bob prohaska <
bp@www.zefox.net> wrote:
Is it possible (and useful) to update firmware on a Pi3B?
The Pi3B in question doesn't run RasPiOS normally. I'm
having some difficulties booting from USB and wonder if
any improvements exist. The OTP bit is confirmed set
but it doesn't detect one of my USB-SATA bridges, a
Sabrent EC-UASP. It's up-to-date per the Sabrent updater.
There's two parts to the firmware: the GPU firmware on the SD card and the firmware in the EEPROM.
On a Pi4, the EEPROM contains the first stage bootloader and then it fetches the rest from SD, USB, NVMe, network-boot, etc.
On a Pi3, the first stage bootloader is in ROM and can't be updated. So the first stage boot is fixed. It then loads GPU firmware from the boot device - SD, USB, PXE - and the GPU picks up from there.
(Pi1-Pi3 use the same ROM FSBL pattern, although it's been upgraded in each
new release)
If you can't get your Pi3 to read the USB then I'm not sure there's much you can do, because that's ROM firmware which can't be changed. You could put
an SD card in there just to hold the kernel and GPU firmware then put your
main FS on USB.
Theo
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