Subject: [bug#31308] [PATCH 0/3] Support u-boot on wandboard and mx6cuboxi

From: Vagrant Cascadian <[email-masked]>
Date: Tue, 01 May 2018 14:41:38 -0700

On 2018-05-01, Danny Milosavljevic <[email-masked]> wrote:
> For an eventual u-boot-installer, how do you install u-boot on wandboard?
>
> And how do we detect that we have to use this kind of installation method based on u-boot's .config ?

An interesting idea... I had thought about making an SD image either as
a separate target, or integrating it into u-boot-BOARD for targets that
support booting from SD.

> For comparison, for sunxi, it's:
>
> .config contains CONFIG_SYS_SOC="sunxi" => install via "dd if=u-boot-sunxi-with-spl.bin of=/dev/sdX bs=1024 seek=8".

I've been using:

  https://salsa.debian.org/debian/u-boot/blob/master/debian/u-boot-imx.README.Debian

Which pretty much comes down to:

  dd conv=fsync,notrunc if=SPL of=DEVICE|IMAGEFILE bs=1k seek=1
  dd conv=fsync,notrunc if=u-boot.img of=DEVICE|IMAGEFILE bs=1k seek=69

That works on wandboard and mx6cuboxi, as well as several other imx6
targets.

The novena target requires u-boot.img to be copied to the first
partition with a fat or ext filesystem, and only the SPL is written to
the raw device.

With usbarmory (imx5), only the u-boot.img portion is installed directly
to the raw device at the offset above; there is no SPL.

CONFIG_SPL=y seems to be the best indicator that it needs SPL, and as
far as I know with CONFIG_MX[5,6]=y SPL is always installed to the same
offset.

It's less obvious to me comparing other configuration options what
determines which method is needed for u-boot.img. Maybe with recent
u-boot versions, it's possible to use either an offset or read it from a
filesystem with a single image; I didn't have much luck with that in the
past.

I'll experiment a little more and see what I can figure out.

live well,
  vagrant