On Sun, 14 Jun 2015 19:22:14 +0000 (UTC) James wrote:
> Hello
> 
> Background:
> As a minimalist I'm trying to ferret out the differences in some of the more
> minimal profiles versus potential embedded profiles, across several
> different architectures: (arm32, arm64 x63_32 x86_64 ppc etc). I am also
> quite curious to find a tool that will clearly list the complete set of 
> packages a given (eselected) profile will yield and the best ways to
> customize that list of minimal (critical) packages.
> 
> 
> 
> So in /etc/portage/profiles, we have lots of good information. For example
> the 'base' dir currently lists 77 packages found in most profiles (?). The
> '/usr/portage/profiles/arch.list' dir lists not only the recognized arches
> but  also "Prefix Keywords". I'm not exactly sure how all of this profile 
> stuff works; who decides what's (packages) in and out, package_masks etc etc.
> 
> 
> So my questions related to how does gentoo actually determines the exact
> list of programs that are minimally installed, with the specific 
> arch and the profile selected? In previous times, I just put USE='-*' in the
> make.conf file and built upwards from there.

Profile do all the stuff that can be done or overridden
in /etc/portage, but they define some sane "default" sets of
settings for common profiles.

USE="-*" will override all USE settings in your profile. As you were
already warned, this may break stuff: e.g. expected
functionality will not be available or package will refuse to build
if it needs at least one of USE flags set (e.g. alternative foo
providers). So you must test things very carefully with USE="-*".

A set of default packages is defined in the "packages" file of each
profile. Profiles usually have "parent" file which lists parent
profiles: they are inherited, but may be overridden here and there
in a child profile. 

If you want an absolutely minimal system, after you have set it up
you may remove some packages even from the @system set. E.g. if
you're sure you don't need man or ssh, remove corresponding
packages. Just be careful here since it is easy to brick your
system here.

Best regards,
Andrew Savchenko