Is here way to have 9600+ serial console and see boot0 message?

[Warner Losh]

On Wed, Sep 5, 2018, 12:16 PM Dimitry Andric <dim at freebsd.org> wrote:

> On 5 Sep 2018, at 19:22, Lev Serebryakov <lev at FreeBSD.org> wrote:
> >
> > On 05.09.2018 20:19, Allan Jude wrote:
> >
> >>> I want to have my serial console 115200 (of course), *including* BIOS
> >>> redirection (which goes before boot0sio).
> >>>
> >>> But boot0sio supports only speeds up to 9600 (due to int 14h
> limitations).
> >>>
> >>> Is it possible to solve this clash somehow?
> >>
> >> /boot/loader reads /boot.config where you can put -S115200
> > I think, /boot/boot reads /boot.config, and it works for me.
> >
> > My question is somewhat more tricky: I have 115200 BEFORE boot0sio
> > (from BIOS) and I have 115200 AFTER boot0sio (from /boot/boot and
> > /boot/loader later). And I want to see "F1 / F2" boot selection from
> > boot0sio.
>
> Recompile stand/i386 with BOOT_BOOT0_COMCONSOLE_SPEED=115200, I would
> normally say, but apparently stand/i386/boot0 is limited to a maximum
> of 9600 baud.  This looks like a BIOS int 0x14 limitation. :(
>

Only way around this I know is to recede boot0sio to go right to the
uart...  I tried this years ago, but overflowed 512 limits...

Warner

>