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raspberrypi, raspberrypi2: add a serial console

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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>
This commit is contained in:
Luca Ceresoli 2016-04-17 23:45:46 +02:00 committed by Thomas Petazzoni
parent 85f2e13c63
commit 20878a1017
4 changed files with 12 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

9
board/raspberrypi/post-build.sh Executable file
View File

@ -0,0 +1,9 @@
#!/bin/sh
set -u
set -e
# Add a console on tty1
grep -qE '^tty1::' ${TARGET_DIR}/etc/inittab || \
sed -i '/GENERIC_SERIAL/a\
tty1::respawn:/sbin/getty -L tty1 0 vt100 # HDMI console' ${TARGET_DIR}/etc/inittab

2
configs/raspberrypi2_defconfig
View File

@ -5,7 +5,6 @@ BR2_ARM_FPU_NEON_VFPV4=y
BR2_TOOLCHAIN_BUILDROOT_CXX=y
BR2_TARGET_GENERIC_GETTY_PORT="tty1"
BR2_SYSTEM_DHCP="eth0"
# Linux headers same as kernel, a 4.1 series
@ -33,4 +32,5 @@ BR2_PACKAGE_HOST_MTOOLS=y
BR2_TARGET_ROOTFS_EXT2=y
BR2_TARGET_ROOTFS_EXT2_4=y
# BR2_TARGET_ROOTFS_TAR is not set
BR2_ROOTFS_POST_BUILD_SCRIPT="board/raspberrypi2/post-build.sh"
BR2_ROOTFS_POST_IMAGE_SCRIPT="board/raspberrypi2/post-image.sh"

2
configs/raspberrypi_defconfig
View File

@ -2,7 +2,6 @@ BR2_arm=y
BR2_arm1176jzf_s=y
BR2_ARM_EABIHF=y
BR2_TARGET_GENERIC_GETTY_PORT="tty1"
BR2_SYSTEM_DHCP="eth0"
# Linux headers same as kernel, a 4.1 series
@ -32,4 +31,5 @@ BR2_PACKAGE_HOST_MTOOLS=y
BR2_TARGET_ROOTFS_EXT2=y
BR2_TARGET_ROOTFS_EXT2_4=y
# BR2_TARGET_ROOTFS_TAR is not set
BR2_ROOTFS_POST_BUILD_SCRIPT="board/raspberrypi/post-build.sh"
BR2_ROOTFS_POST_IMAGE_SCRIPT="board/raspberrypi/post-image.sh"

2
package/rpi-firmware/cmdline.txt
View File

@ -1 +1 @@
root=/dev/mmcblk0p2 rootwait
root=/dev/mmcblk0p2 rootwait console=tty1 console=ttyAMA0,115200