fix: generate libv4l t64 compatibility package

AGENTS.md

@@ -2794,6 +2794,16 @@ no replacement userspace build is needed.
   `collect_declared_bsp_pkgs` and the pin file's names); `fetch_bsp` EXCLUDES exactly
   this set from the Armbian fetch. An x86 family declares none. DRY_RUN logs the exact
   URLs + hashes and downloads nothing.
+- **Trixie `libv4l-0` compatibility is a generated package, not a patched upstream
+  asset.** `libv4l-0t64` provides the old name to apt but dpkg records only the t64
+  name, while the pinned `rockchip-multimedia-config` postinst runs
+  `dpkg -L libv4l-0 | grep libv4l2.so.0.0.0` and then plain `cp`. A fileless package
+  cannot satisfy that grep. `fetch_rk3588_userspace` therefore builds a real arm64
+  `libv4l-0` depending on `libv4l-0t64`, with exactly one payload: a collision-free
+  `/usr/share/libv4l-0-compat/libv4l2.so.0.0.0` symlink to the t64-owned library.
+  The platform layer explicitly installs it first in the SAME `mkosi-install`
+  transaction as the Rockchip package. Never move the payload onto either
+  `/usr/lib/aarch64-linux-gnu/libv4l2.so.0*` path; both belong to `libv4l-0t64`.
 - **DO NOT** convert any of these into a `deb [signed-by=...] https://...` apt line —
   that is a new live trust root, exactly what the pinned-URL + SHA-256 approach avoids.
   **DO NOT** bump a pinned VERSION without re-proving HW encode (the versions are

docs/trixie-package-resolution.md

@@ -32,10 +32,32 @@ is still required before release — see "What this does not prove" at the end.
 
 ## Result
 
-**68 names checked. 66 unchanged. 2 diverged.** No `t64` rename touched any name
-in these lists — the transition renamed transitive dependencies only
-(`libext2fs2t64`, `libcurl4t64`, `libglib2.0-0t64`, `libssl3t64` all appear in the
-solved set, but none is named by us).
+**68 names checked. 66 unchanged. 2 diverged.** At the time of that audit no `t64`
+rename touched a name in the lists. A later real image build exposed one additional
+compatibility boundary in the pinned third-party Rockchip package, described below.
+
+### `libv4l-0` → `libv4l-0t64`: apt compatibility is not dpkg compatibility
+
+Trixie installs the real library from `libv4l-0t64` at
+`/usr/lib/aarch64-linux-gnu/libv4l2.so.0.0.0`. The package declares
+`Provides: libv4l-0`, so apt can satisfy `rockchip-multimedia-config`'s old-name
+dependency. Its postinst does not stop at dependency resolution, however:
+
+```sh
+libv4l_filename=$(dpkg -L libv4l-0 | grep libv4l2.so.0.0.0)
+cp ${libv4l_filename} /usr/lib64/libv4l2.so
+```
+
+`dpkg` records the installed provider as `libv4l-0t64`, so the exact-name listing
+fails. A fileless transitional package also fails because the grep needs a payload
+path. The pipeline therefore builds an arm64 package named `libv4l-0` at fetch time.
+It depends on `libv4l-0t64` and contains one file: the collision-free symlink
+`/usr/share/libv4l-0-compat/libv4l2.so.0.0.0` pointing at the real t64 library.
+Plain `cp` dereferences that link. The package is explicitly named first in the same
+platform-layer `mkosi-install` transaction as `rockchip-multimedia-config`; it owns
+neither `/usr/lib/aarch64-linux-gnu/libv4l2.so.0.0.0` nor the adjacent soname link.
+This preserves the SHA-256-pinned third-party `.deb` unchanged while giving its
+legacy maintainer script a real dpkg package record and readable path.
 
 ### The two divergences
 

lib/fetch/userspace.sh

@@ -15,6 +15,71 @@
 # Bodies moved VERBATIM from fetch-debs.sh; no behaviour change.
 #
 # shellcheck shell=bash
+
+LIBV4L0_COMPAT_VERSION="1.30.1-1+ceralive1"
+LIBV4L0_COMPAT_LINK="usr/share/libv4l-0-compat/libv4l2.so.0.0.0"
+LIBV4L0_T64_LIBRARY="/usr/lib/aarch64-linux-gnu/libv4l2.so.0.0.0"
+
+# build_libv4l0_compat_deb <debs-dir> — generate the real old-name package that
+# rockchip-multimedia-config's pre-t64 postinst asks dpkg to list. Trixie's
+# libv4l-0t64 Provides: libv4l-0 satisfies apt, but `dpkg -L libv4l-0` still has
+# no package record. A fileless transitional package also fails because the
+# postinst greps that listing for libv4l2.so.0.0.0 before copying it.
+#
+# The sole payload is therefore a collision-free symlink under /usr/share. Plain
+# `cp` in the pinned postinst dereferences it to libv4l-0t64's real library; this
+# package never owns either library path. The version sorts above 1.30.1-1 so it
+# is not caught by libv4l-0t64's `Breaks: libv4l-0 (<< 1.30.1-1)` relation.
+build_libv4l0_compat_deb() (
+  local debs="$1"
+  [[ "${ARCH}" == "arm64" ]] \
+    || die "libv4l-0 compatibility package is arm64-only (got ARCH=${ARCH})"
+  if ! command -v ar >/dev/null 2>&1 || ! command -v tar >/dev/null 2>&1; then
+    die "building libv4l-0 compatibility package requires ar and tar"
+  fi
+
+  local epoch="${SOURCE_DATE_EPOCH:-0}"
+  [[ "${epoch}" =~ ^[0-9]+$ ]] \
+    || die "SOURCE_DATE_EPOCH must be an integer (got '${epoch}')"
+  install -d -m 0755 "${debs}"
+
+  local work out tmp
+  work="$(mktemp -d "${debs}/.libv4l-0-compat.XXXXXX")"
+  trap 'rm -rf "${work}" "${tmp:-}"' EXIT
+  out="${debs}/libv4l-0_${LIBV4L0_COMPAT_VERSION}_arm64.deb"
+  tmp="${work}/libv4l-0.deb"
+
+  install -d -m 0755 "${work}/control" \
+    "${work}/data/$(dirname "${LIBV4L0_COMPAT_LINK}")"
+  cat >"${work}/control/control" <<EOF
+Package: libv4l-0
+Version: ${LIBV4L0_COMPAT_VERSION}
+Architecture: arm64
+Section: oldlibs
+Priority: optional
+Depends: libv4l-0t64
+Maintainer: CeraLive <engineering@ceralive.tv>
+Description: compatibility package for pre-t64 Rockchip multimedia configuration
+ This transitional package supplies the old dpkg package name and a collision-free
+ symlink to libv4l-0t64's libv4l2 library for legacy maintainer scripts.
+EOF
+  ln -s "${LIBV4L0_T64_LIBRARY}" "${work}/data/${LIBV4L0_COMPAT_LINK}"
+  printf '2.0\n' >"${work}/debian-binary"
+
+  tar --sort=name --mtime="@${epoch}" --owner=0 --group=0 --numeric-owner \
+    -C "${work}/control" -czf "${work}/control.tar.gz" ./control
+  tar --sort=name --mtime="@${epoch}" --owner=0 --group=0 --numeric-owner \
+    -C "${work}/data" -czf "${work}/data.tar.gz" .
+  ar rcD "${tmp}" "${work}/debian-binary" "${work}/control.tar.gz" "${work}/data.tar.gz"
+  chmod 0644 "${tmp}"
+
+  if ! assert_deb_identity "${tmp}" libv4l-0 "${LIBV4L0_COMPAT_VERSION}" arm64; then
+    die "generated libv4l-0 compatibility package has invalid Debian control identity"
+  fi
+  mv -f "${tmp}" "${out}"
+  log_success "RK3588 userspace: built libv4l-0 compatibility package -> ${out}"
+)
+
 # rk3588_userspace_pkg_names — echo every pinned userspace package NAME (col 1)
 # from the pin file. Empty (success) when the file is absent — a family that
 # declares no RK3588 userspace package simply matches none of these.
@@ -128,6 +193,18 @@ fetch_rk3588_userspace() {
   _run_bounded "${jobs}" _fetch_rk3588_userspace_one "${want[@]}" \
     || die "RK3588 userspace fetch failed: one or more pinned packages did not download/verify"
 
+  local needs_libv4l0_compat=0
+  for name in "${want[@]}"; do
+    [[ "${name}" == "rockchip-multimedia-config" ]] && needs_libv4l0_compat=1
+  done
+  if (( needs_libv4l0_compat )); then
+    if [[ -n "${DRY_RUN}" ]]; then
+      log_info "DRY-RUN would build: libv4l-0_${LIBV4L0_COMPAT_VERSION}_arm64.deb (Depends: libv4l-0t64; one compatibility symlink)"
+    else
+      build_libv4l0_compat_deb "${debs}"
+    fi
+  fi
+
   if [[ -z "${DRY_RUN}" ]]; then
     local pkg
     local -a staged=()

lib/stages/partition.sh

@@ -64,7 +64,7 @@ assert_staged_packages_unique() {
 stage_partition() {
   log_info "[3/9] partitioning staged .debs into BSP vs first-party by package name"
   # The set of BSP package names (manifest-declared) is the partition key.
-  local bsp_names=" ${KERNEL_PACKAGES} ${DTB_PACKAGES} ${UBOOT_PACKAGES} ${FIRMWARE_PACKAGES} ${HW_ACCEL_GSTREAMER_PLUGINS:-} ${GSTREAMER_RUNTIME_PACKAGES:-} "
+  local bsp_names=" libv4l-0 ${KERNEL_PACKAGES} ${DTB_PACKAGES} ${UBOOT_PACKAGES} ${FIRMWARE_PACKAGES} ${HW_ACCEL_GSTREAMER_PLUGINS:-} ${GSTREAMER_RUNTIME_PACKAGES:-} "
   # MUST stay a superset of fetch-debs.sh FIRST_PARTY_APT_PKGS: the 5 core packages
   # + the 9-package ModemManager 1.24 closure and its Architecture: all support
   # companion (modem-stack v1.3.0). The fetcher stages all 15 into debs/; a name missing here fails the build as

mkosi/mkosi.images/platform/mkosi.postinst

@@ -379,6 +379,12 @@ prune_irrelevant_rk3588_firmware() {
 # Collect the always-on HW-accel GStreamer set (parity-relevant) from env.
 read -r -a hw_gst <<<"${HW_ACCEL_GSTREAMER_PLUGINS:-}"
 read -r -a gst_runtime <<<"${GSTREAMER_RUNTIME_PACKAGES:-}"
+compat_pkgs=()
+for pkg in "${gst_runtime[@]}"; do
+  if [[ "${pkg}" == "rockchip-multimedia-config" ]]; then
+    compat_pkgs+=(libv4l-0)
+  fi
+done
 
 # Boot BSP (kernel/DTB/U-Boot/firmware) — only when explicitly requested.
 boot_bsp=()
@@ -390,7 +396,7 @@ if [[ "${INSTALL_BOOT_BSP}" == "1" ]]; then
   boot_bsp+=("${_k[@]}" "${_d[@]}" "${_u[@]}" "${_f[@]}")
 fi
 
-bsp_pkgs=("${hw_gst[@]}" "${gst_runtime[@]}" "${boot_bsp[@]}")
+bsp_pkgs=("${compat_pkgs[@]}" "${hw_gst[@]}" "${gst_runtime[@]}" "${boot_bsp[@]}")
 if [[ ${#bsp_pkgs[@]} -eq 0 ]]; then
   log "no BSP packages resolved from manifest — nothing to install."
   exit 0
@@ -416,9 +422,9 @@ install_chroot_service_policy() {
 }
 install_chroot_service_policy
 
-log "installing authenticated staged HW-accel GStreamer BSP: ${hw_gst[*]} ${gst_runtime[*]}"
+log "installing authenticated staged HW-accel GStreamer BSP: ${compat_pkgs[*]} ${hw_gst[*]} ${gst_runtime[*]}"
 if [[ ${#hw_gst[@]} -gt 0 || ${#gst_runtime[@]} -gt 0 ]]; then
-  mkosi-install -y --no-install-recommends "${hw_gst[@]}" "${gst_runtime[@]}"
+  mkosi-install -y --no-install-recommends "${compat_pkgs[@]}" "${hw_gst[@]}" "${gst_runtime[@]}"
 fi
 
 if [[ "${INSTALL_BOOT_BSP}" == "1" && ${#boot_bsp[@]} -gt 0 ]]; then

tests/mkosi-image-contract.bats

@@ -557,7 +557,7 @@ PY
   [ -n "$policy_at" ] && [ -n "$apt_at" ] && [ "$policy_at" -lt "$apt_at" ]
 
   policy_at="$(grep -n '^install_chroot_service_policy$' "$PIPELINE_DIR/mkosi/mkosi.images/platform/mkosi.postinst" | cut -d: -f1)"
-  apt_at="$(grep -n '^  mkosi-install -y --no-install-recommends "\${hw_gst\[@\]}"' "$PIPELINE_DIR/mkosi/mkosi.images/platform/mkosi.postinst" | cut -d: -f1)"
+  apt_at="$(grep -n '^  mkosi-install -y --no-install-recommends "\${compat_pkgs\[@\]}" "\${hw_gst\[@\]}"' "$PIPELINE_DIR/mkosi/mkosi.images/platform/mkosi.postinst" | cut -d: -f1)"
   [ -n "$policy_at" ] && [ -n "$apt_at" ] && [ "$policy_at" -lt "$apt_at" ]
 }
 

tests/package-contract.bats

@@ -542,6 +542,47 @@ PY
   [ "$(sed -n 's/^v4l-utils[[:space:]]*//p' "$shared" | head -n 1 >/dev/null; grep -n '^v4l-utils[[:space:]]' "$shared" | cut -d: -f1)" -lt "$(grep -n '^libv4l-0[[:space:]]' "$shared" | cut -d: -f1)" ]
 }
 
+@test "RK3588 multimedia config: generated libv4l-0 compat package carries exactly the t64 library symlink" {
+  local debs="$BATS_TEST_TMPDIR/libv4l-compat-debs"
+  local root="$BATS_TEST_TMPDIR/libv4l-compat-root"
+  mkdir -p "$debs" "$root"
+
+  run env ARCH=arm64 SOURCE_DATE_EPOCH=1 bash -c \
+    'source "$1"; build_libv4l0_compat_deb "$2"' bash "$FETCH_DEBS" "$debs"
+  [ "$status" -eq 0 ]
+
+  local deb="$debs/libv4l-0_1.30.1-1+ceralive1_arm64.deb"
+  [ -f "$deb" ]
+  [ "$(bash -c 'source "$1"; deb_pkg_name "$2"' bash "$FETCH_DEBS" "$deb")" = "libv4l-0" ]
+  [ "$(bash -c 'source "$1"; deb_pkg_version "$2"' bash "$FETCH_DEBS" "$deb")" = "1.30.1-1+ceralive1" ]
+  [ "$(bash -c 'source "$1"; deb_pkg_arch "$2"' bash "$FETCH_DEBS" "$deb")" = "arm64" ]
+  [ "$(bash -c 'source "$1"; deb_control_field "$2" Depends' bash "$FETCH_DEBS" "$deb")" = "libv4l-0t64" ]
+
+  bash -c 'source "$1"; explode_deb "$2" "$3"' bash "$FETCH_DEBS" "$deb" "$root"
+  [ "$(find "$root" -type f | wc -l)" -eq 0 ]
+  [ "$(find "$root" -type l | wc -l)" -eq 1 ]
+  local link="$root/usr/share/libv4l-0-compat/libv4l2.so.0.0.0"
+  [ -L "$link" ]
+  [ "$(readlink "$link")" = "/usr/lib/aarch64-linux-gnu/libv4l2.so.0.0.0" ]
+
+  grep -Fq 'work="$(mktemp -d "${debs}/.libv4l-0-compat.XXXXXX")"' \
+    "$REPO_ROOT/lib/fetch/userspace.sh"
+  grep -Fq 'tmp="${work}/libv4l-0.deb"' \
+    "$REPO_ROOT/lib/fetch/userspace.sh"
+  run ! grep -Fq 'tmp="${out}.tmp"' "$REPO_ROOT/lib/fetch/userspace.sh"
+}
+
+@test "RK3588 multimedia config: libv4l-0 compat is staged and named first in the platform transaction" {
+  local userspace="$REPO_ROOT/lib/fetch/userspace.sh"
+  local partition="$REPO_ROOT/lib/stages/partition.sh"
+  local platform="$REPO_ROOT/mkosi/mkosi.images/platform/mkosi.postinst"
+
+  grep -Fq 'build_libv4l0_compat_deb "${debs}"' "$userspace"
+  grep -Eq 'bsp_names=.*libv4l-0' "$partition"
+  grep -Fq 'compat_pkgs+=(libv4l-0)' "$platform"
+  grep -Fq 'mkosi-install -y --no-install-recommends "${compat_pkgs[@]}" "${hw_gst[@]}" "${gst_runtime[@]}"' "$platform"
+}
+
 @test "wwan: the check asserts a .deb extractor (dpkg-deb or ar+tar) is available" {
   # with a normal PATH the assertion passes (ar + tar are on the host)
   run bash -c "source '$CHECK_WWAN'; wwan_assert_deb_tools"