开发板启动不了。

开发板启动不了。串口终端信息为：
##### EmbedSky BIOS for SKY2440/TQ2440 #####
Press Space key to Download Mode !
Booting Linux ...
Copy linux kernel from 0x00200000 to 0x30008000, size = 0x00200000 ... Copy Kernel to SDRAM done,NOW, Booting Linux......
Uncompressing Linux.......................................................................................................... done, booting the kernel.
Linux version 2.6.13 (root@EmbedSky) (gcc version 3.4.5) #4 Fri Aug 7 22:01:14 CST 2009
CPU: ARM920Tid(wb) [41129200] revision 0 (ARMv4T)
Machine: TQ2440
ATAG_INITRD is deprecated; please update your bootloader.
Memory policy: ECC disabled, Data cache writeback
CPU S3C2440A (id 0x32440001)
BUG: mapping for 0x20000300 at 0xd0000000 overlaps vmalloc space
S3C2440: core 400.000 MHz, memory 100.000 MHz, peripheral 50.000 MHz
S3C2410 Clocks, (c) 2004 Simtec Electronics
CPU0: D VIVT write-back cache
CPU0: I cache: 16384 bytes, associativity 64, 32 byte lines, 8 sets
CPU0: D cache: 16384 bytes, associativity 64, 32 byte lines, 8 sets
Built 1 zonelists
Kernel command line: noinitrd root=/dev/mtdblock2 init=/linuxrc console=ttySAC0
irq: clearing pending ext status 00080000
irq: clearing subpending status 00000002
PID hash table entries: 512 (order: 9, 8192 bytes)
timer tcon=00500000, tcnt a2c1, tcfg 00000200,00000000, usec 00001eb8
Console: colour dummy device 80x30
Dentry cache hash table entries: 16384 (order: 4, 65536 bytes)
Inode-cache hash table entries: 8192 (order: 3, 32768 bytes)
Memory: 64MB = 64MB total
Memory: 61056KB available (2559K code, 1037K data, 176K init)
Mount-cache hash table entries: 512
CPU: Testing write buffer coherency: ok
NET: Registered protocol family 16
USB Power Control, (c) 2004 Simtec Electronics
S3C2440: Initialising architecture
S3C2440: IRQ Support
S3C2440: IRQ Support
S3C2440: Clock Support, UPLL 48.000 MHz
SCSI subsystem initialized
usbcore: registered new driver usbfs
usbcore: registered new driver hub
S3C2410 DMA Driver, (c) 2003-2004 Simtec Electronics
DMA channel 0 at c4800000, irq 33
DMA channel 1 at c4800040, irq 34
DMA channel 2 at c4800080, irq 35
DMA channel 3 at c48000c0, irq 36
NetWinder Floating Point Emulator V0.97 (double precision)
devfs: 2004-01-31 Richard Gooch (rgooch@atnf.csiro.au)
devfs: boot_options: 0x1
yaffs Aug  7 2009 21:34:45 Installing.
Initializing Cryptographic API
Console: switching to colour frame buffer device 64x30
S3C24X0 fb0: s3c2410fb frame buffer device initialize done
GPIO L3 bus interface for S3C2440, installed
S3C2410 RTC, (c) 2004 Simtec Electronics
s3c2410-rtc s3c2410-rtc: rtc disabled, re-enabling
TQ2440_backlight initialized
TQ2440_GPF initialized
TQ2440_leds initialized
TQ2440-Beep initialized
s3c24x0_serial0 at MMIO 0x50000000 (irq = 70) is a S3C2440
s3c24x0_serial1 at MMIO 0x50004000 (irq = 73) is a S3C2440
s3c24x0_serial2 at MMIO 0x50008000 (irq = 76) is a S3C2440
io scheduler noop registered
io scheduler anticipatory registered
io scheduler deadline registered
io scheduler cfq registered
RAMDISK driver initialized: 16 RAM disks of 4096K size 1024 blocksize
loop: loaded (max 8 devices)
nbd: registered device at major 43

但是轻轻碰一下2440芯片又可以接着启动，接着显示的串口终端信息为：
Linux video capture interface: v1.00
ovcamchip: v2.27 for Linux 2.6 : OV camera chip I2C driver
Uniform Multi-Platform E-IDE driver Revision: 7.00alpha2
ide: Assuming 50MHz system bus speed for PIO modes; override with idebus=xx
ide_s3c2440_init
ide0: S3C2410 IDE interface
S3C24XX NAND Driver, (c) 2004 Simtec Electronics
s3c2410-nand: mapped registers at c4880000
30 ns is too big for current clock rate 100000
s3c2410-nand: timing: Tacls 0ns, Twrph0 4294ns, Twrph1 0ns
NAND device: Manufacturer ID: 0xec, Chip ID: 0x76 (Samsung NAND 64MiB 3,3V 8-bit)
NAND_ECC_NONE selected by board driver. This is not recommended !!
Scanning device for bad blocks
Bad eraseblock 2903 at 0x02d5c000
Creating 3 MTD partitions on "NAND 64MiB 3,3V 8-bit":
0x00000000-0x00040000 : "EmbedSky_Board_uboot"
mtd: Giving out device 0 to EmbedSky_Board_uboot
0x00200000-0x00400000 : "EmbedSky_Board_kernel"
mtd: Giving out device 1 to EmbedSky_Board_kernel
0x00200000-0x03df8000 : "EmbedSky_Board_yaffs2"
mtd: Giving out device 2 to EmbedSky_Board_yaffs2
Initial TQ2440 TWO USB HOST Driver!
s3c2410-ohci s3c2410-ohci: S3C24XX OHCI
s3c2410-ohci s3c2410-ohci: new USB bus registered, assigned bus number 1
s3c2410-ohci s3c2410-ohci: irq 42, io mem 0x49000000
hub 1-0:1.0: USB hub found
hub 1-0:1.0: 2 ports detected
Initializing USB Mass Storage driver...
usbcore: registered new driver usb-storage
USB Mass Storage support registered.
usb 1-2: new full speed USB device using s3c2410-ohci and address 2
usb 1-2: device descriptor read/64, error -110
usb 1-2: device descriptor read/64, error -110
usb 1-2: new full speed USB device using s3c2410-ohci and address 3
usb 1-2: device descriptor read/64, error -110
usb 1-2: device descriptor read/64, error -110
usb 1-2: new full speed USB device using s3c2410-ohci and address 4
usb 1-2: device not accepting address 4, error -110
usb 1-2: new full speed USB device using s3c2410-ohci and address 5
usb 1-2: device not accepting address 5, error -110
usbcore: registered new driver usbhid
drivers/usb/input/hid-core.c: v2.01:USB HID core driver
usbcore: registered new driver ov511
drivers/usb/media/ov511.c: v1.64 for Linux 2.5 : ov511 USB Camera Driver
usbcore: registered new driver gspca
drivers/usb/media/gspca/gspca_core.c: gspca driver 00.60.00 registered
mice: PS/2 mouse device common for all mice
ts: Compaq touchscreen protocol output
TQ2440 TouchScreen successfully loaded
i2c /dev entries driver
s3c2440-i2c s3c2440-i2c: slave address 0x10
s3c2440-i2c s3c2440-i2c: bus frequency set to 390 KHz
s3c2440-i2c s3c2440-i2c: i2c-0: S3C I2C adapter
TQ2440-SD TQ2440-SD: powered down.
TQ2440-SD TQ2440-SD: initialisation done.
TQ2440 SOUND driver register
TQ2440 SOUND driver probe!
TQ2440 UDA1341 audio driver initialized
NET: Registered protocol family 2
TQ2440-SD TQ2440-SD: powered down.
IP route cache hash table entries: 1024 (order: 0, 4096 bytes)
TCP established hash table entries: 4096 (order: 3, 32768 bytes)
TCP bind hash table entries: 4096 (order: 2, 16384 bytes)
TCP: Hash tables configured (established 4096 bind 4096)
TCP reno registered
TCP bic registered
NET: Registered protocol family 1
NET: Registered protocol family 17
yaffs: dev is 32505858 name is "mtdblock2"
yaffs: Attempting MTD mount on 31.2, "mtdblock2"
block 2776 is bad
VFS: Mounted root (yaffs filesystem).
Mounted devfs on /dev
Freeing init memory: 176K
SIOCSIFADDR: No such device
SIOCGIFFLAGS: No such device
[31/Dec/1969:23:59:59 +0000]
Please press Enter to activate this console. boa: server version Boa/0.94.13
[31/Dec/1969:23:59:59 +0000] boa: server built Aug 19 2007 at 17:40:00.
[31/Dec/1969:23:59:59 +0000] boa: starting server pid=773, port 80

请问这是什么原因？

启动完成后如果碰一下2440芯片，串口终端会提示：TQ2440-SD TQ2440-SD: powered down.又是什么原因，谢谢。

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