https://docs.amd.com/v/u/en-US/en154
Virtex-6 FPGA -1L Speed Grade LX75T, LX130T, LX195T, LX240T, LX365T, LX550T, LX760, SX315T, and...
EN154: Errata for the Virtex-6 FPGA -1L speed grade LX75T, LX130T, LX195T, LX240T, LX365T, LX550T, LX760, SX315T, and SX475T devices.