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 <[email protected]>

Cc Arnout Vandecappelle <[email protected]>

Signed-off-by Luca Ceresoli <[email protected]>

---

v2:
- remove BR2_TARGET_GENERIC_GETTY_PORT, it defaults to "console"
- rebase on current master

Tested on both Raspberry Pi B and Raspberry Pi 2, each on serial and HDMI console.

---
 board/raspberrypi/post-build.sh  | 9 +++++++++
 configs/raspberrypi2_defconfig   | 2 +-
 configs/raspberrypi_defconfig    | 2 +-
 package/rpi-firmware/cmdline.txt | 2 +-
 4 files changed, 12 insertions(+), 3 deletions(-)
 create mode 100755 board/raspberrypi/post-build.sh

board/raspberrypi/post-build.sh new file +9 -0

new file mode 100755
index 000000000000..7eae14a88569
@@ -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

configs/raspberrypi2_defconfig +1 -1

index 506330cd0780..7fc39c234c32 100644
@@ -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"

configs/raspberrypi_defconfig +1 -1

index 1795b2c03d53..8d13381105c1 100644
@@ -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"

package/rpi-firmware/cmdline.txt +1 -1

index 38aa3782621b..155a54693bff 100644
@@ -1 +1 @@
-root=/dev/mmcblk0p2 rootwait
+root=/dev/mmcblk0p2 rootwait console=tty1 console=ttyAMA0,115200

Signature · 1 line

1.9.1

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 <[email protected]>

Cc Arnout Vandecappelle <[email protected]>

Signed-off-by Luca Ceresoli <[email protected]>

---

Hello,

Quoted 35 lines · Luca Ceresoli

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 <[email protected]>

Cc Arnout Vandecappelle <[email protected]>

Signed-off-by Luca Ceresoli <[email protected]>

Quoted 1 line

---

Applied to master, thanks. Maybe this calls for an update of the RaspberryPi readme.txt file, to explicitly indicate that a getty will be running on both the HDMI/composite output *and* the serial port?