in xgmii_mac PLL the power_down input has to be controllable according

libraries/io/tr_10GbE/tb/vhdl/tb_tr_10GbE.vhd

libraries/technology/10gbase_r/tb_tech_10gbase_r.vhd

libraries/technology/eth_10g/tb_tech_eth_10g.vhd

libraries/technology/pll/tech_pll_xgmii_mac_clocks.vhd