[gentoo-dev] Getting proper USE_EXPAND variable(s) for multilib

[Michał Górny]

Hello,

There is a fair interest in multilib and while still early, it would be
a good moment to decide on how USE flags to use for it.

The current attempts are mostly using USE=multilib which is not really
expressive and poor. What I would go for is a clear variable specifying
which targets package is built for.


This raises the following questions:

1) do we want the default ABI to be switchable?

2) do we want irrelevant ABIs to be visible to emerge users?

By 2) I mean: do we want the users to see stuff like:

  MULTILIB_ABIS="amd64_abi1 amd64_abi2 -amd64_abi3 (-ppc64_abi1)
    (-ppc64_abi2) (-ppc64_abi3) ..."

or just the relevant part.

To be honest, I don't know if there's other way to hide USE flags than
using USE_EXPAND_HIDDEN. If we want to use that, we'd have to split
the flags per-arch, i.e. have:

  MULTILIB_AMD64="abi1 abi2 abi3"
  MULTILIB_PPC64="abi1 abi2 abi3"

with appropriate USE_EXPAND_HIDDEN set by profiles.


What are your thoughts? Which arches would like to use multilib? What
names for ABIs do you suggest?

-- 
Best regards,
Michał Górny