vcontainer: generalize init scripts for pluggable hypervisor backends

Make preinit and guest init scripts hypervisor-agnostic:
- vcontainer-preinit.sh: add vcontainer.init= cmdline parameter for
  init script selection and vcontainer.blk= for block device prefix
  (QEMU uses /dev/vda, Xen uses /dev/xvda)
- vdkr-init.sh, vpdmn-init.sh: use NINE_P_TRANSPORT variable for 9p
  mount transport (virtio for QEMU, xen for Xen)

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

3 files changed, 22 insertions, 15 deletions

diff --git a/recipes-containers/vcontainer/files/vcontainer-preinit.sh b/recipes-containers/vcontainer/files/vcontainer-preinit.sh
index 6f1b7e09..7d4e7072 100644
--- a/recipes-containers/vcontainer/files/vcontainer-preinit.sh
+++ b/recipes-containers/vcontainer/files/vcontainer-preinit.sh
@@ -19,11 +19,15 @@ mount -t proc proc /proc
 mount -t sysfs sysfs /sys
 mount -t devtmpfs devtmpfs /dev
 
-# Check for quiet mode (interactive)
+# Check for quiet mode, block device prefix, and init script selection
 QUIET=0
+BLK_PREFIX="vd"
+INIT_SCRIPT="/init"
 for param in $(cat /proc/cmdline 2>/dev/null); do
     case "$param" in
         docker_interactive=1) QUIET=1 ;;
+        vcontainer.blk=*) BLK_PREFIX="${param#vcontainer.blk=}" ;;
+        vcontainer.init=*) INIT_SCRIPT="${param#vcontainer.init=}" ;;
     esac
 done
 
@@ -39,11 +43,11 @@ sleep 2
 
 # Show available block devices
 log "Block devices:"
-[ "$QUIET" = "0" ] && ls -la /dev/vd* 2>/dev/null || log "No virtio block devices found"
+[ "$QUIET" = "0" ] && ls -la /dev/${BLK_PREFIX}* 2>/dev/null || log "No /dev/${BLK_PREFIX}* block devices found"
 
-# The rootfs.img is always the first virtio-blk device (/dev/vda)
-# Additional devices (input, state) come after
-ROOTFS_DEV="/dev/vda"
+# The rootfs.img is always the first block device
+# QEMU: /dev/vda, Xen: /dev/xvda
+ROOTFS_DEV="/dev/${BLK_PREFIX}a"
 
 if [ ! -b "$ROOTFS_DEV" ]; then
     echo "ERROR: Rootfs device $ROOTFS_DEV not found!"
@@ -119,9 +123,12 @@ mount --move /dev /mnt/root/dev
 # 2. chroot into it
 # 3. Execute the new init
 # 4. Delete everything in the old initramfs
-log "Switching to real root..."
+log "Switching to real root (init: $INIT_SCRIPT)..."
 
-if [ -x /mnt/root/init ]; then
+if [ -x "/mnt/root${INIT_SCRIPT}" ]; then
+    exec switch_root /mnt/root "$INIT_SCRIPT"
+elif [ -x /mnt/root/init ]; then
+    log "WARNING: $INIT_SCRIPT not found, falling back to /init"
     exec switch_root /mnt/root /init
 elif [ -x /mnt/root/sbin/init ]; then
     exec switch_root /mnt/root /sbin/init
diff --git a/recipes-containers/vcontainer/files/vdkr-init.sh b/recipes-containers/vcontainer/files/vdkr-init.sh
index a993aca4..e1e869b2 100755
--- a/recipes-containers/vcontainer/files/vdkr-init.sh
+++ b/recipes-containers/vcontainer/files/vdkr-init.sh
@@ -652,13 +652,13 @@ setup_cgroups
 # Parse kernel command line
 parse_cmdline
 
-# Mount virtio-9p share if available (for fast storage output in batch-import mode)
+# Mount 9p share if available (for fast storage output in batch-import mode)
 if [ "$RUNTIME_9P" = "1" ]; then
     mkdir -p /mnt/share
-    if mount -t 9p -o trans=virtio,version=9p2000.L,cache=none ${VCONTAINER_SHARE_NAME} /mnt/share 2>/dev/null; then
-        log "Mounted virtio-9p share at /mnt/share (fast I/O enabled)"
+    if mount -t 9p -o trans=${NINE_P_TRANSPORT},version=9p2000.L,cache=none ${VCONTAINER_SHARE_NAME} /mnt/share 2>/dev/null; then
+        log "Mounted 9p share at /mnt/share (transport: ${NINE_P_TRANSPORT})"
     else
-        log "WARNING: Could not mount virtio-9p share, falling back to console output"
+        log "WARNING: Could not mount 9p share, falling back to console output"
         RUNTIME_9P="0"
     fi
 fi
diff --git a/recipes-containers/vcontainer/files/vpdmn-init.sh b/recipes-containers/vcontainer/files/vpdmn-init.sh
index 70acd8af..7f661102 100755
--- a/recipes-containers/vcontainer/files/vpdmn-init.sh
+++ b/recipes-containers/vcontainer/files/vpdmn-init.sh
@@ -164,13 +164,13 @@ setup_cgroups
 # Parse kernel command line
 parse_cmdline
 
-# Mount virtio-9p share if available (for fast storage output in batch-import mode)
+# Mount 9p share if available (for fast storage output in batch-import mode)
 if [ "$RUNTIME_9P" = "1" ]; then
     mkdir -p /mnt/share
-    if mount -t 9p -o trans=virtio,version=9p2000.L,cache=none ${VCONTAINER_SHARE_NAME} /mnt/share 2>/dev/null; then
-        log "Mounted virtio-9p share at /mnt/share (fast I/O enabled)"
+    if mount -t 9p -o trans=${NINE_P_TRANSPORT},version=9p2000.L,cache=none ${VCONTAINER_SHARE_NAME} /mnt/share 2>/dev/null; then
+        log "Mounted 9p share at /mnt/share (transport: ${NINE_P_TRANSPORT})"
     else
-        log "WARNING: Could not mount virtio-9p share, falling back to console output"
+        log "WARNING: Could not mount 9p share, falling back to console output"
         RUNTIME_9P="0"
     fi
 fi