It's not very obvious that there devices that can attach on RPi4 only if
the UEFI firmware to set to FDT mode.
Also, the UEFI firmware for RPi4 defaults to capping physical memory to
3 GB since the DMA controller can't access memory above 3 GB and Linux
doesn't have a workaronud for that.
Going
Doug Moss writes:
> In the UEFI (1.16) configuration, I have changed
> from default "ACPI" to "ACPI + devicetree"
> from default "Arasan SDHCI" to "eMMC2 SDHCI"
> (Is this description
> https://mail-index.netbsd.org/port-arm/2017/07/30/msg004328.html
> accurate that the eMMC2 uses the sdho
