eselect-mesa sets the default 32bit sw rasterizer to gallium, which is correct, but sets the 64bit sw rasterizer to Classic, which prevents gnome-shell from starting. eselect-mesa should default both the 32bit and 64bit sw rasterizer to gallium.
I should have mentioned that this causes problems with gnome-shell when running gentoo as a virtualbox guest.
From [1]: > FWIW, softpipe is meant to be a reference implementation of a Gallium driver, it's not meant to be used for real world stuff [1] https://lists.freedesktop.org/archives/mesa-maintainers/2017-February/000053.html We should default to llvmpipe if present, then classic swrast, and basically never softpipe.
The bug has been closed via the following commit(s): https://gitweb.gentoo.org/repo/gentoo.git/commit/?id=2411166e56da41fc163475c0ce0f6c10310d6468 commit 2411166e56da41fc163475c0ce0f6c10310d6468 Author: Matt Turner <mattst88@gentoo.org> AuthorDate: 2018-05-27 06:51:04 +0000 Commit: Matt Turner <mattst88@gentoo.org> CommitDate: 2018-05-27 06:54:19 +0000 media-libs/mesa: Drop eselect-mesa support It only allowed selecting between two i915 drivers and two swrast drivers. Not interesting. Now, if gallium is enabled we will default to the gallium version of these drivers, otherwise the classic version. Closes: https://bugs.gentoo.org/546198 Closes: https://bugs.gentoo.org/576334 media-libs/mesa/mesa-18.1.0-r1.ebuild | 531 ++++++++++++++++++++++++++++++++++ media-libs/mesa/mesa-9999.ebuild | 43 +-- 2 files changed, 532 insertions(+), 42 deletions(-)