Packages get masked for several reasons.
Portage uses Portage_Profiles, which are used to define basic system settings. Masking of packages also happens on a profile basis.
You can look at /usr/portage/profiles/package.mask/profile for example:
# Dev E. Loper <email@example.com> (28 Jun 2012) # Masking these versions until we can get the # v4l stuff to work properly again =media-video/mplayer-0.90_pre5 =media-video/mplayer-0.90_pre5-r1
First you see how added the mask, then an explanation why it was added followed by the masked package including version.
Now if you want to unmask one of those packages you have several possibilities to do so.
- Let emerge do it for you
# emerge --ask --autounmask-write =virtual/package-0.1.2 # dispatch-conf # emerge --ask =virtual/package-0.1.2
- doing it manually for a specific version
# mkdir -p /etc/portage # cd /etc/portage # echo "=virtual/package-0.1.2" >> /etc/portage/package.unmask
- manually for all versions
# echo "virtual/package" >> /etc/portage/package.unmask