Avalon mm mapped slave, issue with read

Hi there, I am using the DE0 Nano Soc (cyclone V), I am abble to write data from HPS to FPGA using the avalon mm slave, but when I want to write from the fpga to HPS using the avalon mm slave, the HPS crash, indeed the linux terminal is blocked, I can write anithing on it.

I am using this simple code for the moment.

process(clock)

begin

if rising_edge(clock) then

if read = '1' then

readdata <= "10111010001100110011001100110000";

end if;

end if;

end process;

the same code but with a write condition works well.