PPC440epx boot problem

[awang5907]

I am using linux kernel 2.6.30.4. I encounter 2 problems:
1. After console_init() is called inside start_kernel(), the console starts printing garbage like:
Serial: 8250/16550 driver, 4 ports, IRQ sharing enabled
serial8250.0: ttyS0 at MMIO 0x1ef600300 (irq = 16) is a 16550A
������������������������������ ���������������������������� ��������������������������������� ������������������������������ �����������������.
2. It pakics when mounting the root file system(NFS):
(gdb) bt
#0 panic (fmt=0xc0290e94 "VFS: Unable to mount root fs on %s")
at kernel/panic.c:70
#1 0xc02d8ce0 in mount_block_root (name=0xc0290de4 "/dev/root", flags=0x8001)
at init/do_mounts.c:272
#2 0xc02d9084 in prepare_namespace () at init/do_mounts.c:415
#3 0xc02d81ec in kernel_init (unused=<value optimized out>) at init/main.c:885
#4 0xc000de60 in kernel_thread ()
There is a patch for Sequoia board to delete /chosen part in sequoia.dts, is /chosen required?
I am new to Linux. Thanks for helping me.

[awang5907]

My guess to the first problem is that the baudrate is incorrect. Who can tell me how to access the CPU serial configuration memory 0x1ef600300 in kernel. I have both GDB and BDI3000.Thanks.

[rohshall]

Can you try to boot up an initrd or initramfs root file system?
Trying out NFS at the start may be a bit overwhelming.

[awang5907]

I have tried initramfs. I use the following lines in a file named initramfs.txt to generate initramfs:
dir /dev 755 0 0
nod /dev/console 644 0 0 c 5 1
nod /dev/loop0 644 0 0 b 7 0
dir /bin 755 1000 1000
slink /bin/sh busybox 777 0 0
file /bin/busybox /home/awang/proj/linux-2.6.30.4/usr/busybox 755 0 0
dir /proc 755 0 0
dir /sys 755 0 0
dir /mnt 755 0 0
file /init /home/awang/proj/linux-2.6.30.4/usr/init.sh 755 0 0

init.sh:
#!/bin/sh

echo "Mounting process"
mount -t process /process /process

echo "Starting system loggers"
syslogd
klogd

echo "Configuring ethernet interface"
ifconfig eth0 192.168.0.195

echo "Starting inetd"
xinetd

#start a shell
busybox sh

My first question is where "dev/console" is connected to the real serial driver. Do I need to do it?

The second question is that init.sh does not work. According the kernel documentation, "/init" has to do the same thing as prepare_namespace() to mount the final root and exec one of the predefined init binaries. Can anyone give me an example of "/init"? I am overwhelmed.



c) using initramfs. The call to prepare_namespace() must be skipped.
This means that a binary must do all the work. Said binary can be stored
into initramfs either via modifying usr/gen_init_cpio.c or via the new
initrd format, an cpio archive. It must be called "/init". This binary
is responsible to do all the things prepare_namespace() would do.

To maintain backwards compatibility, the /init binary will only run if it
comes via an initramfs cpio archive. If this is not the case,
init/main.c:init() will run prepare_namespace() to mount the final root
and exec one of the predefined init binaries.

[acrux]

very often these boards work only with a patched kernels and specific uboot releases. You need to look for a specific delopment toolkit maybe from the board's constructor. Is this a development sample board?