[meta-intel] [PATCH] intel-corei7-64: Add ttyS2 to console list

[VanCutsem, Geoffroy]

> -----Original Message-----
> From: meta-intel-bounces at yoctoproject.org [mailto:meta-intel-
> bounces at yoctoproject.org] On Behalf Of Patrick Ohly
> Sent: Wednesday, June 29, 2016 9:18 PM
> To: Saul Wold <sgw at linux.intel.com>
> Cc: meta-intel at yoctoproject.org; dvhart at linux.intel.com
> Subject: Re: [meta-intel] [PATCH] intel-corei7-64: Add ttyS2 to console list
> 
> On Wed, 2016-06-29 at 11:38 -0700, Saul Wold wrote:
> > This converts SERIAL_CONSOLE -> SERIAL_CONSOLES in order to add ttyS2
> > to the list of terminals that could be a console on intel-corei7
> > devices The Kernel cmdline is also updated to support ttyS2.
> >
> > NOTE: that SERIAL_CONSOLES will try to start a getty/login on each
> > device and if the tty device does not exist it may give a warning or
> > error at boot time, this warning/error is OK.
> >
> > Signed-off-by: Saul Wold <sgw at linux.intel.com>
> > ---
> >  conf/machine/intel-corei7-64.conf | 4 ++--
> >  1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/conf/machine/intel-corei7-64.conf
> > b/conf/machine/intel-corei7-64.conf
> > index 30d492f..5b7b62b 100644
> > --- a/conf/machine/intel-corei7-64.conf
> > +++ b/conf/machine/intel-corei7-64.conf
> > @@ -27,7 +27,7 @@ XSERVER ?= "${XSERVER_X86_BASE} \
> >             "
> >
> >  SYSLINUX_OPTS = "serial 0 115200"
> > -SERIAL_CONSOLE = "115200 ttyS0"
> > -APPEND += "rootwait console=ttyS0,115200 console=tty0"
> > +SERIAL_CONSOLES = "115200;ttyS0 115200;ttyS2"
> > +APPEND += "rootwait console=ttyS2,115200 console=ttyS0,115200
> console=tty0"
> 
> The kernel is limited to printing output on one console of each type. I can dig
> out the relevant kernel doc if you don't find it (would have to do some
> searching myself again).

I think this is what you referring to: https://www.kernel.org/doc/Documentation/serial-console.txt

More specifically:
You can specify multiple console= options on the kernel command line.
Output will appear on all of them. The last device will be used when
you open /dev/console. So, for example:

	console=ttyS1,9600 console=tty0

defines that opening /dev/console will get you the current foreground
virtual console, and kernel messages will appear on both the VGA
console and the 2nd serial port (ttyS1 or COM2) at 9600 baud.

Note that you can only define one console per device type (serial, video).

> 
> It's a bit fuzzy which one it picks from the command line (first or last). I
> thought it was the last, but with the Broxton kernel it happened to be the
> first one. So with the line above, kernel output goes to ttyS2 and tty0, which
> is probably not what you want on most generic
> intel-corei7-64 machines.

That indeed seems to be the opposite to what's described in the doc above...

Geoffroy