我已经下载了源码，当编译时出现了这样的错误:

  @ubuntu:~/rk356x_linux5.10$  ./build.sh kernel

  processing option: kernel

  ============Start building kernel============

  TARGET_ARCH     =arm64
  TARGET_KERNEL_CONFIG =rockchip_linux_defconfig
  TARGET_KERNEL_DTS  =rk3566-evb2-lp4x-v10-linux
  TARGET_KERNEL_CONFIG_FRAGMENT =

  ==========================================

  #
  # No change to .config
  #
    CALL    scripts/atomic/check-atomics.sh
    CALL    scripts/checksyscalls.sh
    CHK    include/generated/compile.h
    LZ4C    arch/arm64/boot/Image.lz4

  Incorrect parameters
  Usage :
        lz4 [arg] [input] [output]
  input   : a filename
        with no FILE, or when  FILE is - or stdin, read standard input
  Arguments :
   -1    : Fast compression (default)
   -9   : High compression
   -d    : decompression (default for .lz4 extension)
   -z    : force compression
   -f   : overwrite output without prompting
   -h/-H  : display help/long help and exit

  arch/arm64/boot/Makefile:31: recipe for target 'arch/arm64/boot/Image.lz4'  failed

  make[2]: *** [arch/arm64/boot/Image.lz4] Error 1
  make[2]: *** Deleting file 'arch/arm64/boot/Image.lz4'
  arch/arm64/Makefile:170: recipe for target 'Image.lz4' failed
  make[1]: *** [Image.lz4] Error 2
  make[1]: *** Waiting for unfinished jobs....
  arch/arm64/Makefile:214: recipe for target 'rk3566-evb2-lp4x-v10-linux.img'  failed
  make: *** [rk3566-evb2-lp4x-v10-linux.img] Error 2
  ERROR: Running build_kernel failed!
  ERROR: exit code 2 from line 663:
      make ARCH=$RK_ARCH $RK_KERNEL_DTS.img -j$RK_JOBS
    

原因:  编译器lz4版本太低.
解决方案: 升级到V1.8.3以上版本.
lz4 -v            //查看编译器  lz4 版本
sudo cp out/host/linux-x86/bin/lz4 /usr/bin/lz   //从Android源码目录复制并覆盖编译器的lz4

当开发板内存高于4GB时，打开摄像头APP会出现异常。终端输出如下:

[  100.488782] rga_mm: RGA_MMU unsupported Memory larger than 4G!
[  100.488814] rga_mm: scheduler core[4] unsupported mm_flag[0x0]!
[  100.488821] rga_mm: rga_mm_map_buffer map dma_buf error!
[  100.488826] rga_mm: job buffer map failed!
[  100.488831] rga_mm: dst channel map job buffer failed!
[  100.488834] rga_mm: failed to map buffer
[  100.488842] rga_job: rga_job_commit: failed to map job info
[  100.488896] rga_job: request[1] task[0] job_commit failed.
[  100.488909] rga_job: rga request commit failed!
[  100.488915] rga: request[1] submit failed!

解决方案: 根据文件 ddr_than-4G.patch 修改源码并再次编译.

对于Linux系统，烧录镜像需要超级用户权限
1. 首先下载和解压 upgrade_tool .
2. 将固件和烧录工具 upgrade_tool 放在同一目录下.
3. 用USB OTG连接开发板和电脑, 按住开发板的recovery按键并上电, 数秒后松开按键.
4. 根据需要使用下面的命令烧写相应固件.

Basic Commands

  //List devices
  upgrade_tool ld   

  //Download boot
  upgrade_tool db rkxxloader.bin

  //Flash the partition table
  upgrade_tool di -p parameter.txt

  //Flash single partition image
  upgrade_tool di -k kernel.img

  //Falsh multiple partition images
  upgrade_tool di -u uboot.img -b boot.img

  //Flash the partition image with no defined abbreviation, you need to specify the partition name. 
  //Take the vendor partition as an example
  upgrade_tool di -vendor vendor.img

  //When ab partition are used, it also needs to be handled in undefined cases. 
  //Take boot_a and boot_b as example
  upgrade_tool di -boot_a boot.img -boot_b boot.img

  //Flash loader and reset
  upgrade_tool ul rkxxloader.bin  

  //Upgrade firmware and reset
  upgrade_tool uf update.img  

  //Erase device
  upgrade_tool ef rkxxloader.bin