How to boot from USB?

[Arwen]

The booting is a bit complex, compared to x86/x64, as the x86/x64 BIOS hides a lot of the CPU booting issues. ARM & ARM64 don't have a standard BIOS, yet. We use U-Boot which is pretty primitive still, (though progressing).

So, the chip used in the Pinebook Pro is a Rockchip RK3399 SoC and only boots from specific devices, starting with the first. If that device does not have software loaded, then the CPU moves on to the next device. Here are the devices: SPI NOR, eMMC, SD & USB OTG. That USB OTG is NOT a normal boot. I don't understand it, but my understanding is that it won't boot a USB flash drive.

That leaves a Micro SD card as your best bet. If you don't have one, then you basically NEED one for any recovery.

However, the software in the SPI NOR or eMMC "may" allow booting to a normal USB flash drive. BUT, and be very clear it's a MAYBE, it's up to the software version loaded on SPI NOR or eMMC. (And then the distro on the USB flash drive needs to support USB too.) Booting off normal USB flash drives was a highly desired feature, and has been added to the U-Boot used on many Pinebook Pro Linux distros.

Eventually we will see better initial booting support. I have tested a version of U-Boot with more features, including NVMe support and boot time display menu, but it's not stable.