Completely disable any messages when booting Linux

I want to completely disable the output of any messages on the screen when the system boots. nomodeset, quiet - don't work properly for me. Error messages still appear. Ideally, I want to see a message on the monitor - "no signal". The best I've been able to achieve is setting console=ttyS0, but I'm not going to use the serial port. I tried to disable the framebuffer but that doesn't work either.