Re: [PATCH 1/3] retpolines: Only enable retpoline when compiler support it

[Peter Zijlstra]

On Mon, Oct 29, 2018 at 11:55:04PM -0700, Zhenzhong Duan wrote:
> Since retpoline capable compilers are widely available, make
> CONFIG_RETPOLINE hard depend on it.
> 
> Change KBUILD to use CONFIG_RETPOLINE_SUPPORT to avoid conflict with
> CONFIG_RETPOLINE which is used by kernel.
> 
> With all that stuff, the check of RETPOLINE is changed to
> CONFIG_RETPOLINE.

So what happens when we select CONFIG_RETPOLINE but do not have
RETPOLINE_SUPPORT ? From a quick reading we'll silently build a
!retpoline kernel. I would expect a build failure.