Re: [ECOS] Re: Romboot in i386 (continued) - comms. problems

[Nick Garnett <nickg at redhat dot com>]

Gary Thomas <gthomas@redhat.com> writes:

> On 13-Aug-2001 Alex Lennon wrote:
> > Looking at these serial drivers it seems to me that somebody has implemented
> > a polled mode schema on both Rx and Tx. Could somebody tell me if this is
> > correct ?
> > 
> > If so, then before I dive straight in and rewrite the code, is there any
> > reason
> > I shouldn't just use the 16x5x drivers already in eCos ?
> > 
> 
> RedBoot can only use polled drivers and is not set up to use the "normal"
> serial I/O in eCos.
> 
> Perhaps it's just a matter of not using the FIFOs appropriately in the
> HAL [diag] polled routines?

Yep.

Alex, bear in mind that the rom boot stuff is very much a work in
progress. I only ever took it as far as entering ecos/Redboot before
being sidetracked onto something else. To be honest I'm surprised it
works at all in a real board, I only ever ran it on a simulator.

One part of the job that was never done is the setup of the on-board
devices from scratch. Much of this code still expects the devices to
have been initialized by the BIOS.

So I suspect that the serial devices are still in whatever mode they
come up in on reset. This almost certainly has the FIFOs
disabled. Adding code to fully initialize the devices, including
turning on the FIFOs, should make things work better.



-- 
Nick Garnett, eCos Kernel Architect
Red Hat, Cambridge, UK