1 第一版硬件系统能起来。
2 第二版硬件起不来，典型问题如下：七八成启动到starting Kernel 卡死不动。有个别板子可以启动到系统后半段然后卡死或者崩掉。
3 两个版本的原理图只有一个LED灯的变化。
U-Boot 2013.01.01 (Apr 19 2016 - 11:09:14)
I2C: ready
DRAM: 512 MiB
WARNING: Caches not enabled
Lisa AM335x, with NO eeprom.
NAND: No NAND device found!!!
0 MiB
MMC: OMAP SD/MMC: 0, OMAP SD/MMC: 1
*** Warning - readenv() failed, using default environment
musb-hdrc: ConfigData=0xde (UTMI-8, dyn FIFOs, bulk combine, bulk split, HB-ISO Rx, HB-ISO Tx, SoftConn)
musb-hdrc: MHDRC RTL version 2.0
musb-hdrc: setup fifo_mode 4
musb-hdrc: 28/31 max ep, 16384/16384 memory
USB Peripheral mode controller at 47401000 using PIO, IRQ 0
musb-hdrc: ConfigData=0xde (UTMI-8, dyn FIFOs, bulk combine, bulk split, HB-ISO Rx, HB-ISO Tx, SoftConn)
musb-hdrc: MHDRC RTL version 2.0
musb-hdrc: setup fifo_mode 4
musb-hdrc: 28/31 max ep, 16384/16384 memory
USB Host mode controller at 47401800 using PIO, IRQ 0
Net: <ethaddr> not set. Validating first E-fuse MAC
cpsw, usb_ether
Hit any key to stop autoboot: 0
mmc0 is current device
SD/MMC found on device 0
reading uEnv.txt
** Unable to read file uEnv.txt **
reading uImage
2821400 bytes read in 297 ms (9.1 MiB/s)
Booting from mmc ...
## Booting kernel from Legacy Image at 80007fc0 ...
Image Name: Linux-3.2.0
Image Type: ARM Linux Kernel Image (uncompressed)
Data Size: 2821336 Bytes = 2.7 MiB
Load Address: 80008000
Entry Point: 80008000
Verifying Checksum ... OK
XIP Kernel Image ... OK
OK
Starting kernel ...
