Re: objtool warnings for kernel/trace/trace_selftest_dynamic.o

From: Andi Kleen
Date: Mon Dec 17 2018 - 23:22:10 EST

> The plugin is only used for older versions of GCC. Newer versions have
> the same functionality builtin with -fsanitize-coverage=trace-pc.

Ok and the frame pointer issue is with the older version only?

> So the problem is GCC. We're using a function attribute which at least
> oneGCC developer doesn't recommend. If you want to keep the LTO support
> then '__used' seems like a much better choice.

I guess __used will work for now.

Still would be better to root cause it properly, but I guess that's
ok for now. The lack of understanding may eventually come back
to bite you later.

FWIW i did some tests and I don't see noclone affecting frame pointer
with gcc 8. The only thing I saw was that empty functions ended up
without frame pointer.

I suspect you'll need to fix up the other users of noclone too.