Title: New 17.0 profiles in the Gentoo repository
Author: Andreas K. Hüttel <firstname.lastname@example.org>
We have just added (for all arches except arm and mips, these follow
later) a new set of profiles with release version 17.0 to the Gentoo
repository. These bring three changes:
1) The default C++ language version for applications is now C++14.
This change is mostly relevant to Gentoo developers. It also
means, however, that compilers earlier than GCC 6 are masked
and not supported for use as a system compiler anymore. Feel
free to unmask them if you need them for specific applications.
2) Where supported, GCC will now build position-independent
executables (PIE) by default. This improves the overall
security fingerprint. The switch from non-PIE to PIE binaries,
however, requires some steps by users, as detailed below.
3) Up to now, hardened profiles were separate from the default
profile tree. Now they are moving into the 17.0 profile
as a feature there, similar to "no-multilib" and "systemd".
Please migrate away from the 13.0 profiles within the six weeks after
GCC 6.4.0 has been stabilized on your architecture. The 13.0 profiles
will be deprecated then and removed in half a year.
If you are not already running a hardened setup with PIE enabled, then
switching the profile involves the following steps:
If not already done,
* Use gcc-config to select gcc-6.4.0 or later as system compiler
* Re-source /etc/profile:
* Re-emerge libtool
emerge -1 sys-devel/libtool
* Select the new profile with eselect
* Re-emerge, in this sequence, gcc, binutils, and glibc
emerge -1 sys-devel/gcc:6.4.0
emerge -1 sys-devel/binutils
emerge -1 sys-libs/glibc
* Rebuild your entire system
emerge -e @world
Switching the profile from 13.0 to 17.0 modifies the settings of
GCC 6 to generate PIE executables by default; thus, you need to do
the rebuilds even if you have already used GCC 6 beforehand.
If you do not follow these steps you may get spurious build
failures when the linker tries unsuccessfully to combine non-PIE
and PIE code.