Booting a Raspberry Pi from USB (was: Re: Is it a brick?)

[Oliver Grawert]

hi,
Am Montag, dem 11.10.2021 um 20:28 +0200 schrieb Liam Proven:
> 
> OK, this is tricky. Multiple things to possibly go wrong here.
> 
> [1] Raspberry Pis aren't PCs. They're ARM machines with a RISC chip.
> I
> don't even know if they have the same endian-ness as PCs.
they do have the same endianess (little) ... and to my knowledge they
are ARM only, i dont think there is any RISC involved ...
> 
> I'd stick to dd for that, ideally writing them _on_ a RasPi so you
> know everything matches.
> 
> [2] RasPis out of the box don't boot off USB and they have no CMOS,
> BIOS, or UEFI at all. The RasPi boot process is very complicated, in
> fact. That's why you can't simply put a boot manager (GRUB or
> something) onto the SD card and boot from that.
> 
The Pi4 comes with an EEPROM that allows direct booting from USB, but
you need to manually configure it first using the rpi-eeprom tool (not
sure why they picked that it defaults to SD-only boot, the EEPROM is
actually capable of probing USB by default and falling back to SD if
there is no USB2/3 disk attached ... perhaps because it makes the boot
half a second slower or some such ...)

https://ubuntu.com/tutorials/how-to-install-ubuntu-desktop-on-raspberry-pi-4?#4-optional-usb-boot

BTW, if you do not like the ads i found rpi-imager to be the far better
GUI for dd compared to balena etcher (just pick "local image" in the
list and it lets you select a random img file for writing)

ciao
	oli
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