vcontainer: add sanity checks and auto-enable virtfs for QEMU

Add sanity check that warns when vcontainer distro feature is enabled
but BBMULTICONFIG is missing the required vruntime-* multiconfigs.

Add qemu-system-native bbappend to auto-enable virtfs (virtio-9p) when
vcontainer or virtualization distro feature is set. This is required
for the fast batch-import path in container-cross-install.

Signed-off-by: Bruce Ashfield <bruce.ashfield@gmail.com>

2 files changed, 46 insertions, 0 deletions

diff --git a/classes/sanity-meta-virt.bbclass b/classes/sanity-meta-virt.bbclass
index b4ed0825..3327a8ac 100644
--- a/classes/sanity-meta-virt.bbclass
+++ b/classes/sanity-meta-virt.bbclass
@@ -8,3 +8,39 @@ python virt_bbappend_distrocheck() {
 may not take effect. See the meta-virtualization README for details on enabling \
 virtualization support.")
 }
+
+# Check for vcontainer requirements when vcontainer distro feature is enabled
+addhandler vcontainer_sanity_check
+vcontainer_sanity_check[eventmask] = "bb.event.SanityCheck"
+python vcontainer_sanity_check() {
+    skip_check = e.data.getVar('SKIP_META_VIRT_SANITY_CHECK') == "1"
+    if skip_check:
+        return
+
+    distro_features = (e.data.getVar('DISTRO_FEATURES') or "").split()
+
+    if 'vcontainer' not in distro_features:
+        return
+
+    # Check for required BBMULTICONFIG
+    bbmulticonfig = e.data.getVar('BBMULTICONFIG') or ""
+    required_mcs = ['vruntime-aarch64', 'vruntime-x86-64']
+    missing_mcs = [mc for mc in required_mcs if mc not in bbmulticonfig]
+
+    if missing_mcs:
+        bb.warn("vcontainer: BBMULTICONFIG is missing required multiconfigs: %s\n"
+                "Add to local.conf:\n"
+                "  BBMULTICONFIG = \"vruntime-aarch64 vruntime-x86-64\"\n"
+                "This is required for building vdkr/vpdmn cross-architecture container tools."
+                % ', '.join(missing_mcs))
+
+    # Informational message about vcontainer setup
+    bb.note("vcontainer enabled. Required settings:\n"
+            "  DISTRO_FEATURES: vcontainer (detected)\n"
+            "  BBMULTICONFIG: vruntime-aarch64 vruntime-x86-64 %s\n"
+            "Optional settings:\n"
+            "  CONTAINER_PROFILE: docker|podman (default: docker)\n"
+            "  CONTAINER_REGISTRY_URL: registry address for container-registry feature\n"
+            "  BUNDLED_CONTAINERS: containers to bundle into images"
+            % ("(OK)" if not missing_mcs else "(MISSING)"))
+}
diff --git a/recipes-devtools/qemu/qemu-system-native_%.bbappend b/recipes-devtools/qemu/qemu-system-native_%.bbappend
new file mode 100644
index 00000000..d360af80
--- /dev/null
+++ b/recipes-devtools/qemu/qemu-system-native_%.bbappend
@@ -0,0 +1,10 @@
+# SPDX-FileCopyrightText: Copyright (C) 2025 Bruce Ashfield
+#
+# SPDX-License-Identifier: MIT
+#
+# Enable virtfs (virtio-9p) for vcontainer cross-architecture container bundling.
+# This is required for the fast batch-import path in container-cross-install.
+#
+# Only applied when "vcontainer" or "virtualization" is in DISTRO_FEATURES.
+
+PACKAGECONFIG:append = " ${@bb.utils.contains_any('DISTRO_FEATURES', 'vcontainer virtualization', 'virtfs', '', d)}"