Linux on ML403 serial console problem

Anand Kumar S sanandkumar at
Thu Jul 3 20:12:21 EST 2008



I am using MVL 4.0.1 to boot on ML403 board. I have created the
xparameters.h file using EDK 10.1 and I was able to boot the kernel with
32 MB of memory and UART set as std 16550 uart.

Since this board came without sysace flash card I am using ramdisk
technique to boot linux. I created a small ramdisk with my test program
which sleeps for 10 seconds and prints a hello

world using printf. I modified kernel init/main.c to execute /bin/test
(my test program) from the RAMDISK. I created the ramdisk and appended
with zImage using make zImage.initrd command


I used dow method from xmd to download the zImage.initrd.elf on the
board and I was able to boot the board till the point of executing my
/bin/test. However I see that the print statements

from my test program are not coming on the serial port. I see that the
printf calls tty_io write and it goes to uart_write routine in
serial_core.c, however I am not able to see my prints on

the hyperterminal. I can see all the kernel printks except for this
printf statement from my user program. Also all the kernel printks seem
to call serial_8250_console write routine but the

user application seems to call the uart_write routine. Does someone have
any idea about what might be going wrong here? Is it something to do
with serial console settings ?


Any help is greatly appreciated as I am really struggling with this
problem for the past 3 days. Given below is the output from serial port.
I do not have FB support or VT or VT console

Support enabled. Only SERIAL console support is enabled i.e




Serial: 8250/16550 driver $Revision: 1.90 $ 5 ports, IRQ sharing

Registering platform device 'serial8250'. Parent at platform

ttyS0 at MMIO 0x0 (irq = 9) is a 16550A

io scheduler noop registered

io scheduler anticipatory registered

io scheduler deadline registered

io scheduler cfq registered

RAMDISK driver initialized: 16 RAM disks of 8192K size 1024 blocksize

loop: loaded (max 8 devices)

PPP generic driver version 2.4.2

PPP Deflate Compression module registered

NET: Registered protocol family 24

xemac 0: using fifo mode.

eth0: Xilinx EMAC #0 at 81000000 mapped to 0xC30C0000, irq=0

i2c /dev entries driver

xilinx_iic.0 #0 at 0x81600000 mapped to 0xC30E0000, irq=6

mice: PS/2 mouse device common for all mice

NET: Registered protocol family 2

IP: routing cache hash table of 512 buckets, 4Kbytes

TCP: Hash tables configured (established 2048 bind 4096)

NET: Registered protocol family 1

NET: Registered protocol family 17

interrupts enabled 

TX interrupts enabled. register baseaddr c30c0000 offset 7fc is 8 

TX interrupts enabled. register baseaddr c30c0000 offset ffc is 0 

RX interrupts enabled. register baseaddr c30c0000 offset 17fc is 9 

RX interrupts enabled. register baseaddr c30c0000 offset 1ffc is 0 

GIER interrupts enabled. register baseaddr c30c0000 offset 7f8 is

Sending DHCP requests .,... OK

IP-Config: Got DHCP answer from, my address is

IP-Config: Complete:

      device=eth0, addr=, mask=,

     host=,, nis-domain=(none),

     bootserver=, rootserver=, rootpath=

RAMDISK: Compressed image found at block 0

VFS: Mounted root (ext2 filesystem).

Freeing unused kernel memory: 124k init

done freeing memory. creating console 

console created 

running process /bin/test 

in tty_write

before calling write. buf contents h e l

core write

core write

core write

Kernel panic - not syncing: Attempted to kill init!

 <0>Rebooting in 180 seconds..<NULL>



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