Re: Support for serial console on legacy free machines

[Johannes Erdfelt <jerdfelt@valinux.com>]

On Tue, Jul 31, 2001, Keith Owens <kaos@ocs.com.au> wrote:
> On Mon, 30 Jul 2001 16:40:31 -0600 (MDT), 
> Andreas Dilger <adilger@turbolinux.com> wrote:
> >What bothers me is that new systems don't have a serial port, and no ISA
> >slots, so there is no hope of getting a "serial console" support without
> >ACPI (which is rather heavyweight AFAIK).  USB is far too complex to use
> >for early-boot debugging, so what else is left?
> 
> I briefly discussed this with the USB maintainers at the 2.5 kernel
> developers conference.  They thought that a stripped down USB serial
> console was possible, without full USB support.  Is that still the
> case?

I think so. Keyboards have a nice feature called boot protocol mode
which is a dumbed down version for BIOS' and the like to use.

What would be needed is a driver for UHCI and OHCI does polling
exclusively, which isn't a big problem and only does control and
interrupt pipes.

I think this can be done with a minimal amount of code. It would
probably be smaller than Linus' original USB driver.

JE