[OE-core] Use of multilib.conf taints hashes of -native recipes

[Khem Raj]

On Thu, 2019-12-12 at 16:05 +0000, Mike Crowe via Openembedded-core
wrote:
> We compile for a variety of machines, some of which require
> multilib.conf
> and some that do not. I was surprised to discover when switching
> between
> machines that the do_populate_sysroot_setscene tasks run for many
> -native
> recipe. :(
> 
> It looks like this is because RECIPE_SYSROOT changes:
> 
>  Variable RECIPE_SYSROOT value changed from '${WORKDIR}/recipe-
> sysroot' to '${WORKDIR}/${MLPREFIX}recipe-sysroot'
> 
> This problem goes away if I add the following line to native.bbclass:
> 
>  RECIPE_SYSROOT = "${WORKDIR}/recipe-sysroot"
> 
> but this feels like I'm solving the problem in the wrong place. Would
> it be
> better to modify multilmultilib.confib.conf to say something like:
> 
>  RECIPE_SYSROOT_class-target = "${WORKDIR}/${MLPREFIX}recipe-sysroot"
> 
> instead? (Although I'm rather worried that this will stop it actually
> working.)

in multilib.conf if we do

RECIPE_SYSROOT = "${WORKDIR}/${MLPREFIX}recipe-sysroot"
RECIPE_SYSROOT_class-native = "${WORKDIR}/recipe-sysroot"

might be better, since cross etc might still need it to differentiate
multilibs

other option could be to vardepexclude it for native recipes

I was also wondering if the defaults in bitbake.conf should use
MLPREFIX unconditionally and be removed from here.

> 
> Thanks.
> 
> Mike.