I don’t know exactly how to change the default boot priority to SD card from EMMC storage.
mmc help from my serial terminal outputs
? - alias for 'help'
amlmmc - AMLMMC sub system
autoscr - run script from memory
base - print or set address offset
bdinfo - print Board Info structure
bmp - manipulate BMP image data
boot_cooling- cpu temp-system
booti - boot arm64 Linux Image image from memory
bootm - boot application image from memory
bootp - boot image via network using BOOTP/TFTP protocol
cbusreg - cbus register read/write
cfgload - read 'boot.ini' from FAT partiton
chipid - Print Chip ID
clkmsr - Amlogic measure clock
cmp - memory compare
cp - memory copy
cramfsload- load binary file from a filesystem image
cramfsls- list files in a directory (default /)
crc32 - checksum calculation
cvbs - CVBS sub-system
dcache - enable or disable data cache
defenv_reserv- reserve some specified envs after defaulting env
dhcp - boot image via network using DHCP/TFTP protocol
echo - echo args to console
emmc - EMMC sub system
env - environment handling commands
exit - exit script
ext2load- load binary file from a Ext2 filesystem
ext2ls - list files in a directory (default /)
ext4load- load binary file from a Ext4 filesystem
ext4ls - list files in a directory (default /)
ext4size- determine a file's size
false - do nothing, unsuccessfully
fastboot- use USB Fastboot protocol
fatinfo - print information about filesystem
fatload - load binary file from a dos filesystem
fatls - list files in a directory (default /)
fatsize - determine a file's size
fatwrite- write file into a dos filesystem
fdt - flattened device tree utility commands
get_rebootmode- get reboot mode
go - start application at address 'addr'
gpio - query and control gpio pins
gpt - GUID Partition Table
guid - GUID - generate Globally Unique Identifier based on random UUID
hdmitx - HDMITX sub-system
help - print command description/usage
i2c - I2C sub-system
icache - enable or disable instruction cache
img_osd - image osd sub-system
ini - parse an ini file in memory and merge the specified section into the env
itest - return true/false on integer compare
jtagoff - disable jtag
jtagon - enable jtag
ld_bl40 - load bl40 and run bl40.bin from bl33
load - load binary file from a filesystem
loadb - load binary file over serial line (kermit mode)
loadx - load binary file over serial line (xmodem mode)
loady - load binary file over serial line (ymodem mode)
loop - infinite loop on address range
ls - list files in a directory (default /)
macreg - ethernet mac register read/write/dump
md - memory display
mm - memory modify (auto-incrementing address)
mmc - MMC sub system
mmcinfo - display MMC info
movi - Read/write command from/to SD/MMC for ODROID board
mtest - simple RAM read/write test
mw - memory write (fill)
mwm - mw mask function
nm - memory modify (constant address)
oem - OEM sub system
open_scp_log- print SCP messgage
osd - osd sub-system
phyreg - ethernet phy register read/write/dump
ping - send ICMP ECHO_REQUEST to network host
printenv- print environment variables
pxe - commands to get and boot from pxe files
rarpboot- boot image via network using RARP/TFTP protocol
read_temp- cpu temp-system
reboot - set reboot mode and reboot system
reset - Perform RESET of the CPU
ringmsr - Amlogic measure ring
rpmb_state- RPMB sub-system
rsvmem - reserve memory
run - run commands in an environment variable
saradc - saradc sub-system
saradc_12bit- saradc sub-system
save - save file to a filesystem
saveenv - save environment variables to persistent storage
set_trim_base- cpu temp-system
set_usb_boot- set usb boot mode
setenv - set environment variables
showlogo- Displaying BMP logo file to HDMI screen with the specified resolution
showvar - print local hushshell variables
size - determine a file's size
sleep - delay execution for some time
source - run script from memory
sysboot - command to get and boot from syslinux files
systemoff- system off
tee_log_level- update tee log level
temp_triming- cpu temp-system
test - minimal test like /bin/sh
tftpboot- boot image via network using TFTP protocol
true - do nothing, successfully
unzip - unzip a memory region
usb - USB sub-system
usbboot - boot from USB device
uuid - UUID - generate random Universally Unique Identifier
version - print monitor, compiler and linker version
viu_probe- enable viu probe in no secure chip
vout - VOUT sub-system
vout2 - VOUT2 sub-system
vpp - vpp sub-system
vpu - vpu sub-system
write_trim- cpu temp-system
write_version- cpu temp-system