Sent: Wednesday, January 22, 2020 at 1:53 AM
From: "Gerd Hoffmann" <kraxel@redhat.com>
To: "john brown" <john.brown8943k@mail.com>
Cc: seabios@seabios.org
Subject: Re: [SeaBIOS] does sercon-port support for memory mapped MMIO 32bit address?

Hi,

> But I can't turn on the  sercon port for boot menu. Seems that address for
> sercon is u16, only take 16bit address. I use 16bit serial port address
> for coreboot 0x3e8, it is not working.
>
> How to turn on MMIO serial console for boot menu?

Not supported right now. Needs non-trivial changes, sercon code might
have to switch to 32bit mode for mmio access, the registers are
out-of-reach in real mode.

cheers,
Gerd