raspberrypi, raspberrypi2: add a serial console
The current Buildroot defconfigs for Raspberry Pi and Raspberry Pi 2
instantiate a console on tty1, which appears on HDMI. Add a console on
the serial port (ttyAMA0) to be more consistent with other defconfigs
and provide a better out-of-the-box experience to users used to have a
serial console from Buildroot defconfigs.
This requires three changes:
1. have two 'console=' entries in the kernel command line: tty1,
then ttyAMA0;
2. change BR2_TARGET_GENERIC_GETTY_PORT to "console", so it starts
a getty on the last console= passed to the kernel, ttyAMA0;
3. add a new getty on tty1 to the generated inittab.
Step 2 is actually obtained by removing BR2_TARGET_GENERIC_GETTY_PORT
entirely from the defconfigs, since "console" is the default value.
Step 3 requires a post-build script since the Buildroot makefiles can
configure only one console.
Note: instead of simply adding a new getty on ttyAMA0 (which would
work) this patch actually changes BR2_TARGET_GENERIC_GETTY_PORT to
instantiate a console on UART, then adds back tty1 via
post-build.sh. This is done only to avoid the "GENERIC_SERIAL" comment
where we instantiate an HDMI console, then instantiate a really-serial
console on another line.
The result is these two inittab lines:
console::respawn:/sbin/getty -L console 0 vt100 # GENERIC_SERIAL
tty1::respawn:/sbin/getty -L tty1 0 vt100 # HDMI console
Cc: Yann E. MORIN <yann.morin.1998@free.fr>
Cc: Arnout Vandecappelle <arnout@mind.be>
Signed-off-by: Luca Ceresoli <luca@lucaceresoli.net>
Reviewed-by: "Yann E. MORIN" <yann.morin.1998@free.fr>
Signed-off-by: Thomas Petazzoni <thomas.petazzoni@free-electrons.com>
Luca Ceresoli