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

[Richard Purdie]

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 multilib.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.)

I'm a little bit surprised we don't have tests which detect this. 

"oe-selftest -r ssstatetests"

should have something which detected this, at least from memory. Could
you take a look and see if we're missing some testcase?

You're right that we probably should do something fix this and I think
you are probably right about changing multiconfig.conf as above FWIW.

Cheers,

Richard