Updating all Servers to the 13.0 (2013) Profile
Gentoo 10.0 to 13.0 profiles upgrade & server profiles going away
We’ve generated a new set of profiles for Gentoo installation. These are now called 13.0 instead of 10.0, e.g., „default/linux/amd64/10.0/desktop“ becomes „default/linux/amd64/13.0/desktop“.
Everyone should upgrade as soon as possible. This brings (nearly) no user-visible changes. Some new files have been added to the profile directories that make it possible for the developers to do more fine-grained use flag masking, and this formally requires a new profile tree with EAPI=5 (and a recent portage version, but anything since sys-apps/portage-22.214.171.124 should work and anything since sys-apps/portage-126.96.36.199 should be perfect).
Since the 10.0 profiles will be deprecated immediately and removed in a year, emerge will suggest a replacement on every run. I strongly suggest you just follow that recommendation.
One additional change has been added to the package: the „server“ profiles will be removed; they do not exist in the 13.0 tree anymore. If you have used a server profile so far, you should migrate to its parent, i.e. from „default/linux/amd64/10.0/server“ to „default/linux/amd64/13.0“. This may change the default value of some use-flags (the setting in „server“ was USE=“-perl -python snmp truetype xml“), so you may want to check the setting of these flags after switching profile, but otherwise nothing happens.
Source: the dilfridge blog