Is it possible to flash the eMMC from SD memory card boot

Would it be possible to flash the eMMC on the Rock5B by first booting the Rock5B off an SD memory card with a live OS, and then attach the eMMC to the Rock5B PCB, and then use “dd” or other flash tool to flash the eMMC?

This would need the eMMC to be hotpluggable, perhaps by turning on/off some jumper while doing so.

Why not connect the eMMC before booting? You can just use dd to copy the system from SD then (remember to fix the partition size and the backup GPT using gparted before rebooting to eMMC).

@incognito But there is no button on the Rock5B to make it boot from the SD memory card - it will only boot from SD memory card if eMMC is not connected?

An alternative way to get the SBC to boot updated OS at all, is detach eMMC and this way it boots off SD, using SD as system disk.

Something must have changed then. For me the primary boot device is the SD card. Do you have the SPI flash memory zeroed?

Likely you have an image on the eMMC already? Its booting that when attached.
I got into the situation and its just a pain so I bought one of these from the store.
You shouldn’t attach eMMC when powered or at least I advise not to.

I did have one of the uSD emmc convertors but didn’t seem to work and the above makes things much easier.

Your board should have a MASKROM button. Keep that pressed while the board boots up. It will disable the eMMC