RPi 4 USB boot without SD card

I believe it should work on a USB 2 port without need for an SD card.

I have no idea.

My advice is always to try booting in the most supported way first - that is with PiOS on an SD card. That proves the Pi works. I've had a duff Pi4 board. I got it replaced.

Move on after that.

Boots fine from USB3 also

How to Boot Raspberry Pi 4 / 400 From a USB SSD or Flash Drive

Am 06.02.2023 um 10:23:58 Uhr schrieb tumppiw:

Although that article only show a method that needs an SD card - I currently don't have one.

Mine "cat /sys/firmware/devicetree/base/model" says Pi4 Model B, rev 1.5 booted straight from SSD on USB-3 port. Created bootable SSD (Samsung T7) with Raspberry pi imager. Al my other pi (4's and some 3's) work the same.

Am 06.02.2023 um 11:45:12 Uhr schrieb Joe:

I also did that, it still tries to boot from SD card.

My other Pi 3 B did directly boot from USB without modification.

Might be difficult. AFAIK, The inability to boot from USB might be due to bootloader being too old or boot order set to something not including USB boot. Kinda need to boot Linux from SD to fix either. Assuming it actually boots from SD, since as far as you've said, it's never booted from anything?

I guess it depends on what you mean by "it offers"? Again AFAIK, network boot is one option in the boot order. If enabled then it should work if you have the servers running.

Does a PI have some sort of flash RAM in it then that can emulate BIOS NVRAM?

I cant recall ever being able to do any of this except via the boot partition files on the SD card.

I assumed that USB disk boot was 'burned in' to the firmware.

Am 07.02.2023 um 12:30:27 Uhr schrieb Anssi Saari:

I bought it used on eBay. I never managed it to boot into an operating system.

I see options for DHCPv4 (including TFTP server address etc.) when I switch it on, but it doesn't seem to use DHCPv4 (I have it, but no DNS and no TFP options set).

Pi 4 has EEPROM which contains the boot firmware. If you can boot it (with an SD card perhaps) you can update the EEPROM to the latest version.

I'd guess some of the NVRAM settings can be written to the EEPROM, but not sure what does.

Pi 3 doesn't have an EEPROM. Some (but not all) versions of them have USB boot available in their revision of the boot ROM, and you can blow an e-fuse to (irreversibly) enable it.

Theo

Hang on..NVRAM *is* EEPROM...

Wow. Bit burn-your-bridges, that.

NVRAM is a high level concept. The implementation can be EEPROM, flash, FERAM, MRAM, battery-backed SRAM, memristors...

The RPi folks call it EEPROM. I haven't checked the part to confirm if it's actually EEPROM or some other tech.

(these days flash is generally cheaper than EEPROM, especially if you don't need single-byte write capability)

It's not so bad because it's a priority order. Normally boot just goes straight to the SD. If you enable USB boot, it tries that first before trying the SD. It's basically like your BIOS boot-order setting that you can only change once. Unless you're in the habit of having bootable drives in both SD and USB slots at the same time it shouldn't matter.

Theo