nerves_system_openwrt_one

# Prebuilt blobs for OpenWRT One NAND boot

## openwrt-one-fip.bin

ARM Trusted Firmware FIP (Firmware Image Package) containing BL31 and
the OpenWrt-built U-Boot proper for the OpenWRT One. Loaded by BL2
(in SPI NOR `bl2-nor` partition) from the `fip` UBI volume on SPI NAND.

This is a pre-built binary blob extracted from the official OpenWrt
release because it's signed/built with the MediaTek ATF fork which is
not in mainline TF-A and we deliberately don't build it ourselves.

**Source**: `openwrt-24.10.0-mediatek-filogic-openwrt_one-factory.ubi`,
volume name `fip`, downloaded from
<https://downloads.openwrt.org/releases/24.10.0/targets/mediatek/filogic/>

**To extract from a fresh factory.ubi**:

```sh
pip install --user ubi_reader
ubireader_extract_images -o /tmp/extract \
    openwrt-24.10.0-mediatek-filogic-openwrt_one-factory.ubi
cp /tmp/extract/*/img-*_vol-fip.ubifs openwrt-one-fip.bin
```

The first 4 bytes should be `01 00 64 aa` (ToC magic `0xaa640001` LE)
to confirm it's a valid FIP container.

**Why we ship this**: BL2 in `bl2-nor` looks for a UBI volume named
`fip` on SPI NAND to load BL33 (U-Boot proper). Without it, BL2 fails
and the board can only boot via the SPI NOR recovery path (front
button hold + NAND/NOR switch). Including the official fip in our
NAND image keeps the production autoboot path working.

## openwrt-one-snand-preloader.bin

OpenWrt's SPI NAND BL2 preloader (the same binary that ships in the
factory image as the `bl2` volume contents). It's built from the
MediaTek ATF fork (same reason we don't build the FIP ourselves).

`mix burn` packages this onto the recovery USB stick under the
filename **`openwrt-mediatek-filogic-openwrt_one-snand-preloader.bin`**
because OpenWrt's SPI NOR recovery U-Boot looks for that exact
filename when the user boots into "NOR full recovery mode" (boot
switch on NOR + front button held + power on). The recovery U-Boot
loads the preloader from FAT USB partition 1 and writes it to the
`bl2` partition (mtd4) on SPI NAND, then continues with the
`factory.ubi` for the rest.

**Source**:
<https://downloads.openwrt.org/releases/24.10.0/targets/mediatek/filogic/openwrt-24.10.0-mediatek-filogic-openwrt_one-snand-preloader.bin>