Re: FTDI serial console support?

From: Andrew Worsley <amworsley@gmail.com>
To: The development of GNU GRUB <grub-devel@gnu.org>
Cc: dkiper@net-space.pl
Subject: Re: FTDI serial console support?
Date: Sat, 19 May 2018 23:12:42 +1000	[thread overview]
Message-ID: <CA+Y=x3=DYRZUcqpcp=O8nt-b4CdE8ytyNVLg+Pp1y-bmgQ-sRA@mail.gmail.com> (raw)
In-Reply-To: <20180518.163239.1042395263713665873.petter@gustad.com>

On 19 May 2018 at 00:32, Petter Gustad <grub@gustad.com> wrote:
> From: Daniel Kiper <dkiper@net-space.pl>
> Subject: Re: FTDI serial console support?
> Date: Fri, 18 May 2018 13:55:55 +0200
>
>> On Fri, May 18, 2018 at 01:01:41PM +0200, Petter Gustad wrote:
>>> From: Daniel Kiper <dkiper@net-space.pl>
>>> Subject: Re: FTDI serial console support?
>>> Date: Wed, 16 May 2018 11:32:19 +0200
>>>
>>> > On Wed, May 16, 2018 at 06:21:17AM +0200, Petter Gustad wrote:
>>> >> From: Daniel Kiper <dkiper@net-space.pl>
>>> >> Subject: Re: FTDI serial console support?
>>> >> Date: Tue, 15 May 2018 22:00:06 +0200
>>> >>
>>> >> > On Fri, May 11, 2018 at 03:55:36PM +0200, Petter Gustad wrote:
>>> >> >>
>>> >> >> Is there a way to specify a FTDI based serial console using
>>> >> >> GRUB_TERMINAL, GRUB_SERIAL_COMMAND, or some other variable? If yes,
>>> >> >> what is the syntax?
>>> >> >>
>>> >> >> BTW my serial port adapter matches the vendor id and device id given
>>> >> >> in grub-core/bus/usb/serial/ftdi.c:
>>> >> >>
....
>> Could you just do "insmod usbserial_ftdi"? There is a chance that it
>> will pull in all needed dependencies without breaking disk access.
>
> Thanks. Only "insmod usbserial_ftdi" does work in the sense that it
> will not break disk access. I also managed to load grub using PXE/tftp
> where I was not dependend upon disk access.
>
> But in both cases it does not work like in the coreboot URL above.
> After do insmod on usbserial_ftdi and usbserial_usbdebug the
> terminal_output command will only return console as its active output
> terminal. It will list serial_* as available output terminals, but I
> can't select usb0, usb1, etc as argument to the serial command.

I think GRUB relies on the BIOS/UEIF to provide drivers and typically
USB  was only
used to emulated old hardware like keyboard/mouse  and CD-ROMs.

Coreboot - is a BIOS/UEIF replacement and so it can do anything they
care to implement - but then it has to be
customised for each individual hardware case where as GRUB can rely on
the standardised routines.

But perhaps things have moved on - it would be great if UEIF provided
some standard USB drivers for serial.

Andrew