[U-Boot] [PATCH v7 7/9] riscv: sifive: fu540: Setup ethaddr env variable using OTP

[Joe Hershberger]

On Mon, Jul 22, 2019 at 12:46 PM Joey Hewitt <joey.hewitt at gmail.com> wrote:
>
> On 7/10/19 10:28 PM, Anup Patel wrote:

[ ... ]

> >> Please take a look at the DM-enabled SiFive OTP driver submitted by Joey
> >> Hewitt at https://github.com/sifive/HiFive_U-
> >> Boot/commit/6d842765de142b61f847852da7a9ce0d081d770c
> >>
> >> This Joey's version also sets the ‘serial#’ environment variable, while this
> >> patch only sets ‘ethaddr'
> >
> > I am not sure if "serial#" environment variable is a standard U-Boot
> > way of advertising serial number of underlying Host.
> >
> > Where is this used?
> >
> > Regards,
> > Anup
> >
>
> The serial# var is inserted into the device tree.
> https://github.com/u-boot/u-boot/blob/0de815356474912ef5bef9a69f0327a5a93bb2c2/common/fdt_support.c#L199
>
> See also
> https://github.com/torvalds/linux/commit/13dd92bb4599b5655cafe1f2c0365396a096b94a
>
> I don't recall if it had any particularly special meaning on the kernels
> I tested with, but it seems to be standard and could be useful to userspace.

You can find the so-called "built in" variables here:
https://gitlab.denx.de/u-boot/u-boot/blob/master/include/env_flags.h

It is fairly common for a board.c to set the serial# variable.

-Joe