I connected SDA3 (pin 24 on chestnut43 board) to WinXP hyperterminal, and booted up Overo.
I saw all booting messages are showing in hyperterminal.
-----------------------------------------------------------
Login timed out after 60 seconds.
.-------.
| | .-.
| | |-----.-----.-----.| | .----..-----.-----.
| | | __ | ---'| '--.| .-'| | |
| | | | | |--- || --'| | | ' | | | |
'---'---'--'--'--. |-----''----''--' '-----'-'-'-'
-' |
'---'
The Angstrom Distribution overo ttyS2
Angstrom 2010.7-test-20101005 overo ttyS2
overo login: root
| ' | | | |
'---'---'--'--'--. |-----''----''--' '-----'-'-'-'
-' |
'---'
The Angstrom Distribution overo ttyS2
Angstrom 2010.7-test-20101005 overo ttyS2
...
...
--------------------------------------------------------------------
Then, I run my program (written by Qt), the hyperterminal shows as follow:
--------------------------------------------------------------------------
QIODevice::read: Called with maxSize < 0
QIODevice::read: Called with maxSize < 0
QIODevice::read: Called with maxSize < 0
QIODevice::read: Called with maxSize < 0
QIODevice::read: Called with maxSize < 0
QIODevice::read: Called with maxSize < 0
QIODevice::read: Called with maxSize < 0
QIODevice::read: Called with maxSize < 0
QIODevice::read: Called with maxSize < 0
QIODevice::read: Called with maxSize < 0
QIODevice::read: Called with maxSize < 0
QIODevice::read: Called with maxSize < 0
QIODevice::read: Called with maxSize < 0
QIODevice::read: Called with maxSize < 0
...
...
-------------------------------------------------------------------------
in the meantime, the string which sent from Qt program also shows in the screen.
I only want ttyS2 send the information from my program, not other messages.
With help from Nabble forum, the following is my solution:
Those messages are from the kernel. U need to change the "console" uboot environment variable, otherwise the kernel will print messages on that serial port.
Take a look at uboot environment variable. to do this , boot gumsix, pushed any key to stop it booting from MMC. Then use "printenv" list all u-boot variables.
------------------------------------------
Overo # printenv
bootcmd=if mmc init; then if run loadbootscript; then run bootscript; else if run loaduimagei
baudrate=115200
loadaddr=0x82000000
console=ttyS2,115200n8
vram=12M
dvimode=1024x768MR-16@60
nandargs=setenv bootargs console=${console} vram=${vram} omapfb.mode=dvi:${dvimode} omapfb.d2
loadbootscript=fatload mmc 0 ${loadaddr} boot.scr
bootscript=echo Running bootscript from mmc ...; source ${loadaddr}
loaduimage=fatload mmc 0 ${loadaddr} uImage
mmcboot=echo Booting from mmc ...; run mmcargs; bootm ${loadaddr}
nandboot=echo Booting from nand ...; run nandargs; nand read ${loadaddr} 280000 400000; boot}
dieid#=0ef000040000000004035c140d002011
ethact=smc911x-0
bootdelay=2
defaultdisplay=lcd43
i2cspeed=3,100
bootargs=console=ttyS2,115200n8 i2c_bus=${i2cspeed} vram=12M omapfb.mode=dvi:1024x768MR-16@6t
mmcargs=setenv bootargs console=${console} i2c_bus=${i2cspeed} vram=12M omapfb.mode=dvi:1024t
stdin=serial
stdout=serial
stderr=serial
Environment size: 1279/131068 bytes
---------------------------------------------
the "console=ttyS2,115200n8" means send console login messages to ttyS2.
After that, take a look at /etc/inittab in mmc system on 2G SD card.
-------------------------------------------------
# /etc/inittab: init(8) configuration.
# $Id: inittab,v 1.91 2002/01/25 13:35:21 miquels Exp $
# The default runlevel.
id:5:initdefault:
# Boot-time system configuration/initialization script.
# This is run first except when booting in emergency (-b) mode.
si::sysinit:/etc/init.d/rcS
# What to do in single-user mode.
~~:S:wait:/sbin/sulogin
# /etc/init.d executes the S and K scripts upon change
# of runlevel.
#
# Runlevel 0 is halt.
# Runlevel 1 is single-user.
# Runlevels 2-5 are multi-user.
# Runlevel 6 is reboot.
l0:0:wait:/etc/init.d/rc 0
l1:1:wait:/etc/init.d/rc 1
l2:2:wait:/etc/init.d/rc 2
l3:3:wait:/etc/init.d/rc 3
l4:4:wait:/etc/init.d/rc 4
l5:5:wait:/etc/init.d/rc 5
l6:6:wait:/etc/init.d/rc 6
# Normally not reached, but fallthrough in case of emergency.
z6:6:respawn:/sbin/sulogin
S:2345:respawn:/sbin/getty 115200 ttyS2
# /sbin/getty invocations for the runlevels.
#
# The "id" field MUST be the same as the last
# characters of the device (after "tty").
#
# Format:
# :::
#
1:2345:respawn:/sbin/getty 38400 tty1
-------------------------------------------------------
The last line sets up a login on tty1. If you have a keyboard (eg. USB keyboard via a powered HUB) and display connected, then you'd be able to login using those. I am using a chestnut43 board with LCD, and i can use tty1 on a couple of occasions when I messed up the networking.
the command to change console environment variable are follows:
# setenv console tty1
# saveenv
The console setting is passed to the kernel at boot time. It Only tells the kernel where to send messages; It does not have anything to do with login terminals as that is handled by inittab and getty. I can use tty1 because it allows me to see the kernel messages on the LCD during boot.
