There are two reasons to use/power on Elbrus:

1) current kernels generate "button" event for ACPI
   power button press instead of "button/power";
   systemd doesn't grok that, and acpid needs special
   configuration to (which needs to be fixed properly
   in said kernels but just not done yet -- mcst#6148);

2) installer-feature-e2k-power is useful on e2kv6
   as it configures e2k-pcs-cpufreq to autoload.

See-also: http://www.gnu.org/software/make/manual/make.html#Double_002dColon

PS: e2k-pcs-cpufreq uses to be builtin, *argh*