KCFLAGS
make ARCH=arm KCFLAGS=-DENV_DEBUG CROSS_COMPILE=aarch64-linux-gnu-
env/sf.c env_sf_save 加入调试信息
# saveenv
Saving Environment to SPI Flash... env_sf_save (1) spi_flash_erase (2) spi_flash_write is40000
Erasing SPI flash...Writing to SPI flash...done
OK