* Michael Ellerman [off-list ref] [2020-09-17 21:28:46]:

On Tue, 8 Sep 2020 22:58:50 +1000, Michael Ellerman wrote:

quoted

When we added the VDSO32 kconfig symbol, which controls building of
the 32-bit VDSO, we made it depend on CPU_BIG_ENDIAN (for 64-bit).

That was because back then COMPAT was always enabled for 64-bit, so
depending on it would have left the 32-bit VDSO always enabled, which
we didn't want.

[...]

Applied to powerpc/next.

[1/1] powerpc/64: Make VDSO32 track COMPAT on 64-bit
      https://git.kernel.org/powerpc/c/231b232df8f67e7d37af01259c21f2a131c3911e

cheers

With this commit which is part of powerpc/next and with
/opt/at12.0/bin/gcc --version
gcc (GCC) 8.4.1 20191125 (Advance-Toolchain 12.0-3) [e25f27eea473]
throws up a compile error on a witherspoon/PowerNV with CONFIG_COMPAT.
CONFIG_COMPAT got carried from the distro config. (And looks like most
distros seem to be having this config)

cc1: error: _-m32_ not supported in this configuration
make[4]: *** [arch/powerpc/kernel/vdso32/sigtramp.o] Error 1
make[4]: *** Waiting for unfinished jobs....
cc1: error: _-m32_ not supported in this configuration
make[4]: *** [arch/powerpc/kernel/vdso32/gettimeofday.o] Error 1
make[3]: *** [arch/powerpc/kernel/vdso32] Error 2
make[3]: *** Waiting for unfinished jobs....
make[2]: *** [arch/powerpc/kernel] Error 2
make[2]: *** Waiting for unfinished jobs....
make[1]: *** [arch/powerpc] Error 2
make[1]: *** Waiting for unfinished jobs....
make: *** [__sub-make] Error 2

I don't seem to be facing with other compilers like "gcc (Ubuntu
7.4.0-1ubuntu1~18.04.1) 7.4.0" and I was able to disable CONFIG_COMPAT and
proceed with the build.

-- 
Thanks and Regards
Srikar Dronamraju