vcontainer: add tiny initramfs image infrastructure

Add proper Yocto image recipes for the tiny initramfs used by
vdkr/vpdmn in the switch_root boot flow:

- vcontainer-tiny-initramfs-image.inc: Shared image configuration
- vcontainer-preinit_1.0.bb: Preinit script package (shared)
- vdkr-tiny-initramfs-image.bb: Tiny initramfs for vdkr
- vpdmn-tiny-initramfs-image.bb: Tiny initramfs for vpdmn

The tiny initramfs contains only busybox and a preinit script that:
1. Mounts devtmpfs, proc, sysfs
2. Mounts the squashfs rootfs.img from /dev/vda
3. Creates tmpfs overlay for writes
4. Performs switch_root to the real rootfs

This replaces ad-hoc file extraction with proper image-based builds,
improving reproducibility and maintainability.

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

1 files changed, 13 insertions, 0 deletions

diff --git a/recipes-containers/vcontainer/vdkr-tiny-initramfs-image.bb b/recipes-containers/vcontainer/vdkr-tiny-initramfs-image.bb
new file mode 100644
index 00000000..42aa8637
--- /dev/null
+++ b/recipes-containers/vcontainer/vdkr-tiny-initramfs-image.bb
@@ -0,0 +1,13 @@
+# SPDX-FileCopyrightText: Copyright (C) 2025 Bruce Ashfield
+#
+# SPDX-License-Identifier: MIT
+#
+# vdkr-tiny-initramfs-image.bb - Tiny initramfs for vdkr
+#
+# Build with:
+#   bitbake mc:vruntime-aarch64:vdkr-tiny-initramfs-image
+#   bitbake mc:vruntime-x86-64:vdkr-tiny-initramfs-image
+#
+# Output: ${DEPLOY_DIR_IMAGE}/vdkr-tiny-initramfs-image-${MACHINE}.cpio.gz
+
+require vcontainer-tiny-initramfs-image.inc