Linux 2.6.18 cannot boot in TMS320DM6467

Hello, everyone.
I am trying to use a 3G (WCDMA) communication module mounted to a TI TMS320DM6467 media processor. The single board computer is SEED-DVS6447 provided by Beijing Arrow SEED Technology Co.,Ltd. The OS provided by the producer is Linux 2.6.10 and do not support "USB driver for GSM and CDMA modems". So I have to migrate Linux 2.6.18 to this EVM board.
I downloaded the Linux 2.6.18 kernel from TI and built it successfully. The EVM board was set to boot from a piece of nor flash with a jffs2 root file system. The environment parameters of U-boot was set to

"mem=60M console=ttyS0,115200n8 root=/dev/mtdblock3 rootfstype=jffs2 noinitrd rw ip=192.168.253.140:192.168.253.142:192.168.253.1:255.255.255.0 video=dm64xxfbutput=pal"

The original Linux 2.6.10 provided by the producer can boot with the aforementioned envrionment parameters successfully. But the boot process of the new kernel failed, the boot information was as follows:

## Booting image at 80800000 ...
Image Name: Linux-2.6.18_pro500-davinci_evm-
Image Type: ARM Linux Kernel Image (uncompressed)
Data Size: 1442304 Bytes = 1.4 MB
Load Address: 80008000
Entry Point: 80008000
Verifying Checksum ... OK
OK

Starting kernel ...

Uncompressing Linux............................................................................................... ... done, booting the kernel.
Linux version 2.6.18_pro500-davinci_evm-arm_v5t_le (root@localhost.localdomain) (gcc version 4.2.0 (MontaVista 4.2.0-16.0.32.0801914 2008-08-30)) #1 PREEMPT Sun Dec 21 15:32:07 CST 2014
CPU: ARM926EJ-S [41069265] revision 5 (ARMv5TEJ), cr=00053177
Machine: DaVinci DM6467 EVM
Memory policy: ECC disabled, Data cache writeback
DaVinci DM6467 variant 0x0
CPU0: D VIVT write-back cache
CPU0: I cache: 16384 bytes, associativity 4, 32 byte lines, 128 sets
CPU0: D cache: 8192 bytes, associativity 4, 32 byte lines, 64 sets
Built 1 zonelists. Total pages: 15360
Kernel command line: mem=60M console=ttyS0,115200n8 root=/dev/mtdblock3 rootfstype=jffs2 noinitrd rw ip=192.168.253.140:192.168.253.142:192.168.253.1:255.255.255.0 video=dm64xxfbutput=pal
PID hash table entries: 256 (order: 8, 1024 bytes)
Clock event device timer0_0 configured with caps set: 03
Console: colour dummy device 80x30
Dentry cache hash table entries: 8192 (order: 3, 32768 bytes)
Inode-cache hash table entries: 4096 (order: 2, 16384 bytes)
Memory: 60MB = 60MB total
Memory: 57728KB available (2449K code, 527K data, 152K init)
Mount-cache hash table entries: 512
CPU: Testing write buffer coherency: ok
NET: Registered protocol family 16
DaVinci: 48 gpio irqs
ch0 default output "COMPOSITE", mode "NTSC"
ch1 default output "", mode ""
SCSI subsystem initialized
usbcore: registered new driver usbfs
usbcore: registered new driver hub
NET: Registered protocol family 2
IP route cache hash table entries: 512 (order: -1, 2048 bytes)
TCP established hash table entries: 2048 (order: 1, 8192 bytes)
TCP bind hash table entries: 1024 (order: 0, 4096 bytes)
TCP: Hash tables configured (established 2048 bind 1024)
TCP reno registered
Enabling VLYNQ clock
Enable VLYNQ Switch using I2C...
JFFS2 version 2.2. (C) 2001-2006 Red Hat, Inc.
io scheduler noop registered
io scheduler anticipatory registered (default)
Serial: 8250/16550 driver $Revision: 1.90 $ 2 ports, IRQ sharing disabled
serial8250.0: ttyS0 at MMIO map 0x1c20000 mem 0xfec20000 (irq = 40) is a ST16654
serial8250.0: ttyS1 at MMIO map 0x1c20400 mem 0xfec20400 (irq = 41) is a ST16650V2
serial8250 serial8250.0: unable to register port at index 2 (IO0 MEM1c20800 IRQ42): -28
RAMDISK driver initialized: 1 RAM disks of 8192K size 1024 blocksize
netconsole: not configured, aborting
Linux video capture interface: v2.00
i2c /dev entries driver
usbmon: debugfs is not available
Initializing USB Mass Storage driver...
usbcore: registered new driver usb-storage
USB Mass Storage support registered.
usbcore: registered new driver usbhid
drivers/usb/input/hid-core.c: v2.6:USB HID core driver
musb_hdrc: version 6.0, cppi-dma, host, debug=0
musb_hdrc: USB Host mode controller at c4050000 using DMA, IRQ 13
musb_hdrc musb_hdrc: MUSB HDRC host driver
musb_hdrc musb_hdrc: new USB bus registered, assigned bus number 1
usb usb1: configuration #1 chosen from 1 choice
hub 1-0:1.0: USB hub found
hub 1-0:1.0: 1 port detected
mice: PS/2 mouse device common for all mice
IPv4 over IPv4 tunneling driver
TCP bic registered
NET: Registered protocol family 1
NET: Registered protocol family 17
Time: timer0_1 clocksource has been installed.
Clock event device timer0_0 configured with caps set: 08
Switched to high resolution mode on CPU 0
IP-Config: No network devices available.
mounting information /dev/mtdblock3...
devname is mtdblock3,0
ROOT_DEV=0
Root-NFS: No NFS server available, giving up.
VFS: Unable to mount root fs via NFS, trying floppy.
No filesystem could mount root, tried: jffs2
Kernel panic - not syncing: VFS: Unable to mount root fs on unknown-block(2,0)

The information in red was added by me to debug the kernel. The major reason of the failure was that the dev_t in init/do_mount.c was 0. As a result, the kernel tried to boot in NFS mode and failed too.

How to solve this problem? Maybe I have to configure the kernel with “make menuconfig” or modify the source code of the kernel. I also tried to load the ,config file of Linux 2.6.10 but it did not work. Can anybody give some advices or references?
Thanks very much.

Kernel command line: mem=60M console=ttyS0,115200n8 root=/dev/mtdblock3 rootfstype=jffs2 noinitrd rw ip=192.168.253.140:192.168.253.142:192.168.253.1:255.255.255.0

That option is not working. You are brave trying this; I have a Rockwell tablet here that I would like to root, but it has some proprietary modules in it's kernel and I wouldn't dare change versions because I don't have source code for them.