$ sudo emerge -av =www-client/firefox-24.1.1 These are the packages that would be merged, in order: Calculating dependencies... done! [ebuild U ~] dev-libs/nspr-4.10.2 [4.10] USE="-debug" 1,078 kB [ebuild U ~] dev-libs/nss-3.15.3 [3.15.2] USE="-utils" 6,142 kB [ebuild U ~] www-client/firefox-24.1.1 [17.0.9] USE="alsa bindist dbus jit libnotify minimal -custom-cflags -custom-optimization -debug -gstreamer (-pgo) -pulseaudio% (-selinux) -startup-notification -system-cairo% -system-icu% -system-jpeg% -system-sqlite -wifi" LINGUAS="-af -ak -ar -as -ast -be -bg -bn_BD -bn_IN -br -bs -ca -cs -csb -cy -da -de -el -en_GB -en_ZA -eo -es_AR -es_CL -es_ES -es_MX -et -eu -fa -fi -fr -fy_NL -ga_IE -gd -gl -gu_IN -he -hi_IN -hr -hu -hy_AM -id -is -it -ja -kk -km -kn -ko -ku -lg -lt -lv -mai -mk -ml -mr -nb_NO -nl -nn_NO -nso -or -pa_IN -pl -pt_BR -pt_PT -rm -ro -ru -si -sk -sl -son -sq -sr -sv_SE -ta -ta_LK -te -th -tr -uk -vi -zh_CN -zh_TW -zu" 117,062 kB Total: 3 packages (3 upgrades), Size of downloads: 124,281 kB The following keyword changes are necessary to proceed: (see "package.accept_keywords" in the portage(5) man page for more details) # required by www-client/firefox-24.1.1 # required by @selected # required by @world (argument) =dev-libs/nspr-4.10.2 ~amd64 # required by =www-client/firefox-24.1.1 (argument) =www-client/firefox-24.1.1 ~amd64 # required by www-client/firefox-24.1.1 # required by @selected # required by @world (argument) =dev-libs/nss-3.15.3 ~amd64 Use --autounmask-write to write changes to config files (honoring CONFIG_PROTECT). Carefully examine the list of proposed changes, paying special attention to mask or keyword changes that may expose experimental or unstable packages. $ sudo emerge -av =www-client/firefox-24.1.1 --autounmask=n !!! Repository 'my_local_overlay' is missing masters attribute in '/home/alexander/gentoo/local_portage/metadata/layout.conf' !!! Set 'masters = gentoo' in this file for future compatibility !!! Repository 'games' is missing masters attribute in '/var/lib/layman/games/metadata/layout.conf' !!! Set 'masters = gentoo' in this file for future compatibility * IMPORTANT: 4 news items need reading for repository 'gentoo'. * Use eselect news to read news items. These are the packages that would be merged, in order: Calculating dependencies... done! !!! All ebuilds that could satisfy "=www-client/firefox-24.1.1" have been masked. !!! One of the following masked packages is required to complete your request: - www-client/firefox-24.1.1::gentoo (masked by: ~amd64 keyword) For more information, see the MASKED PACKAGES section in the emerge