[yocto] x86_64 kernel with i586 userland plus SDK?

[Richard Weinberger]

On Wed, Nov 28, 2018 at 9:42 AM Richard Purdie
<richard.purdie at linuxfoundation.org> wrote:
> The system can definitely do it, its just not something we tend to do
> very often so its not entirely clear the best way to do it.
>
> What may work is selecting the i586 tune from an x64-64 target machine?
>
> Copying qemux86-64.conf to qemux86-64-2.conf and changing it to have
> DEFAULTTUNE ?= "i586" did appear to start to build at least in a quick
> test here...

I went this approach for now.
That way I get i586 userland and an SDK with both 32bit and 64bit toolchains.
The SDK offers me multiple environment files to include.

What I don't understand right now is, how can i tell the kernel recipe
that it has
to use the 64bit toolchain to build the kernel?

Any hints?

-- 
Thanks,
//richard