vcontainer: add kernel config fragments for container support

Add kernel configuration fragments required for vdkr/vpdmn:
- 9p.cfg: 9P filesystem for virtio-9p file sharing (volume mounts)
- squashfs.cfg: Squashfs and overlayfs for rootfs images

Only applied when "vcontainer" is in DISTRO_FEATURES.

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

3 files changed, 23 insertions, 0 deletions

diff --git a/recipes-kernel/linux/files/9p.cfg b/recipes-kernel/linux/files/9p.cfg
new file mode 100644
index 00000000..bd5a74f1
--- /dev/null
+++ b/recipes-kernel/linux/files/9p.cfg
@@ -0,0 +1,5 @@
+# 9P filesystem support for virtio-9p file sharing
+CONFIG_NET_9P=y
+CONFIG_NET_9P_VIRTIO=y
+CONFIG_9P_FS=y
+CONFIG_9P_FS_POSIX_ACL=y
diff --git a/recipes-kernel/linux/files/squashfs.cfg b/recipes-kernel/linux/files/squashfs.cfg
new file mode 100644
index 00000000..f67fadcd
--- /dev/null
+++ b/recipes-kernel/linux/files/squashfs.cfg
@@ -0,0 +1,5 @@
+# Squashfs and overlayfs support for vdkr/vpdmn rootfs images
+CONFIG_SQUASHFS=y
+CONFIG_SQUASHFS_XZ=y
+CONFIG_SQUASHFS_ZSTD=y
+CONFIG_OVERLAY_FS=y
diff --git a/recipes-kernel/linux/linux-yocto_%.bbappend b/recipes-kernel/linux/linux-yocto_%.bbappend
new file mode 100644
index 00000000..b6af23a7
--- /dev/null
+++ b/recipes-kernel/linux/linux-yocto_%.bbappend
@@ -0,0 +1,13 @@
+# SPDX-FileCopyrightText: Copyright (C) 2025 Bruce Ashfield
+#
+# SPDX-License-Identifier: MIT
+#
+# Kernel config fragments for vdkr/vpdmn:
+# - 9P filesystem for virtio-9p file sharing (volume mounts)
+# - Squashfs and overlayfs for rootfs images
+#
+# Only applied when "vcontainer" is in DISTRO_FEATURES.
+
+FILESEXTRAPATHS:prepend := "${THISDIR}/files:"
+
+SRC_URI += "${@bb.utils.contains('DISTRO_FEATURES', 'vcontainer', 'file://9p.cfg file://squashfs.cfg', '', d)}"