Usage of RAM block as ROM

[PPlinux]

Dear,

is the a way using RAM (GHDL,VHDL -> Yosys) FPGA (onchip) blockRAM 521 words 16 bit as ROM ?
In Lattice ICE40 FPGA RAM could be preloaded during FPGA power on.

Hoping to receive some examples or advice, I meanwhile remain,

Patrick Pelgrims