How to redirect kernel messages to serial console

Feb 10, 2010 2 Replies

Hi, I am trying to redirect kernel message to serial console.



I am trying to modify LCD device driver for cirrus EP9307 board. We are using 2.6.8.1 kernel and reboot as bootloader.


I have enabled support for serial console in kernel config using menuconfig. The default console is set to tty0 which is lcd in our case. How can i change this to ttys0(uart1).


On net there is some information about changing this using kernel parameters.


In our system reboot unzips the kernel image and loads it.


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  • Ethernet eth0: MAC address 00:00:00:00:68:34 IP: 192.168.254.10

0/255.255.255.0, Gateway: 192.168.254.254 Default server: 192.168.254.254, DNS server IP: 192.168.254.254

RedBoot(tm) bootstrap and debug environment [ROMRAM] Non-certified release, version v2_0 - built 10:15:31, Feb 5 2010



Platform: Cirrus Logic EDB9307 Board (ARM920T) Rev A Copyright (C) 2000, 2001, 2002, Red Hat, Inc.



RAM: 0x00000000-0x04000000, 0x00041f68-0x03fbd000 available FLASH: 0x60000000 - 0x62000000, 128 blocks of 0x00040000 bytes each. == Executing boot script in 1.000 seconds - enter ^C to abort



RedBoot> fis load ramdisk.gz



RedBoot> fis load zImage



RedBoot> exec -r 0x800000 -s 0xC00000 Using base address 0x0008



0000 and length 0x0012f580

Uncompressing Linux......................................... ........................................... done, booting the kern el.


Please press Enter to activate this console.


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cheers



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tamamontu wibbled on Wednesday 10 February 2010 05:15

You'll need to append this to the boot loader line:

console=ttyS0,9600

or variations on that (9600 is the baud rate and ttyS0 is the device name - this could be something else on your setup)

More info here:

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tamamontu wibbled on Wednesday 10 February 2010 05:15

I'll also add - make sure console over serial is enabled in your kernel build.

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