sandbox reports access violation during unpack stage of the ebuild when /var/tmp/portage is a symlink to other place[X]. To solve the problem I did: rm -f /var/tmp/portage mkdir /var/tmp/portage mount -o bind X /var/tmp/portage This is just a workaround, I think sandbox should handle this internaly.
You shouldn't create a symlink, but set the PORTAGE_TMPDIR env var to /somewhere/place/tmp instead of /var/tmp. The sandbox handles that.