SPI flash

[Zoltan Hoppar]

Hi,

I would like to know more about the SPI flash possibility, and how it
works. I will receive an Orange Pi Zero with expansion board, and seems to
me that SPI chip gonna help to boot easier... but - how works? Can be done
with Fedora too?

Thanks,

Zoltan

[Peter Robinson]

> I would like to know more about the SPI flash possibility, and how it works.
> I will receive an Orange Pi Zero with expansion board, and seems to me that
> SPI chip gonna help to boot easier... but - how works? Can be done with
> Fedora too?

It's not so much about Fedora rather u-boot and the flash itself. It's
generally useful to actually link to details of what you have in terms
of devices, there's lots of different configs so more details tends to
be better.

u-boot supports booting off a SPI flash chip if the SoC supports it
and it's wired up to the right interface, basically the Primary Boot
Loader (the actual on SoC firmware - PBL) has a boot order which in
tern loads the Secondary Boot Loader which inits RAM, loads u-boot
which in tern boots Linux. If the PBL supports loading SPL from SPI it
will retrieve that, and then SBL can retrieve u-boot from the SPI, and
it can then search for Fedora on MMC, USB or netboot etc.

In the vast majority of cases Fedora/Linux doesn't even have to be
aware of the existence of the SPI flash because it doesn't care where
the firmware is located, it only actually matters if you need to write
out a new version of u-boot firmwares to the SPI flash in which case
you'll generally do it with something like flashrom [1].

Peter

[1] https://www.flashrom.org/