我下载了github上的BSP源码编译后制作启动卡，但是kernel只有一下几行信息：
** Invalid boot device **
4.837][mmc]: blkcnt should not be 0
Loaded environment from uEnv.txt
Running uenvcmd ...
Banaan Pi bpi-m3 chip: a83t Service: linux
** Unable to read "bananapi/berryboot.img" from mmc 0:1 **
## Booting kernel from Legacy Image at 48000000 ...
Image Name: Linux-3.4.39-BPI-M3-Kernel
Image Type: ARM Linux Kernel Image (uncompressed)
Data Size: 6764496 Bytes = 6.5 MiB
Load Address: 40008000
Entry Point: 40008000
Verifying Checksum ... OK
Loading Kernel Image ... OK
OK
5.285][mmc]: MMC Device 2 not found
5.289][mmc]: mmc not find,so not exit
5.293]
Starting kernel ...
Booting Linux on physical CPU 0
[sun8i_fixup]: From boot, get meminfo:
Start: 0x40000000
Size: 2048MB
ion_carveout reserve: 96m 128m
ion_reserve_common: ion reserve: [0xb8000000, 0xc0000000]!
ion_cma reserve: 120m 176m 512m
ion_reserve_common: ion reserve: [0xa0000000, 0xc0000000]!
------sun8i_smp_init_ops----37-----
我换了一个android版本的uImage启动，是可以打印后面的信息的，所以肯定是printk被屏蔽掉了，请问在那里打开呢？我找了半天没找到