Hi Jessica,

On Wed, 10 Feb 2021 09:06:48 +0100 Jessica Yu [off-list ref] wrote:

Sorry, by "feature" I meant CONFIG_TRIM_UNUSED_KSYMS. This config
option was introduced around v4.7. If simply enabling it produces
these compilation errors I was wondering if it ever built properly on
powerpc.

Ah, of course.  So for a quick fix, you could revert just the changes
to lib/Kconfig and all the defconfigs.  That way all the UNUSED_SYMBOLS
infrastructure is still removed, but TRIM_UNUSED_KSYMS remains (un)set
whenever it used to be (un)set and that could then be cleaned up in a
followup patch set per architecture when we know it works.
-- 
Cheers,
Stephen Rothwell