Serial console only works after reboot?

[Bruce Evans]

On Mon, 5 Jan 2004, Bruce M Simpson wrote:

> On Mon, Jan 05, 2004 at 04:50:13PM +1100, Bruce Evans wrote:
> > It should use BOOT_COMCONSOLE_PORT and BOOT_CONSOLE_SPEED like boot2
> > does.
>
> Ideally, yes. However an assembly language macro would be needed to stuff
> the appropriate divisor value into the BIOS call used to set the speed. There
> are hardly any bytes free in boot0; I had to shave strings to get enough
> space as it is.

There are also hardly enough bits in the BIOS interface.  It has a whole
3 bits to encode the speed and is limited to 9600 bps.

> Doing sio directly bypassing the BIOS would require that the MBR be enlarged
> to 1024, rather than 512, bytes. This is one of the issues I originally had
> with the code being imported as-is however obrien was happy to take it anyway.

Probably, but direct access only takes a few more bytes (20-30 altogether).
A feature could be left out to make room.  (The boot0 that I use has a
completely different feature set.)

Bruce