米尔科技bootdelay参数设置为0解决方案

    在使用MYD-AM3358开发板过程中把BootLoader里面的bootdelay参数设置为0后，不能进入到uboot的命令里面，不能烧写内核镜像到开发板上了……这怎么办呢？

先来看该启动日志：
U-Boot 2016.05 (Oct 23 2018 - 11:36:24 +0800)
       Watchdog enabled
I2C:   ready
DRAM:  512 MiB
NAND:  512 MiB
MMC:   OMAP SD/MMC: 0, OMAP SD/MMC: 1
Net:   Could not get PHY for cpsw: addr 0
cpsw
Hit any key to stop autoboot:  0 
switch to partitions #0, OK
mmc0 is current device
SD/MMC found on device 0
reading boot.scr
** Unable to read file boot.scr **
** Bad device specification 0x82000000 uEnv **
USB is stopped. Please issue 'usb start' first.
starting USB...
USB0:   scanning bus 0 for devices... 1 USB Device(s) found
       scanning usb for storage devices... 0 Storage Device(s) found
USB device 0: unknown device
switch to partitions #0, OK
mmc0 is current device
switch to partitions #0, OK
mmc0 is current device
SD/MMC found on device 0
switch to partitions #0, OK
mmc0 is current device
SD/MMC found on device 0
reading boot.scr
** Unable to read file boot.scr **
reading uEnv.txt
708 bytes read in 4 ms (172.9 KiB/s)
Loaded env from uEnv.txt
Importing environment from mmc ...
3471064 bytes read in 230 ms (14.4 MiB/s)
39405 bytes read in 26 ms (1.4 MiB/s)
Kernel image @ 0x82000000 [ 0x000000 - 0x34f6d8 ]
## Flattened Device Tree blob at 88000000
   Booting using the fdt blob at 0x88000000
   Loading Device Tree to 8fff3000, end 8ffff9ec ... OK
Fixing up ETH0 & ETH1 to CPSW Ethernet
Starting kernel ..

    看了完整的启动日志，我们可以使用下面的方法制作一个boot.scr文件，然后放到TF卡里面，再从TF卡启动。

1. 编写一个boot.cmd文本文件，内容如下
setenv bootdelay 2
saveenv
2. 制作一个boot.scr文件
mkimage -C none -A arm -T script -d boot.cmd boot.scr