adoodle ~ # equery l nvidia
[ Searching for package 'nvidia' in all categories among: ]
 * installed packages
adoodle ~ #


adoodle ~ # emerge --tree -vp nvidia-legacy-drivers
>>> --pretend disables --ask... removing --ask from options.

These are the packages that would be merged, in reverse order:

Calculating dependencies... done!
[blocks B     ] x11-drivers/nvidia-legacy-drivers (is blocking x11-drivers/nvidia-drivers-1.0.9746)
[blocks B     ] x11-drivers/nvidia-drivers (is blocking x11-drivers/nvidia-legacy-drivers-1.0.7184)
[ebuild  N    ] x11-drivers/nvidia-legacy-drivers-1.0.7184  USE="dlloader" 5,450 kB
[ebuild  N    ] x11-drivers/nvidia-drivers-1.0.9746  USE="dlloader" 0 kB

Total: 2 packages (2 new, 2 blocks), Size of downloads: 5,450 kB



adoodle ~ # emerge nvidia-legacy-drivers

These are the packages that would be merged, in order:

Calculating dependencies... done!
[blocks B     ] x11-drivers/nvidia-legacy-drivers (is blocking x11-drivers/nvidia-drivers-1.0.9746)
[blocks B     ] x11-drivers/nvidia-drivers (is blocking x11-drivers/nvidia-legacy-drivers-1.0.7184)
[ebuild  N    ] x11-drivers/nvidia-legacy-drivers-1.0.7184  USE="dlloader" 5,450 kB
[ebuild  N    ] x11-drivers/nvidia-drivers-1.0.9746  USE="dlloader" 0 kB

Total: 2 packages (2 new, 2 blocks), Size of downloads: 5,450 kB

!!! Error: The above package list contains packages which cannot be installed
!!!        at the same time on the same system.

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

http://www.gentoo.org/doc/en/handbook/handbook-x86.xml?full=1#blocked