allmodconfig sets CONFIG_ISA=y (and other related symbols) and
CONFIG_PPC_CHRP=y.  But my builds are failing because they are missing
the functions isa_bus_to_virt() and isa_virt_to_bus().

Any ideas?

It's old legacy cruft that we've never implemented :)

I don't know if it's possible to implement it for CHRP, Ben implied it
might be, back in 2009:

  https://lists.ozlabs.org/pipermail/linuxppc-dev/2009-June/073232.html

But of course nothing came of it.


It looks like there's only a handful of drivers left using them, we
should probably just mark them as not buildable on PPC.

Arnd did something similar for ARM in:
  e9b106b8fbdb ("net: lance,ni64: don't build for ARM")


cheers