x220 gb00s # umerge                                                                                                                                                                                                                          
 * Mounting 6144M of memory to /var/tmp/portage ...                                                                                                                                                                                    
 * running emerge -uDN @world                                                                                                                                                                                                                                                                                                                                                                                                                                                          │
 * IMPORTANT: 3 news items need reading for repository 'gentoo'.
 * Use eselect news read to view new items.
 
These are the packages that would be merged, in order:

Calculating dependencies... done!

[ebuild     U  ] dev-libs/lzo-2.10:2::gentoo [2.09:2::gentoo] USE="-examples -static-libs" ABI_X86="32 (64) (-x32)" 587 KiB
[ebuild     U  ] dev-ruby/test-unit-3.2.3-r1:2::gentoo [3.2.3:2::gentoo] USE="-doc {-test}" RUBY_TARGETS="ruby21 ruby22 ruby23 ruby24 (-ruby20%)" 0 KiB
[ebuild  N     ] x11-apps/xbacklight-1.2.1-r1::gentoo  0 KiB
[ebuild     U  ] xfce-base/garcon-0.6.0::gentoo [0.5.0-r2::gentoo] USE="(-debug%)" 500 KiB
[blocks B      ] x11-apps/xbacklight ("x11-apps/xbacklight" is blocking sys-power/acpilight-1.0)

Total: 4 packages (3 upgrades, 1 new), Size of downloads: 1,086 KiB
Conflict: 1 block (1 unsatisfied)

 * Error: The above package list contains packages which cannot be
 * installed at the same time on the same system.
 
 (x11-apps/xbacklight-1.2.1-r1:0/0::gentoo, ebuild scheduled for merge) pulled in by
    x11-apps/xbacklight required by (x11-base/xorg-x11-7.4-r2:0/0::gentoo, installed)
    
  (sys-power/acpilight-1.0:0/0::gentoo, installed) pulled in by
    sys-power/acpilight required by @selected                                                                                                                                                                                                │


For more information about Blocked Packages, please refer to the following
section of the Gentoo Linux x86 Handbook (architecture is irrelevant):

https://wiki.gentoo.org/wiki/Handbook:X86/Working/Portage#Blocked_packages
 * unmounting tmpfs ...