fp6-img/README.md

# fp6-img

Flashable [postmarketOS](https://postmarketos.org/) images for the
**Fairphone 6**, built nightly from the
[Catcrafts milos-linux](https://forgejo.catcrafts.net/Catcrafts/milos-linux)
`combined-stable` kernel branch, with
[imsd](https://forgejo.catcrafts.net/Catcrafts/imsd) (userspace VoLTE)
preinstalled.

Maintained by [Jorijn van der Graaf](https://catcrafts.net/about)
(TheMightyCat) at [Catcrafts](https://catcrafts.net/).

> [!CAUTION]
> **Emergency calling is unverified.** Calls (including 112/911) go through
> imsd, whose emergency path is spec-shaped but has never been verified
> against a live network.

## What works

Everything on the `combined-stable` branch: display, touch, wifi, cellular
data, NFC (reader), speaker audio, microphone, IMU, magnetometer, barometer,
ambient light/proximity — plus VoLTE calls (both directions) through imsd.

Verified on exactly one device / one carrier (KPN NL). Reports from other
carriers are very welcome.

## Known issues

- **Fixed in builds ≥ `7.1.2_git20260814`**: intermittent GPU wedge under
  bursty use (e.g. browser scrolling) — `a6xx_gmu_resume: GMU firmware
  initialization timed out` followed by a hangcheck/recovery storm, sometimes
  taking the session down. The kernel skipped the GPU's RPMh sleep sequence
  on every GPU suspend (stale power votes broke a later GPU wake); fix
  carried from upstream ("drm/msm/a6xx: Fix stale rpmh votes after suspend",
  currently in drm-msm `msm-next`). Occasional
  `delay in fenced register write (0x8c1)` lines are unrelated and harmless.

## Flashing

Download `fp6-img.tar.xz` from the latest release and unlock the bootloader
([Fairphone's official process](https://support.fairphone.com/hc/en-us/articles/10492476238737)).

**Install**: with the phone in fastboot mode,

```sh
tar xf fp6-img.tar.xz
cd fp6-img
./install.sh
```

`install.sh` erases dtbo, flashes the rootfs, **RAM-boots** the kernel, writes the boot partition from
inside Linux where the bootloader's NV-wipe cannot see it, then reads the modem
NV back and reports the result. The bootloader never writes `boot`.

Default login: `user` / `147147` (same as official postmarketOS images —
change it). **Never re-lock the bootloader** with a custom image installed.

## VoLTE configuration

imsd is installed but needs your carrier's P-CSCF address:

```sh
# /etc/imsd.env
PCSCF=<your carrier's P-CSCF IPv6 address>
```

Find it in a stock-firmware capture or your carrier's IMS documentation, then
`systemctl restart imsd` (the service is enabled at boot and waits for this
file to exist). See the
[imsd README](https://forgejo.catcrafts.net/Catcrafts/imsd) for the full
variable reference and carrier assumptions.

## How it builds

`build.sh` drives [pmbootstrap](https://gitlab.postmarketos.org/postmarketOS/pmbootstrap)
with the `aports/` overlay in this repository:

- `device/linux-postmarketos-qcom-milos` — the pmaports kernel aport,
  repointed at `combined-stable` with the exact kernel config the development FP6 runs.
- `modem/imsd` — imsd, packaged from source. Its `provides=81voltd` keeps the
  conflicting modem-firmware IMS helper off the image (two IMS stacks cannot
  share one PDN).
- `main/postmarketos-config-nftables` — adds the `-imsd` subpackage accepting
  imsd's IPsec-protected SIP ports on the IMS PDN (auto-installed alongside
  imsd).