Getting the kernel to let go of my UART!

[Hans Petter Selasky]

On 01/22/17 06:07, Dustin Marquess wrote:
> [Sorry if this is somewhat of a dupe, I have yet to find a solution]
>
> I've been running FreeBSD on my Pi 3s for a little over a month now,
> first using gonzo's SMP code + a home cross-compiled kernel, and then
> I moved to the HardenedBSD images.  All of them work great except one
> issue that's driving me nuts...
>
> The downside to the Pi 3 vs some other boards is that there's really
> only one UART tied to the GPIO pins.  I'm trying to feed my Pi 3 with
> a GPS board.
>
> 1st issue: The NMEA stream upsets U-boot.  Fine, compiled my own and
> that's "fixed".
>
> 2nd issue: Even with a USB keyboard attached and HDMI output
> connected, FreeBSD still wants to steal the first uart (ttyu0) as a
> console port.  I thought that would be fine as long as I use "-m -n
> -q" in the boot config to disable kernel output and then "conscontrol
> delete ttyu0".  Well, that KIND of works.  It seems to work fine when
> using 115200bps, but trying to change the baud rate to match the GPS
> unit doesn't seem to work at all, I'm guessing because it's still set
> as an available console?
>
> hint.uart.0.flags="0x0" doesn't work, as it still marks it as a
> console.  console="efi" seems to be the only setting that works,
> "vidconsole" and "nullconsole" both don't work.
>
> Is there a way to stop the kernel from trying to claim the UART as a console?

I think so, have a look in /etc/ttys and comment out the ttyu0 line.

--HPS