# Firmware

The C630's firmware splits into two groups, and the split is about licensing,
not difficulty.

## What ships in the image

Qualcomm permits redistribution of these, so Fedora packages them and the build
installs them:

| Package | Files | Enables |
|---|---|---|
| `atheros-firmware` | `ath10k/WCN3990/hw1.0/{firmware-5.bin,board-2.bin,wlanmdsp.mbn}` | WiFi and Bluetooth |
| `qcom-firmware` | `qcom/a630_gmu.bin`, `qcom/a630_sqe.fw` | The generic half of the Adreno 630 — necessary but not sufficient |

Networking therefore works on a freshly written image. Graphics does not: see
below.

## What has to come off the Windows partition

These are signed against per-model keys, so nobody can redistribute them and
they exist on your machine only inside its Windows install. The list is not a
guess — it is every `firmware-name` property in the mainline device tree,
`arch/arm64/boot/dts/qcom/sdm850-lenovo-yoga-c630.dts`:

| File | Device tree node | Lost without it |
|---|---|---|
| `qcdxkmsuc850.mbn` | `gpu_zap_shader` | **Accelerated graphics** |
| `qcadsp850.mbn` | `adsp_pas` | Audio — speakers, microphone |
| `qcslpi850.mbn` | `slpi_pas` | Sensor hub — lid switch, accelerometer, auto-rotate |
| `qccdsp850.mbn` | `cdsp_pas` | Compute DSP offload |
| `qcvss850.mbn` | `venus` | Hardware video decode |
| `qcdsp1v2850.mbn` | `mss_pil` | Modem, stage 1 |
| `qcdsp2850.mbn` | `mss_pil` | Modem, stage 2 |
| `ipa_fws.elf` | `ipa` | IPA datapath, needed by the modem |

They belong under `/lib/firmware/updates/qcom/sdm850/LENOVO/81JL/`.

The GPU one is worth calling out, because it is easy to assume otherwise:
Fedora does ship an `sdm845/a630_zap.mbn`, but that is the generic
Snapdragon 845 zap shader and **not** what this device asks for. The C630's
device tree names `qcom/sdm850/LENOVO/81JL/qcdxkmsuc850.mbn` specifically, so
until you supply it you get an unaccelerated display.

Each file is independent, so a partial recovery is still worth having —
`qcdxkmsuc850.mbn` on its own buys you working graphics.

### Confirmed on the hardware

This is not inferred from the device tree. On a machine with the generic
Adreno firmware present and the model-signed blob absent, the GPU gets two
files in and then stops:

```
[drm:adreno_request_fw]   loaded qcom/a630_sqe.fw from new location
[drm:adreno_request_fw]   loaded qcom/a630_gmu.bin from new location
[drm:zap_shader_load_mdt] *ERROR* Unable to load qcom/sdm850/LENOVO/81JL/qcdxkmsuc850.mbn
[drm:adreno_load_gpu]     *ERROR* gpu hw init failed: -2
```

So the generic pieces are necessary and not sufficient, and the zap shader is a
hard requirement rather than an optimisation. Two details follow from that
trace:

The driver never falls back to `sdm845/a630_zap.mbn`, even though the file is
installed — the device tree's `firmware-name` pins the model-specific path. Nor
would falling back help: the zap shader is signed against the device's own
secure-boot chain, and the Snapdragon 845 development board's copy will not
validate here.

The display keeps working throughout. `msm_dpu` binds the panel and the console
lands on `msmdrmfb` regardless, so a failed GPU costs you acceleration, not a
picture. A desktop still runs on llvmpipe — though `/dev/dri/renderD128` is
present even when `hw init` has failed, so mesa may try freedreno, fail, and
take the display manager down with it. `LIBGL_ALWAYS_SOFTWARE=1` in
`/etc/environment` avoids that.

### These have to be in the initramfs

`msm_dpu` probes about six seconds in, while the initramfs is still the root
filesystem, and does not retry. Firmware that only exists on the real root is
therefore invisible to it:

```
msm_dpu ae01000.display-controller: Direct firmware load for qcom/a630_sqe.fw failed with error -2
```

`overlay/etc/dracut.conf.d/10-c630.conf` puts the Adreno files in the initramfs
for this reason, and `c630-firmware` adds the extracted DSP blobs to it after
extraction — the ADSP has to be up before the root filesystem is mounted, and
dracut rejects `install_items` globs that match nothing, so the entry can only
be written once the files exist.

## Finding them on a backup

If Windows is long gone from the machine but you kept a copy of the files, one
search catches all eight, since seven share a suffix:

```sh
find /mnt/backup -type f \
    \( -iname 'qc*850.mbn' -o -iname 'ipa_fws.elf' -o -iname 'bdwlan*.bin' \) \
    -printf '%10s  %p\n'
```

They originally lived in `C:\Windows\System32\DriverStore\FileRepository\`, in
directories named `qcdx850.inf_arm64_*` and `qcadsp*.inf_arm64_*`. If the loose
files turn up nothing, look for those directories wholesale:

```sh
find /mnt/backup -type d -iname 'qc*.inf_arm64_*'
```

Expect a few hundred KB to a few MB each. `file` reports them as `data` — they
are signed Qualcomm MBN containers, not ELF, apart from `ipa_fws.elf`.

Lenovo does not appear to publish a driver package for the 81JL containing
these, so an old backup or a surviving Windows partition are the only routes.

## Extracting them

The image ships Fedora's `qcom-firmware-extract`. Run it once:

```sh
sudo c630-firmware
sudo reboot
```

That wraps `qcom-firmware-extract` and regenerates the initramfs afterwards,
which matters — the ADSP firmware has to be available before the root
filesystem is mounted, and `overlay/etc/dracut.conf.d/10-c630.conf` only takes
effect on a rebuild.

If it cannot find Windows, mount it yourself and point the tool at it:

```sh
lsblk -o NAME,SIZE,FSTYPE,LABEL       # find the NTFS partition
sudo mkdir -p /mnt/windows
sudo mount /dev/sda4 /mnt/windows
sudo qcom-firmware-extract --windows-dir /mnt/windows
```

`qcom-firmware-extract` was written for the Snapdragon 8cx and X Elite laptops.
If it does not recognise the SDM850, copy the files by hand — they are in
`Windows/System32/DriverStore/FileRepository/` under a `qcdx*.inf_arm64_*`
directory:

```sh
sudo find /mnt/windows/Windows/System32/DriverStore/FileRepository \
    -iname 'qc*850.mbn' -o -iname 'ipa_fws.elf' -o -iname 'qcdxkmsuc850.mbn'

sudo mkdir -p /lib/firmware/updates/qcom/sdm850/LENOVO/81JL
sudo cp <each file> /lib/firmware/updates/qcom/sdm850/LENOVO/81JL/
sudo dracut --force --regenerate-all
```

Check it took:

```sh
dmesg | grep -iE 'remoteproc|adsp|cdsp'
```

## Baking firmware into the image

If you would rather not repeat the extraction on every reinstall, drop the files
into `firmware/local/` in this repo, mirroring the `/usr/lib/firmware/updates/`
layout:

```
firmware/local/qcom/sdm850/LENOVO/81JL/qcadsp850.mbn
firmware/local/qcom/sdm850/LENOVO/81JL/qccdsp850.mbn
...
```

`build/stage2.sh` picks them up automatically. They are gitignored, and should
stay that way — this repository is public and the blobs are not yours to
publish.