Build Fedora aarch64 images for the Lenovo Yoga C630

Assembles a ready-to-write disk image via Gitea Actions. Mainline has carried
sdm850-lenovo-yoga-c630.dts since 5.5 and Fedora ships it in kernel-core, so
unlike aarch64-laptops/build there is no kernel or GRUB to compile — what is
left is producing an image that boots on firmware which hands Linux no device
tree.

The build runs in an aarch64 container under qemu-user and builds filesystems
from directory trees with mke2fs -d and mcopy rather than mounting loop
devices, so it works on runners that will not hand out /dev/loop-control.

A kernel-install hook writes the devicetree line into each BLS entry; without
it the first `dnf update kernel` would produce an unbootable system.

Co-Authored-By: Claude Opus 5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01XWRjNJMistCy6ngXH5aJLS

overlay/etc/default/grub.in

@@ -0,0 +1,13 @@
+GRUB_TIMEOUT=5
+GRUB_DISTRIBUTOR="$(sed 's, release .*$,,g' /etc/system-release)"
+GRUB_DEFAULT=saved
+GRUB_DISABLE_SUBMENU=true
+GRUB_TERMINAL_OUTPUT="console"
+GRUB_CMDLINE_LINUX="@DEVICE_CMDLINE@"
+GRUB_DISABLE_RECOVERY=true
+GRUB_ENABLE_BLSCFG=true
+
+# Consumed by grub2-mkconfig on aarch64. The BLS entries carry their own
+# `devicetree` line as well (written by 95-c630-devicetree.install), because
+# kernel-install does not read this file.
+GRUB_DEFAULT_DTB=/dtb/@DEVICE_DTB@

overlay/etc/dracut.conf.d/10-c630.conf

@@ -0,0 +1,12 @@
+# The image is built on a machine that is nothing like a C630, so the initramfs
+# must be generic — a host-only initramfs would contain the builder's drivers.
+hostonly="no"
+hostonly_cmdline="no"
+
+# UFS is the C630's only internal storage and the rootfs lives on it, so the
+# controller and PHY drivers have to be in the initramfs, not modules loaded
+# later from a filesystem we cannot yet read.
+add_drivers+=" ufshcd-core ufshcd-pltfrm ufs-qcom phy-qcom-qmp-ufs "
+
+# Needed before the display comes up, and cheap to include.
+add_drivers+=" nvmem_qfprom qcom_scm rtc-pm8xxx "

overlay/etc/kernel/install.d/95-c630-devicetree.install.in

@@ -0,0 +1,47 @@
+#!/usr/bin/bash
+#
+# Teach kernel-install about the C630's device tree.
+#
+# The C630's UEFI hands Linux no device tree, so GRUB has to load one. Fedora's
+# BLS snippets have a `devicetree` key for exactly this, but nothing in the
+# stock toolchain populates it — which means a plain `dnf update kernel` would
+# otherwise produce an unbootable entry. This hook runs after 20-grub.install
+# and patches the entry it just wrote.
+
+set -eu
+
+COMMAND="${1:?}"
+KERNEL_VERSION="${2:?}"
+
+DTB_REL="@DEVICE_DTB@"
+BOOT_ROOT="${KERNEL_INSTALL_BOOT_ROOT:-/boot}"
+ENTRIES_DIR="${BOOT_ROOT}/loader/entries"
+
+case "$COMMAND" in
+add)
+    dtb_path="/dtb-${KERNEL_VERSION}/${DTB_REL}"
+    if [ ! -e "${BOOT_ROOT}${dtb_path}" ]; then
+        echo "95-c630-devicetree: ${BOOT_ROOT}${dtb_path} is missing;" \
+             "leaving boot entries alone rather than writing a bad one" >&2
+        exit 0
+    fi
+
+    shopt -s nullglob
+    for entry in "${ENTRIES_DIR}"/*-"${KERNEL_VERSION}".conf; do
+        # Drop any stale devicetree line, then append the current one. Doing it
+        # in that order makes the hook idempotent across re-installs.
+        tmp="${entry}.c630.$$"
+        grep -v '^devicetree[[:space:]]' "$entry" > "$tmp"
+        printf 'devicetree %s\n' "$dtb_path" >> "$tmp"
+        mv -f "$tmp" "$entry"
+        echo "95-c630-devicetree: set devicetree ${dtb_path} in ${entry}"
+    done
+    ;;
+remove)
+    # The build writes its own bootstrap entry under a fixed name, which
+    # kernel-install would not otherwise clean up when the kernel goes away.
+    rm -f "${ENTRIES_DIR}/c630-${KERNEL_VERSION}.conf"
+    ;;
+esac
+
+exit 0

overlay/etc/motd.d/c630.in

@@ -0,0 +1,7 @@
+
+  Fedora @FEDORA_RELEASE@ for the @DEVICE_DESC@  (built @BUILD_DATE@ from @BUILD_REF@)
+
+  Graphics and WiFi work with the firmware Fedora ships. Audio, the sensor
+  hub and hardware video decode need per-model blobs from the Windows
+  partition — run `sudo c630-firmware` once to extract them.
+

overlay/etc/systemd/system/c630-growfs.service

@@ -0,0 +1,15 @@
+[Unit]
+Description=Grow C630 root filesystem to fill the medium
+DefaultDependencies=no
+After=systemd-remount-fs.service
+Before=local-fs.target sysinit.target
+ConditionPathExists=!/var/lib/c630/growfs-done
+
+[Service]
+Type=oneshot
+ExecStart=/usr/local/sbin/c630-growfs
+RemainAfterExit=yes
+StandardOutput=journal+console
+
+[Install]
+WantedBy=sysinit.target

overlay/usr/local/sbin/c630-firmware

@@ -0,0 +1,49 @@
+#!/usr/bin/bash
+#
+# Pull the model-specific Qualcomm blobs off this machine's Windows partition.
+#
+# Fedora ships everything for the C630 that Qualcomm allows to be redistributed
+# — Adreno 630 (graphics) and ath10k WCN3990 (WiFi/Bluetooth) both work out of
+# the box. What it cannot ship is the per-model signed firmware: the ADSP, the
+# compute DSP, and the display/UEFI blob. Those are signed against this
+# machine's own keys and live only in its Windows install.
+#
+# Without them you lose audio, the sensor hub (lid switch, accelerometer,
+# auto-rotate) and hardware video decode. Everything else still works.
+
+set -euo pipefail
+
+if [ "$(id -u)" -ne 0 ]; then
+    echo "c630-firmware: needs root — try: sudo c630-firmware" >&2
+    exit 1
+fi
+
+echo "Looking for a Windows installation to extract firmware from..."
+echo
+
+if ! command -v qcom-firmware-extract >/dev/null; then
+    echo "qcom-firmware-extract is not installed. Install it with:" >&2
+    echo "    sudo dnf install qcom-firmware-extract" >&2
+    exit 1
+fi
+
+qcom-firmware-extract "$@"
+
+echo
+echo "Regenerating the initramfs so the DSP firmware is available early..."
+dracut --force --regenerate-all
+
+cat <<'EOF'
+
+Done. Reboot to pick up the new firmware.
+
+If qcom-firmware-extract could not find the Windows partition, mount it by hand
+and point the tool at it:
+
+    sudo mkdir -p /mnt/windows
+    sudo mount /dev/disk/by-partlabel/Windows /mnt/windows   # adjust as needed
+    sudo qcom-firmware-extract --windows-dir /mnt/windows
+
+See docs/firmware.md in the c630 repo for the full file list and the manual
+fallback if the tool does not recognise this model.
+EOF

overlay/usr/local/sbin/c630-growfs

@@ -0,0 +1,43 @@
+#!/usr/bin/bash
+#
+# Grow the root partition and filesystem to fill the medium.
+#
+# The image is built at a fixed size so the artifact stays small; whatever it
+# gets written to is almost always bigger. Runs once, then disables itself.
+
+set -euo pipefail
+
+STAMP=/var/lib/c630/growfs-done
+
+root_src="$(findmnt -no SOURCE /)"
+root_dev="$(basename "$root_src")"
+
+part_num_file="/sys/class/block/${root_dev}/partition"
+if [ ! -r "$part_num_file" ]; then
+    echo "c630-growfs: / is on ${root_src}, which is not a partition — nothing to grow"
+    mkdir -p "$(dirname "$STAMP")" && touch "$STAMP"
+    exit 0
+fi
+
+part_num="$(cat "$part_num_file")"
+disk="/dev/$(lsblk -no pkname "$root_src")"
+
+# The image was written with dd, so the secondary GPT header is still sitting
+# where the end of the image used to be. growpart refuses to touch a disk in
+# that state, so move it to the real end of the device first.
+sgdisk --move-second-header "$disk" || true
+
+if growpart "$disk" "$part_num"; then
+    echo "c630-growfs: grew ${disk}${part_num}"
+else
+    # growpart exits non-zero with NOCHANGE when the partition already fills
+    # the disk. That is a success for our purposes.
+    echo "c630-growfs: partition already at full size"
+fi
+
+partprobe "$disk" || true
+resize2fs "$root_src"
+
+mkdir -p "$(dirname "$STAMP")"
+touch "$STAMP"
+echo "c630-growfs: done"