From 39732488ef049c23957fa5cc47cb9633b0dda231 Mon Sep 17 00:00:00 2001
From: Adolfo Delorenzo <adelorenzo@oe74.net>
Date: Wed, 11 Feb 2026 23:13:31 -0600
Subject: [PATCH] feat: custom kernel build + boot fixes for working container
 runtime

Build a custom Tiny Core 17.0 kernel (6.18.2) with missing configs
that the stock kernel lacks for container workloads:
- CONFIG_CGROUP_BPF=y (cgroup v2 device control via BPF)
- CONFIG_DEVTMPFS=y (auto-create /dev device nodes)
- CONFIG_DEVTMPFS_MOUNT=y (auto-mount devtmpfs)
- CONFIG_MEMCG=y (memory cgroup controller for memory.max)
- CONFIG_CFS_BANDWIDTH=y (CPU bandwidth throttling for cpu.max)

Also strips unnecessary subsystems (sound, GPU, wireless, Bluetooth,
KVM, etc.) for minimal footprint on a headless K8s edge appliance.

Init system fixes for successful boot-to-running-pods:
- Add switch_root in init.sh to escape initramfs (runc pivot_root)
- Add mountpoint guards in 00-early-mount.sh (skip if already mounted)
- Create essential device nodes after switch_root (kmsg, console, etc.)
- Enable cgroup v2 controller delegation with init process isolation
- Mount BPF filesystem for cgroup v2 device control
- Add mknod fallback from sysfs in 20-persistent-mount.sh for /dev/vda
- Move KubeSolo binary to /usr/bin (avoid /usr/local bind mount hiding)
- Generate /etc/machine-id in 60-hostname.sh (kubelet requires it)
- Pre-initialize iptables tables before kube-proxy starts
- Add nft_reject, nft_fib, xt_nfacct to kernel modules list

Build system changes:
- New build-kernel.sh script for custom kernel compilation
- Dockerfile.builder adds kernel build deps (flex, bison, libelf, etc.)
- Selective kernel module install (only modules.list + transitive deps)
- Install iptables-nft (xtables-nft-multi) + shared libs in rootfs

Tested: ISO boots in QEMU, node reaches Ready in ~35s, CoreDNS and
local-path-provisioner pods start and run successfully.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>
---
 Makefile                          |  11 +-
 build/Dockerfile.builder          |  27 +++-
 build/config/modules.list         |  84 ++++++++---
 build/scripts/build-kernel.sh     | 209 ++++++++++++++++++++++++++
 build/scripts/fetch-components.sh | 132 +++++++++++++---
 build/scripts/inject-kubesolo.sh  | 242 +++++++++++++++++++++++++++++-
 init/init.sh                      |  33 ++++
 init/lib/00-early-mount.sh        |  69 +++++++--
 init/lib/20-persistent-mount.sh   |  15 ++
 init/lib/50-network.sh            |  10 +-
 init/lib/60-hostname.sh           |  13 ++
 init/lib/90-kubesolo.sh           |  15 +-
 init/lib/functions.sh             |  11 +-
 13 files changed, 794 insertions(+), 77 deletions(-)
 create mode 100755 build/scripts/build-kernel.sh

diff --git a/Makefile b/Makefile
index b5dc9c9..317d2e2 100644
--- a/Makefile
+++ b/Makefile
@@ -1,4 +1,4 @@
-.PHONY: all fetch build-cloudinit build-update-agent build-cross rootfs initramfs \
+.PHONY: all fetch kernel build-cloudinit build-update-agent build-cross rootfs initramfs \
        iso disk-image oci-image \
        test-boot test-k8s test-persistence test-deploy test-storage test-all \
        test-cloudinit test-update-agent \
@@ -30,6 +30,10 @@ fetch:
 # =============================================================================
 # Build stages
 # =============================================================================
+kernel:
+	@echo "==> Building custom kernel (CONFIG_CGROUP_BPF=y)..."
+	$(BUILD_DIR)/scripts/build-kernel.sh
+
 build-cloudinit:
 	@echo "==> Building cloud-init binary..."
 	$(BUILD_DIR)/scripts/build-cloudinit.sh
@@ -38,7 +42,7 @@ build-update-agent:
 	@echo "==> Building update agent..."
 	$(BUILD_DIR)/scripts/build-update-agent.sh
 
-rootfs: fetch build-cloudinit build-update-agent
+rootfs: fetch kernel build-cloudinit build-update-agent
 	@echo "==> Preparing rootfs..."
 	$(BUILD_DIR)/scripts/extract-core.sh
 	$(BUILD_DIR)/scripts/inject-kubesolo.sh
@@ -176,7 +180,7 @@ docker-build:
 	docker run --rm --privileged \
 		-v $(PWD)/$(OUTPUT_DIR):/output \
 		-v $(PWD)/$(CACHE_DIR):/cache \
-		kubesolo-os-builder make iso OUTPUT_DIR=/output CACHE_DIR=/cache
+		kubesolo-os-builder iso OUTPUT_DIR=/output CACHE_DIR=/cache
 
 # =============================================================================
 # Cleanup
@@ -197,6 +201,7 @@ help:
 	@echo ""
 	@echo "Build targets:"
 	@echo "  make fetch              Download Tiny Core ISO, KubeSolo, dependencies"
+	@echo "  make kernel             Build custom kernel with CONFIG_CGROUP_BPF=y"
 	@echo "  make build-cloudinit    Build cloud-init Go binary"
 	@echo "  make build-update-agent Build update agent Go binary"
 	@echo "  make rootfs             Extract + prepare rootfs with KubeSolo"
diff --git a/build/Dockerfile.builder b/build/Dockerfile.builder
index cbcb1a2..de008d3 100644
--- a/build/Dockerfile.builder
+++ b/build/Dockerfile.builder
@@ -1,19 +1,30 @@
-FROM ubuntu:24.04
+FROM --platform=linux/amd64 ubuntu:24.04
 
 ENV DEBIAN_FRONTEND=noninteractive
 
+# Install build tools + kernel build dependencies
 RUN apt-get update && apt-get install -y --no-install-recommends \
     bash \
-    bsdtar \
+    bc \
+    bison \
+    build-essential \
+    ca-certificates \
     cpio \
     curl \
     dosfstools \
+    dwarves \
     e2fsprogs \
     fdisk \
+    file \
+    flex \
     genisoimage \
     gzip \
     isolinux \
-    losetup \
+    iptables \
+    kmod \
+    libarchive-tools \
+    libelf-dev \
+    libssl-dev \
     make \
     parted \
     squashfs-tools \
@@ -25,10 +36,18 @@ RUN apt-get update && apt-get install -y --no-install-recommends \
     xz-utils \
     && rm -rf /var/lib/apt/lists/*
 
+# Install Go (for building cloud-init and update agent)
+ARG GO_VERSION=1.24.0
+RUN curl -fsSL "https://go.dev/dl/go${GO_VERSION}.linux-amd64.tar.gz" \
+    | tar -C /usr/local -xzf -
+ENV PATH="/usr/local/go/bin:${PATH}"
+
 WORKDIR /build
 COPY . /build
 
-RUN chmod +x build/scripts/*.sh build/config/*.sh
+RUN chmod +x build/scripts/*.sh build/config/*.sh \
+    && chmod +x hack/*.sh 2>/dev/null || true \
+    && chmod +x test/qemu/*.sh test/integration/*.sh test/kernel/*.sh 2>/dev/null || true
 
 ENTRYPOINT ["/usr/bin/make"]
 CMD ["iso"]
diff --git a/build/config/modules.list b/build/config/modules.list
index 04f7d76..86a4608 100644
--- a/build/config/modules.list
+++ b/build/config/modules.list
@@ -1,30 +1,78 @@
 # Kernel modules loaded at boot by init
 # One module per line. Lines starting with # are ignored.
-# Modules are loaded in order listed.
+# Modules are loaded in order listed — dependencies must come first.
 
-# Networking — bridge and netfilter (required for K8s pod networking)
-br_netfilter
-bridge
-veth
-vxlan
+# Network device drivers (loaded early so interfaces are available)
+e1000
+e1000e
+virtio_net
 
-# Netfilter / iptables (required for kube-proxy and service routing)
-ip_tables
-iptable_nat
-iptable_filter
-iptable_mangle
-nf_nat
-nf_conntrack
-nf_conntrack_netlink
+# Virtio support (for VMs — block, entropy)
+virtio_blk
+virtio_rng
 
 # Filesystem — overlay (required for containerd)
 overlay
 
-# Conntrack (required for K8s services)
-nf_conntrack
+# Netfilter dependencies (must load before conntrack)
+nf_defrag_ipv4
+nf_defrag_ipv6
 
-# Optional — useful for CNI plugins and diagnostics
-tun
+# Netfilter / connection tracking (required for kube-proxy)
+nf_conntrack
+nf_nat
+nf_conntrack_netlink
+
+# nftables (modern iptables backend — kernel 6.18 uses nf_tables, not ip_tables)
+nf_tables
+nft_compat
+nft_chain_nat
+nft_ct
+nft_masq
+nft_nat
+nft_redir
+
+# Netfilter xt match/target modules (used by kube-proxy iptables rules via nft_compat)
+xt_conntrack
+xt_MASQUERADE
+xt_mark
+xt_comment
+xt_multiport
+xt_nat
+xt_addrtype
+xt_connmark
+xt_REDIRECT
+xt_recent
+xt_statistic
+xt_set
+
+# nft extras (reject, fib — used by kube-proxy nf_tables rules)
+nft_reject
+nft_reject_ipv4
+nft_reject_ipv6
+nft_fib
+nft_fib_ipv4
+nft_fib_ipv6
+
+# Reject targets (used by kube-proxy iptables-restore rules)
+nf_reject_ipv4
+nf_reject_ipv6
+ipt_REJECT
+ip6t_REJECT
+
+# nfacct extension (kube-proxy probes for it)
+xt_nfacct
+
+# Networking — bridge and netfilter (required for K8s pod networking)
+# Load order: llc → stp → bridge → br_netfilter
+llc
+stp
+bridge
+br_netfilter
+veth
+vxlan
+
+# IPVS — useful for kube-proxy IPVS mode and CNI plugins
 ip_vs
 ip_vs_rr
 ip_vs_wrr
diff --git a/build/scripts/build-kernel.sh b/build/scripts/build-kernel.sh
new file mode 100755
index 0000000..17a1982
--- /dev/null
+++ b/build/scripts/build-kernel.sh
@@ -0,0 +1,209 @@
+#!/bin/bash
+# build-kernel.sh — Build custom Tiny Core kernel with CONFIG_CGROUP_BPF=y
+#
+# The stock Tiny Core 17.0 kernel (6.18.2-tinycore64) lacks CONFIG_CGROUP_BPF,
+# which is required for cgroup v2 device control in runc/containerd.
+# This script downloads the TC-patched kernel source, enables CONFIG_CGROUP_BPF,
+# and builds vmlinuz + modules.
+#
+# Output is cached in $CACHE_DIR/custom-kernel/ and reused across builds.
+set -euo pipefail
+
+SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
+PROJECT_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"
+CACHE_DIR="${CACHE_DIR:-$PROJECT_ROOT/build/cache}"
+
+# shellcheck source=../config/versions.env
+. "$SCRIPT_DIR/../config/versions.env"
+
+KVER="6.18.2-tinycore64"
+KERNEL_BASE_URL="https://distro.ibiblio.org/tinycorelinux/${TINYCORE_VERSION%%.*}.x/${TINYCORE_ARCH}/release/src/kernel"
+KERNEL_SRC_URL="${KERNEL_BASE_URL}/linux-6.18.2-patched.tar.xz"
+KERNEL_CFG_URL="${KERNEL_BASE_URL}/config-${KVER}"
+
+CUSTOM_KERNEL_DIR="$CACHE_DIR/custom-kernel"
+CUSTOM_VMLINUZ="$CUSTOM_KERNEL_DIR/vmlinuz"
+CUSTOM_MODULES="$CUSTOM_KERNEL_DIR/modules"
+
+mkdir -p "$CACHE_DIR" "$CUSTOM_KERNEL_DIR"
+
+# --- Skip if already built ---
+if [ -f "$CUSTOM_VMLINUZ" ] && [ -d "$CUSTOM_MODULES/lib/modules/$KVER" ]; then
+    echo "==> Custom kernel already built (cached)"
+    echo "    vmlinuz: $CUSTOM_VMLINUZ ($(du -h "$CUSTOM_VMLINUZ" | cut -f1))"
+    MOD_COUNT=$(find "$CUSTOM_MODULES/lib/modules/$KVER" -name '*.ko*' | wc -l)
+    echo "    Modules: $MOD_COUNT modules in $CUSTOM_MODULES/lib/modules/$KVER"
+    exit 0
+fi
+
+echo "==> Building custom kernel with CONFIG_CGROUP_BPF=y..."
+echo "    Kernel version: $KVER"
+
+# --- Download kernel source ---
+KERNEL_SRC_ARCHIVE="$CACHE_DIR/linux-6.18.2-patched.tar.xz"
+if [ ! -f "$KERNEL_SRC_ARCHIVE" ]; then
+    echo "==> Downloading kernel source (~149 MB)..."
+    echo "    URL: $KERNEL_SRC_URL"
+    wget -q --show-progress -O "$KERNEL_SRC_ARCHIVE" "$KERNEL_SRC_URL" 2>/dev/null || \
+        curl -fSL "$KERNEL_SRC_URL" -o "$KERNEL_SRC_ARCHIVE"
+    echo "    Downloaded: $(du -h "$KERNEL_SRC_ARCHIVE" | cut -f1)"
+else
+    echo "==> Kernel source already cached: $(du -h "$KERNEL_SRC_ARCHIVE" | cut -f1)"
+fi
+
+# --- Download stock config ---
+KERNEL_CFG="$CACHE_DIR/config-${KVER}"
+if [ ! -f "$KERNEL_CFG" ]; then
+    echo "==> Downloading stock kernel config..."
+    echo "    URL: $KERNEL_CFG_URL"
+    wget -q -O "$KERNEL_CFG" "$KERNEL_CFG_URL" 2>/dev/null || \
+        curl -fSL "$KERNEL_CFG_URL" -o "$KERNEL_CFG"
+else
+    echo "==> Stock kernel config already cached"
+fi
+
+# --- Extract source ---
+# IMPORTANT: Must extract on a case-sensitive filesystem. The kernel source has
+# files that differ only by case (e.g., xt_mark.h vs xt_MARK.h). If the cache
+# is on macOS (case-insensitive APFS), extraction silently loses files.
+# Use /tmp inside the container (ext4, case-sensitive) for the build.
+KERNEL_BUILD_DIR="/tmp/kernel-build"
+rm -rf "$KERNEL_BUILD_DIR"
+mkdir -p "$KERNEL_BUILD_DIR"
+
+echo "==> Extracting kernel source (case-sensitive filesystem)..."
+tar -xf "$KERNEL_SRC_ARCHIVE" -C "$KERNEL_BUILD_DIR"
+
+# Find the extracted source directory (could be linux-6.18.2 or linux-6.18.2-patched)
+KERNEL_SRC_DIR=$(find "$KERNEL_BUILD_DIR" -maxdepth 1 -type d -name 'linux-*' | head -1)
+if [ -z "$KERNEL_SRC_DIR" ]; then
+    echo "ERROR: Could not find kernel source directory after extraction"
+    ls -la "$KERNEL_BUILD_DIR"/
+    exit 1
+fi
+echo "    Source dir: $(basename "$KERNEL_SRC_DIR")"
+
+cd "$KERNEL_SRC_DIR"
+
+# --- Apply stock config + enable CONFIG_CGROUP_BPF ---
+echo "==> Applying stock Tiny Core config..."
+cp "$KERNEL_CFG" .config
+
+echo "==> Enabling required kernel configs..."
+./scripts/config --enable CONFIG_CGROUP_BPF
+./scripts/config --enable CONFIG_DEVTMPFS
+./scripts/config --enable CONFIG_DEVTMPFS_MOUNT
+./scripts/config --enable CONFIG_MEMCG
+./scripts/config --enable CONFIG_CFS_BANDWIDTH
+
+# --- Strip unnecessary subsystems for smallest footprint ---
+# This is a headless K8s edge appliance — no sound, GPU, wireless, etc.
+echo "==> Disabling unnecessary subsystems for minimal footprint..."
+
+# Sound subsystem (not needed on headless appliance)
+./scripts/config --disable SOUND
+
+# GPU/DRM (serial console only, no display)
+./scripts/config --disable DRM
+
+# KVM hypervisor (this IS the guest/bare metal, not a hypervisor)
+./scripts/config --disable KVM
+
+# Media/camera/TV/radio (not needed)
+./scripts/config --disable MEDIA_SUPPORT
+
+# Wireless networking (wired edge device)
+./scripts/config --disable WIRELESS
+./scripts/config --disable WLAN
+./scripts/config --disable CFG80211
+
+# Bluetooth (not needed)
+./scripts/config --disable BT
+
+# NFC (not needed)
+./scripts/config --disable NFC
+
+# Infiniband (not needed on edge)
+./scripts/config --disable INFINIBAND
+
+# PCMCIA (legacy, not needed)
+./scripts/config --disable PCMCIA
+
+# Amateur radio (not needed)
+./scripts/config --disable HAMRADIO
+
+# ISDN (not needed)
+./scripts/config --disable ISDN
+
+# ATM networking (not needed)
+./scripts/config --disable ATM
+
+# Joystick/gamepad (not needed)
+./scripts/config --disable INPUT_JOYSTICK
+./scripts/config --disable INPUT_TABLET
+
+# FPGA (not needed)
+./scripts/config --disable FPGA
+
+# Resolve dependencies (olddefconfig accepts defaults for new options)
+make olddefconfig
+
+# Verify CONFIG_CGROUP_BPF is set
+if grep -q 'CONFIG_CGROUP_BPF=y' .config; then
+    echo "    CONFIG_CGROUP_BPF=y confirmed in .config"
+else
+    echo "ERROR: CONFIG_CGROUP_BPF not set after olddefconfig"
+    grep 'CGROUP_BPF' .config || echo "    (CGROUP_BPF not found in .config)"
+    echo ""
+    echo "Prerequisites check:"
+    grep -E 'CONFIG_BPF=|CONFIG_BPF_SYSCALL=' .config || echo "    BPF not found"
+    exit 1
+fi
+
+# Show what changed
+echo "    Config diff from stock:"
+diff "$KERNEL_CFG" .config | grep '^[<>]' | head -20 || echo "    (no differences beyond CGROUP_BPF)"
+
+# --- Build kernel + modules ---
+NPROC=$(nproc 2>/dev/null || echo 4)
+echo ""
+echo "==> Building kernel (${NPROC} parallel jobs)..."
+echo "    This may take 15-25 minutes..."
+
+make -j"$NPROC" bzImage modules 2>&1
+
+echo "==> Kernel build complete"
+
+# --- Install to staging ---
+echo "==> Installing vmlinuz..."
+cp arch/x86/boot/bzImage "$CUSTOM_VMLINUZ"
+
+echo "==> Installing modules (stripped)..."
+rm -rf "$CUSTOM_MODULES"
+mkdir -p "$CUSTOM_MODULES"
+make INSTALL_MOD_STRIP=1 modules_install INSTALL_MOD_PATH="$CUSTOM_MODULES"
+
+# Remove build/source symlinks (they point to the build dir which won't exist in rootfs)
+rm -f "$CUSTOM_MODULES/lib/modules/$KVER/build"
+rm -f "$CUSTOM_MODULES/lib/modules/$KVER/source"
+
+# Run depmod to generate proper module dependency files
+echo "==> Running depmod..."
+depmod -a -b "$CUSTOM_MODULES" "$KVER" 2>/dev/null || true
+
+# Save the final config for reference
+cp .config "$CUSTOM_KERNEL_DIR/.config"
+
+# --- Clean up build dir (large, ~1.5 GB) ---
+echo "==> Cleaning kernel build directory..."
+cd /
+rm -rf "$KERNEL_BUILD_DIR"
+
+# --- Summary ---
+echo ""
+echo "==> Custom kernel build complete:"
+echo "    vmlinuz:      $CUSTOM_VMLINUZ ($(du -h "$CUSTOM_VMLINUZ" | cut -f1))"
+MOD_COUNT=$(find "$CUSTOM_MODULES/lib/modules/$KVER" -name '*.ko*' | wc -l)
+echo "    Modules:      $MOD_COUNT modules"
+echo "    Modules size: $(du -sh "$CUSTOM_MODULES/lib/modules/$KVER" | cut -f1)"
+echo ""
diff --git a/build/scripts/fetch-components.sh b/build/scripts/fetch-components.sh
index dc44289..77b08c0 100755
--- a/build/scripts/fetch-components.sh
+++ b/build/scripts/fetch-components.sh
@@ -31,36 +31,126 @@ else
 fi
 
 # --- KubeSolo ---
-KUBESOLO_INSTALLER="$CACHE_DIR/install-kubesolo.sh"
+KUBESOLO_VERSION="${KUBESOLO_VERSION:-v1.1.0}"
 KUBESOLO_BIN="$CACHE_DIR/kubesolo"
 
 if [ -f "$KUBESOLO_BIN" ]; then
     echo "==> KubeSolo binary already cached: $KUBESOLO_BIN"
 else
-    echo "==> Downloading KubeSolo installer..."
-    curl -sfL "$KUBESOLO_INSTALL_URL" -o "$KUBESOLO_INSTALLER"
+    echo "==> Downloading KubeSolo ${KUBESOLO_VERSION}..."
 
-    echo "==> Extracting KubeSolo binary..."
-    echo "    NOTE: The installer normally runs 'install'. We extract the binary URL instead."
-    echo "    For Phase 1 PoC, install KubeSolo on a host and copy the binary."
-    echo ""
-    echo "    Manual step required:"
-    echo "    1. On a Linux x86_64 host: curl -sfL https://get.kubesolo.io | sudo sh -"
-    echo "    2. Copy /usr/local/bin/kubesolo to: $KUBESOLO_BIN"
-    echo "    3. Re-run: make rootfs"
-    echo ""
+    # Determine architecture
+    ARCH="${TARGET_ARCH:-amd64}"
+    OS="linux"
 
-    # Try to extract download URL from installer script
-    BINARY_URL=$(grep -oP 'https://[^ ]+kubesolo[^ ]+' "$KUBESOLO_INSTALLER" 2>/dev/null | head -1 || true)
-    if [ -n "$BINARY_URL" ]; then
-        echo "    Attempting direct download from: $BINARY_URL"
-        curl -sfL "$BINARY_URL" -o "$KUBESOLO_BIN" && chmod +x "$KUBESOLO_BIN" || {
-            echo "    Direct download failed. Use manual step above."
-        }
+    # Build download URL from GitHub releases
+    # Available variants: kubesolo-v1.1.0-linux-amd64.tar.gz, kubesolo-v1.1.0-linux-amd64-musl.tar.gz
+    # We use the musl variant for maximum compatibility with Tiny Core Linux (musl-based)
+    BIN_URL="https://github.com/portainer/kubesolo/releases/download/${KUBESOLO_VERSION}/kubesolo-${KUBESOLO_VERSION}-${OS}-${ARCH}-musl.tar.gz"
+    BIN_URL_FALLBACK="https://github.com/portainer/kubesolo/releases/download/${KUBESOLO_VERSION}/kubesolo-${KUBESOLO_VERSION}-${OS}-${ARCH}.tar.gz"
+
+    TEMP_DIR=$(mktemp -d)
+    trap "rm -rf '$TEMP_DIR'" EXIT
+
+    echo "    URL: $BIN_URL"
+    if curl -fSL "$BIN_URL" -o "$TEMP_DIR/kubesolo.tar.gz" 2>/dev/null; then
+        echo "    Downloaded musl variant"
+    elif curl -fSL "$BIN_URL_FALLBACK" -o "$TEMP_DIR/kubesolo.tar.gz" 2>/dev/null; then
+        echo "    Downloaded glibc variant (fallback)"
+    else
+        echo "ERROR: Failed to download KubeSolo from GitHub."
+        echo "  Tried: $BIN_URL"
+        echo "  Tried: $BIN_URL_FALLBACK"
+        echo ""
+        echo "  Manual step:"
+        echo "    1. Download from: https://github.com/portainer/kubesolo/releases"
+        echo "    2. Extract and copy binary to: $KUBESOLO_BIN"
+        echo "    3. Re-run: make rootfs"
+        exit 1
     fi
 
-    if [ -f "$KUBESOLO_BIN" ]; then
-        echo "==> KubeSolo binary: $KUBESOLO_BIN ($(du -h "$KUBESOLO_BIN" | cut -f1))"
+    # Extract binary from tarball
+    tar -xzf "$TEMP_DIR/kubesolo.tar.gz" -C "$TEMP_DIR"
+
+    # Find the kubesolo binary in extracted contents
+    FOUND_BIN=$(find "$TEMP_DIR" -name "kubesolo" -type f ! -name "*.tar.gz" | head -1)
+    if [ -z "$FOUND_BIN" ]; then
+        echo "ERROR: Could not find kubesolo binary in extracted archive"
+        echo "  Archive contents:"
+        ls -la "$TEMP_DIR"/
+        exit 1
+    fi
+
+    cp "$FOUND_BIN" "$KUBESOLO_BIN"
+    chmod +x "$KUBESOLO_BIN"
+
+    trap - EXIT
+    rm -rf "$TEMP_DIR"
+
+    echo "==> KubeSolo binary: $KUBESOLO_BIN ($(du -h "$KUBESOLO_BIN" | cut -f1))"
+fi
+
+# --- Tiny Core kernel module extensions (netfilter, iptables) ---
+# The base Tiny Core initramfs does NOT include netfilter kernel modules.
+# They are distributed as separate TCZ (squashfs) extensions.
+# KubeSolo requires netfilter for kube-proxy, iptables NAT, conntrack, etc.
+
+# Detect kernel version from the cached ISO
+KVER=""
+if [ -f "$TC_ISO" ]; then
+    # Try to detect kernel version from ISO without mounting
+    # Tiny Core 17.0 uses 6.18.2-tinycore64
+    KVER="6.18.2-tinycore64"
+fi
+
+NETFILTER_TCZ="$CACHE_DIR/ipv6-netfilter-${KVER}.tcz"
+NETFILTER_TCZ_URL="https://distro.ibiblio.org/tinycorelinux/${TINYCORE_VERSION%%.*}.x/${TINYCORE_ARCH}/tcz/ipv6-netfilter-${KVER}.tcz"
+
+if [ -f "$NETFILTER_TCZ" ]; then
+    echo "==> Netfilter modules already cached: $NETFILTER_TCZ"
+else
+    echo "==> Downloading netfilter kernel modules (ipv6-netfilter-${KVER}.tcz)..."
+    echo "    URL: $NETFILTER_TCZ_URL"
+    if wget -q --show-progress -O "$NETFILTER_TCZ" "$NETFILTER_TCZ_URL" 2>/dev/null || \
+       curl -fSL "$NETFILTER_TCZ_URL" -o "$NETFILTER_TCZ" 2>/dev/null; then
+        echo "==> Downloaded: $NETFILTER_TCZ ($(du -h "$NETFILTER_TCZ" | cut -f1))"
+    else
+        echo "WARN: Failed to download netfilter modules. kube-proxy may not work."
+        rm -f "$NETFILTER_TCZ"
+    fi
+fi
+
+NET_BRIDGING_TCZ="$CACHE_DIR/net-bridging-${KVER}.tcz"
+NET_BRIDGING_TCZ_URL="https://distro.ibiblio.org/tinycorelinux/${TINYCORE_VERSION%%.*}.x/${TINYCORE_ARCH}/tcz/net-bridging-${KVER}.tcz"
+
+if [ -f "$NET_BRIDGING_TCZ" ]; then
+    echo "==> Net-bridging modules already cached: $NET_BRIDGING_TCZ"
+else
+    echo "==> Downloading net-bridging kernel modules (net-bridging-${KVER}.tcz)..."
+    echo "    URL: $NET_BRIDGING_TCZ_URL"
+    if wget -q --show-progress -O "$NET_BRIDGING_TCZ" "$NET_BRIDGING_TCZ_URL" 2>/dev/null || \
+       curl -fSL "$NET_BRIDGING_TCZ_URL" -o "$NET_BRIDGING_TCZ" 2>/dev/null; then
+        echo "==> Downloaded: $NET_BRIDGING_TCZ ($(du -h "$NET_BRIDGING_TCZ" | cut -f1))"
+    else
+        echo "WARN: Failed to download net-bridging modules. CNI bridge may not work."
+        rm -f "$NET_BRIDGING_TCZ"
+    fi
+fi
+
+IPTABLES_TCZ="$CACHE_DIR/iptables.tcz"
+IPTABLES_TCZ_URL="https://distro.ibiblio.org/tinycorelinux/${TINYCORE_VERSION%%.*}.x/${TINYCORE_ARCH}/tcz/iptables.tcz"
+
+if [ -f "$IPTABLES_TCZ" ]; then
+    echo "==> iptables userspace already cached: $IPTABLES_TCZ"
+else
+    echo "==> Downloading iptables userspace tools..."
+    echo "    URL: $IPTABLES_TCZ_URL"
+    if wget -q --show-progress -O "$IPTABLES_TCZ" "$IPTABLES_TCZ_URL" 2>/dev/null || \
+       curl -fSL "$IPTABLES_TCZ_URL" -o "$IPTABLES_TCZ" 2>/dev/null; then
+        echo "==> Downloaded: $IPTABLES_TCZ ($(du -h "$IPTABLES_TCZ" | cut -f1))"
+    else
+        echo "WARN: Failed to download iptables. KubeSolo bundles its own but this is a fallback."
+        rm -f "$IPTABLES_TCZ"
     fi
 fi
 
diff --git a/build/scripts/inject-kubesolo.sh b/build/scripts/inject-kubesolo.sh
index f046778..f1236bf 100755
--- a/build/scripts/inject-kubesolo.sh
+++ b/build/scripts/inject-kubesolo.sh
@@ -25,15 +25,19 @@ fi
 echo "==> Injecting KubeSolo into rootfs..."
 
 # --- 1. KubeSolo binary ---
-mkdir -p "$ROOTFS/usr/local/bin"
-cp "$KUBESOLO_BIN" "$ROOTFS/usr/local/bin/kubesolo"
-chmod +x "$ROOTFS/usr/local/bin/kubesolo"
+# Install to /usr/bin (NOT /usr/local/bin) because /usr/local is bind-mounted
+# from the data partition at boot, which would hide the binary.
+mkdir -p "$ROOTFS/usr/bin"
+cp "$KUBESOLO_BIN" "$ROOTFS/usr/bin/kubesolo"
+chmod +x "$ROOTFS/usr/bin/kubesolo"
 echo "    Installed KubeSolo binary ($(du -h "$KUBESOLO_BIN" | cut -f1))"
 
 # --- 2. Custom init system ---
 echo "    Installing init system..."
 
-# Main init
+# Main init — remove symlink first to avoid clobbering busybox
+# (Tiny Core has /sbin/init -> ../bin/busybox; cp follows symlinks)
+rm -f "$ROOTFS/sbin/init"
 cp "$PROJECT_ROOT/init/init.sh" "$ROOTFS/sbin/init"
 chmod +x "$ROOTFS/sbin/init"
 
@@ -83,7 +87,233 @@ else
     echo "    WARN: Update agent not found (run 'make build-update-agent' to build)"
 fi
 
-# --- 3. Kernel modules list ---
+# --- 3. Custom kernel or TCZ kernel modules ---
+# If a custom kernel was built (with CONFIG_CGROUP_BPF=y), use it.
+# Otherwise fall back to TCZ-extracted modules with manual modules.dep.
+CUSTOM_KERNEL_DIR="$CACHE_DIR/custom-kernel"
+CUSTOM_VMLINUZ="$CUSTOM_KERNEL_DIR/vmlinuz"
+CUSTOM_MODULES="$CUSTOM_KERNEL_DIR/modules"
+
+# Detect kernel version from rootfs
+KVER=""
+for d in "$ROOTFS"/lib/modules/*/; do
+    [ -d "$d" ] && KVER="$(basename "$d")" && break
+done
+
+if [ -z "$KVER" ]; then
+    echo "    WARN: Could not detect kernel version from rootfs"
+fi
+
+echo "    Kernel version: $KVER"
+
+if [ -f "$CUSTOM_VMLINUZ" ] && [ -d "$CUSTOM_MODULES/lib/modules/$KVER" ]; then
+    # =========================================================================
+    # Custom kernel path — selective module install (only what modules.list needs)
+    # =========================================================================
+    echo "    Using custom kernel (CONFIG_CGROUP_BPF=y)..."
+
+    # Replace vmlinuz
+    cp "$CUSTOM_VMLINUZ" "$ROOTFS_DIR/vmlinuz"
+    echo "    Installed custom vmlinuz ($(du -h "$CUSTOM_VMLINUZ" | cut -f1))"
+
+    # Selectively install ONLY modules from modules.list + their transitive deps.
+    # This keeps the initramfs minimal — no sound, GPU, SCSI, etc. modules.
+    echo "    Installing kernel modules (selective — modules.list + deps only)..."
+    CUSTOM_MOD_DIR="$CUSTOM_MODULES/lib/modules/$KVER"
+
+    rm -rf "$ROOTFS/lib/modules/$KVER"
+    mkdir -p "$ROOTFS/lib/modules/$KVER/kernel"
+
+    # Copy module metadata files (needed by modprobe)
+    for f in modules.builtin modules.builtin.modinfo modules.order \
+             modules.builtin.alias.bin modules.builtin.bin; do
+        [ -f "$CUSTOM_MOD_DIR/$f" ] && cp "$CUSTOM_MOD_DIR/$f" "$ROOTFS/lib/modules/$KVER/"
+    done
+
+    # Use modprobe --show-depends to resolve each module + its transitive deps
+    MODULES_LIST="$PROJECT_ROOT/build/config/modules.list"
+    NEEDED_MODS=$(mktemp)
+    while IFS= read -r mod; do
+        # Skip comments and blank lines
+        case "$mod" in \#*|"") continue ;; esac
+        mod=$(echo "$mod" | xargs)  # trim whitespace
+        [ -z "$mod" ] && continue
+
+        # modprobe -S <ver> -d <root> --show-depends <module> lists all deps in load order
+        # Output format: "insmod /path/to/module.ko" — extract path with awk
+        modprobe -S "$KVER" -d "$CUSTOM_MODULES" --show-depends "$mod" 2>/dev/null \
+            | awk '/^insmod/{print $2}' >> "$NEEDED_MODS" \
+            || echo "    WARN: modprobe could not resolve: $mod"
+    done < "$MODULES_LIST"
+
+    # Deduplicate and copy each needed module
+    sort -u "$NEEDED_MODS" | while IFS= read -r mod_path; do
+        mod_path=$(echo "$mod_path" | xargs)  # trim whitespace
+        [ -z "$mod_path" ] && continue
+        # mod_path is absolute (e.g., /path/to/custom-kernel/modules/lib/modules/KVER/kernel/...)
+        if [ ! -f "$mod_path" ]; then
+            echo "    WARN: module not found: $mod_path"
+            continue
+        fi
+        # Get the relative path under lib/modules/KVER/
+        rel_path="${mod_path#$CUSTOM_MOD_DIR/}"
+        dst="$ROOTFS/lib/modules/$KVER/$rel_path"
+        mkdir -p "$(dirname "$dst")"
+        cp "$mod_path" "$dst"
+    done
+    rm -f "$NEEDED_MODS"
+
+    # Run depmod on the selective module set to generate correct metadata
+    depmod -a -b "$ROOTFS" "$KVER" 2>/dev/null || true
+
+    MOD_COUNT=$(find "$ROOTFS/lib/modules/$KVER" -name '*.ko*' | wc -l)
+    MOD_SIZE=$(du -sh "$ROOTFS/lib/modules/$KVER" | cut -f1)
+    echo "    Installed $MOD_COUNT kernel modules ($MOD_SIZE) — minimal set"
+
+else
+    # =========================================================================
+    # Stock kernel path — extract TCZ modules + manual modules.dep
+    # =========================================================================
+    echo "    No custom kernel found, using stock kernel with TCZ modules..."
+
+    if [ -n "$KVER" ]; then
+        ROOTFS_MOD_DST="$ROOTFS/lib/modules/$KVER/kernel"
+
+        NETFILTER_TCZ="$CACHE_DIR/ipv6-netfilter-${KVER}.tcz"
+        if [ -f "$NETFILTER_TCZ" ]; then
+            echo "    Extracting netfilter modules from $(basename "$NETFILTER_TCZ")..."
+            TCZ_TMP=$(mktemp -d)
+            if command -v unsquashfs >/dev/null 2>&1; then
+                unsquashfs -d "$TCZ_TMP/content" "$NETFILTER_TCZ" >/dev/null 2>&1
+            else
+                echo "    ERROR: unsquashfs not found (install squashfs-tools)"
+                rm -rf "$TCZ_TMP"
+                exit 1
+            fi
+            TCZ_MOD_SRC="$TCZ_TMP/content/usr/local/lib/modules/$KVER/kernel"
+            if [ -d "$TCZ_MOD_SRC" ]; then
+                find "$TCZ_MOD_SRC" -name '*.ko.gz' | while IFS= read -r mod_file; do
+                    rel_path="${mod_file#$TCZ_MOD_SRC/}"
+                    dst_dir="$ROOTFS_MOD_DST/$(dirname "$rel_path")"
+                    mkdir -p "$dst_dir"
+                    cp "$mod_file" "$dst_dir/"
+                done
+                MOD_COUNT=$(find "$TCZ_MOD_SRC" -name '*.ko.gz' | wc -l)
+                echo "    Installed $MOD_COUNT kernel modules from netfilter TCZ"
+            fi
+            rm -rf "$TCZ_TMP"
+        else
+            echo "    WARN: Netfilter TCZ not found. kube-proxy may not work."
+        fi
+
+        NET_BRIDGING_TCZ="$CACHE_DIR/net-bridging-${KVER}.tcz"
+        if [ -f "$NET_BRIDGING_TCZ" ]; then
+            echo "    Extracting bridge modules from $(basename "$NET_BRIDGING_TCZ")..."
+            TCZ_TMP=$(mktemp -d)
+            unsquashfs -d "$TCZ_TMP/content" "$NET_BRIDGING_TCZ" >/dev/null 2>&1
+            TCZ_MOD_SRC="$TCZ_TMP/content/usr/local/lib/modules/$KVER/kernel"
+            if [ -d "$TCZ_MOD_SRC" ]; then
+                find "$TCZ_MOD_SRC" -name '*.ko.gz' | while IFS= read -r mod_file; do
+                    rel_path="${mod_file#$TCZ_MOD_SRC/}"
+                    dst_dir="$ROOTFS_MOD_DST/$(dirname "$rel_path")"
+                    mkdir -p "$dst_dir"
+                    cp "$mod_file" "$dst_dir/"
+                done
+                BR_COUNT=$(find "$TCZ_MOD_SRC" -name '*.ko.gz' | wc -l)
+                echo "    Installed $BR_COUNT kernel modules from net-bridging TCZ"
+            fi
+            rm -rf "$TCZ_TMP"
+        else
+            echo "    WARN: Net-bridging TCZ not found. CNI bridge networking may not work."
+        fi
+
+        # Manual modules.dep for stock kernel (Ubuntu's depmod can't handle TC's kernel)
+        MODULES_DEP="$ROOTFS/lib/modules/$KVER/modules.dep"
+        if [ -f "$MODULES_DEP" ]; then
+            echo "    Appending module entries to modules.dep..."
+            cat >> "$MODULES_DEP" << 'MODDEP'
+kernel/net/ipv6/ipv6.ko.gz:
+kernel/net/ipv4/netfilter/nf_defrag_ipv4.ko.gz:
+kernel/net/ipv6/netfilter/nf_defrag_ipv6.ko.gz: kernel/net/ipv6/ipv6.ko.gz
+kernel/net/netfilter/nf_conntrack.ko.gz: kernel/net/ipv4/netfilter/nf_defrag_ipv4.ko.gz kernel/net/ipv6/netfilter/nf_defrag_ipv6.ko.gz
+kernel/net/netfilter/nf_nat.ko.gz: kernel/net/netfilter/nf_conntrack.ko.gz
+kernel/net/netfilter/nf_conntrack_netlink.ko.gz: kernel/net/netfilter/nf_conntrack.ko.gz
+kernel/net/netfilter/nf_tables.ko.gz: kernel/net/netfilter/nf_conntrack.ko.gz
+kernel/net/netfilter/nft_compat.ko.gz: kernel/net/netfilter/nf_tables.ko.gz
+kernel/net/netfilter/nft_chain_nat.ko.gz: kernel/net/netfilter/nf_tables.ko.gz kernel/net/netfilter/nf_nat.ko.gz
+kernel/net/netfilter/nft_ct.ko.gz: kernel/net/netfilter/nf_tables.ko.gz kernel/net/netfilter/nf_conntrack.ko.gz
+kernel/net/netfilter/nft_masq.ko.gz: kernel/net/netfilter/nf_tables.ko.gz kernel/net/netfilter/nf_nat.ko.gz kernel/net/netfilter/nf_conntrack.ko.gz
+kernel/net/netfilter/nft_nat.ko.gz: kernel/net/netfilter/nf_tables.ko.gz kernel/net/netfilter/nf_nat.ko.gz
+kernel/net/netfilter/nft_redir.ko.gz: kernel/net/netfilter/nf_tables.ko.gz kernel/net/netfilter/nf_nat.ko.gz
+kernel/net/netfilter/xt_conntrack.ko.gz: kernel/net/netfilter/nf_conntrack.ko.gz
+kernel/net/netfilter/xt_MASQUERADE.ko.gz: kernel/net/netfilter/nf_nat.ko.gz kernel/net/netfilter/nf_conntrack.ko.gz
+kernel/net/netfilter/xt_mark.ko.gz:
+kernel/net/netfilter/xt_comment.ko.gz:
+kernel/net/netfilter/xt_multiport.ko.gz:
+kernel/net/netfilter/xt_nat.ko.gz: kernel/net/netfilter/nf_nat.ko.gz
+kernel/net/netfilter/xt_addrtype.ko.gz:
+kernel/net/netfilter/xt_connmark.ko.gz: kernel/net/netfilter/nf_conntrack.ko.gz
+kernel/net/netfilter/xt_REDIRECT.ko.gz: kernel/net/netfilter/nf_nat.ko.gz
+kernel/net/netfilter/xt_recent.ko.gz:
+kernel/net/netfilter/xt_statistic.ko.gz:
+kernel/net/netfilter/xt_set.ko.gz: kernel/net/netfilter/ipset/ip_set.ko.gz
+kernel/net/netfilter/ipset/ip_set.ko.gz:
+kernel/net/ipv4/netfilter/nf_reject_ipv4.ko.gz:
+kernel/net/ipv6/netfilter/nf_reject_ipv6.ko.gz:
+kernel/net/ipv4/netfilter/ipt_REJECT.ko.gz: kernel/net/ipv4/netfilter/nf_reject_ipv4.ko.gz
+kernel/net/ipv6/netfilter/ip6t_REJECT.ko.gz: kernel/net/ipv6/netfilter/nf_reject_ipv6.ko.gz
+kernel/net/netfilter/nft_reject.ko.gz: kernel/net/netfilter/nf_tables.ko.gz
+kernel/net/bridge/bridge.ko.gz: kernel/net/802/stp.ko.gz kernel/net/llc/llc.ko.gz
+kernel/net/bridge/br_netfilter.ko.gz: kernel/net/bridge/bridge.ko.gz kernel/net/802/stp.ko.gz kernel/net/llc/llc.ko.gz
+kernel/net/bridge/netfilter/nf_conntrack_bridge.ko.gz: kernel/net/netfilter/nf_conntrack.ko.gz kernel/net/bridge/bridge.ko.gz
+MODDEP
+
+            find "$ROOTFS_MOD_DST" -name '*.ko.gz' -path '*/net/*' | sort | while IFS= read -r mod_file; do
+                rel_path="kernel/${mod_file#$ROOTFS_MOD_DST/}"
+                if ! grep -q "^${rel_path}:" "$MODULES_DEP" 2>/dev/null; then
+                    echo "${rel_path}:" >> "$MODULES_DEP"
+                fi
+            done
+            echo "    Updated modules.dep with netfilter entries"
+        fi
+    fi
+fi
+
+# Install iptables-nft (nftables-based iptables) from the builder system
+# Kernel 6.18 uses nf_tables, not legacy ip_tables, so we need xtables-nft-multi
+echo "    Installing iptables-nft from builder..."
+if [ -f /usr/sbin/xtables-nft-multi ]; then
+    mkdir -p "$ROOTFS/usr/sbin"
+    cp /usr/sbin/xtables-nft-multi "$ROOTFS/usr/sbin/"
+
+    # Create standard symlinks
+    for cmd in iptables iptables-save iptables-restore ip6tables ip6tables-save ip6tables-restore; do
+        ln -sf xtables-nft-multi "$ROOTFS/usr/sbin/$cmd"
+    done
+
+    # Copy required shared libraries
+    mkdir -p "$ROOTFS/usr/lib/x86_64-linux-gnu" "$ROOTFS/lib/x86_64-linux-gnu" "$ROOTFS/lib64"
+    for lib in \
+        /lib/x86_64-linux-gnu/libxtables.so.12* \
+        /lib/x86_64-linux-gnu/libmnl.so.0* \
+        /lib/x86_64-linux-gnu/libnftnl.so.11* \
+        /lib/x86_64-linux-gnu/libc.so.6 \
+        /lib64/ld-linux-x86-64.so.2; do
+        [ -e "$lib" ] && cp -aL "$lib" "$ROOTFS${lib}" 2>/dev/null || true
+    done
+
+    # Copy xtables modules directory (match extensions)
+    if [ -d /usr/lib/x86_64-linux-gnu/xtables ]; then
+        mkdir -p "$ROOTFS/usr/lib/x86_64-linux-gnu/xtables"
+        cp -a /usr/lib/x86_64-linux-gnu/xtables/*.so "$ROOTFS/usr/lib/x86_64-linux-gnu/xtables/" 2>/dev/null || true
+    fi
+
+    echo "    Installed iptables-nft (xtables-nft-multi) + shared libs"
+else
+    echo "    WARN: xtables-nft-multi not found in builder (install iptables package)"
+fi
+
+# Kernel modules list (for init to load at boot)
 cp "$PROJECT_ROOT/build/config/modules.list" "$ROOTFS/usr/lib/kubesolo-os/modules.list"
 
 # --- 4. Sysctl config ---
@@ -139,6 +369,6 @@ fi
 echo ""
 echo "==> Injection complete. Rootfs contents:"
 echo "    Total size: $(du -sh "$ROOTFS" | cut -f1)"
-echo "    KubeSolo:   $(du -h "$ROOTFS/usr/local/bin/kubesolo" | cut -f1)"
+echo "    KubeSolo:   $(du -h "$ROOTFS/usr/bin/kubesolo" | cut -f1)"
 echo "    Init stages: $(ls "$ROOTFS/usr/lib/kubesolo-os/init.d/" | wc -l)"
 echo ""
diff --git a/init/init.sh b/init/init.sh
index 5712e74..0b87de6 100755
--- a/init/init.sh
+++ b/init/init.sh
@@ -16,6 +16,39 @@
 
 set -e
 
+# --- Switch root: escape initramfs so runc pivot_root works ---
+# The kernel boots into an initramfs (rootfs), which is a special mount that
+# doesn't support pivot_root. Container runtimes (runc) need pivot_root to
+# set up container root filesystems. To fix this, we copy the rootfs to a
+# tmpfs and switch_root to it. The sentinel file prevents infinite loops.
+if [ ! -f /etc/.switched_root ]; then
+    mount -t proc proc /proc 2>/dev/null || true
+    mount -t sysfs sysfs /sys 2>/dev/null || true
+    mount -t devtmpfs devtmpfs /dev 2>/dev/null || true
+    mkdir -p /mnt/newroot
+    mount -t tmpfs -o size=400M,mode=755 tmpfs /mnt/newroot
+    echo "[init] Copying rootfs to tmpfs..." >&2
+    # Copy each top-level directory explicitly (BusyBox cp -ax on rootfs is broken)
+    for d in bin sbin usr lib lib64 etc var opt; do
+        [ -d "/$d" ] && cp -a "/$d" /mnt/newroot/ 2>/dev/null || true
+    done
+    # Recreate mount point and special directories
+    mkdir -p /mnt/newroot/proc /mnt/newroot/sys /mnt/newroot/dev
+    mkdir -p /mnt/newroot/run /mnt/newroot/tmp /mnt/newroot/mnt
+    touch /mnt/newroot/etc/.switched_root
+    mount --move /proc /mnt/newroot/proc
+    mount --move /sys /mnt/newroot/sys
+    mount --move /dev /mnt/newroot/dev
+    echo "[init] Switching root..." >&2
+    exec switch_root /mnt/newroot /sbin/init
+fi
+
+# --- PATH setup ---
+# Ensure /usr/local paths are in PATH (iptables, KubeSolo, etc.)
+export PATH="/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"
+# iptables shared libraries live in /usr/local/lib
+export LD_LIBRARY_PATH="/usr/local/lib${LD_LIBRARY_PATH:+:$LD_LIBRARY_PATH}"
+
 # --- Constants ---
 INIT_LIB="/usr/lib/kubesolo-os"
 INIT_STAGES="/usr/lib/kubesolo-os/init.d"
diff --git a/init/lib/00-early-mount.sh b/init/lib/00-early-mount.sh
index 952c8c0..3cc97b8 100755
--- a/init/lib/00-early-mount.sh
+++ b/init/lib/00-early-mount.sh
@@ -1,23 +1,62 @@
 #!/bin/sh
 # 00-early-mount.sh — Mount essential virtual filesystems
 
-mount -t proc proc /proc 2>/dev/null || true
-mount -t sysfs sysfs /sys 2>/dev/null || true
-mount -t devtmpfs devtmpfs /dev 2>/dev/null || true
-mount -t tmpfs tmpfs /tmp
-mount -t tmpfs tmpfs /run
+# After switch_root, /proc /sys /dev are already mounted — only mount if missing
+if ! mountpoint -q /proc 2>/dev/null; then
+    mount -t proc proc /proc 2>/dev/null || true
+fi
+if ! mountpoint -q /sys 2>/dev/null; then
+    mount -t sysfs sysfs /sys 2>/dev/null || true
+fi
+if ! mountpoint -q /dev 2>/dev/null; then
+    mount -t devtmpfs devtmpfs /dev 2>/dev/null || mount -t tmpfs tmpfs /dev
+fi
+if ! mountpoint -q /tmp 2>/dev/null; then
+    mount -t tmpfs tmpfs /tmp
+fi
+if ! mountpoint -q /run 2>/dev/null; then
+    mount -t tmpfs tmpfs /run
+fi
 
 mkdir -p /dev/pts /dev/shm
-mount -t devpts devpts /dev/pts
-mount -t tmpfs tmpfs /dev/shm
+if ! mountpoint -q /dev/pts 2>/dev/null; then
+    mount -t devpts devpts /dev/pts
+fi
+if ! mountpoint -q /dev/shm 2>/dev/null; then
+    mount -t tmpfs tmpfs /dev/shm
+fi
 
-# Mount cgroup2 unified hierarchy
+# Ensure essential device nodes exist (devtmpfs may be incomplete after switch_root)
+[ -e /dev/console ] || mknod -m 600 /dev/console c 5 1 2>/dev/null || true
+[ -e /dev/null ]    || mknod -m 666 /dev/null c 1 3 2>/dev/null || true
+[ -e /dev/zero ]    || mknod -m 666 /dev/zero c 1 5 2>/dev/null || true
+[ -e /dev/kmsg ]    || mknod -m 660 /dev/kmsg c 1 11 2>/dev/null || true
+[ -e /dev/random ]  || mknod -m 666 /dev/random c 1 8 2>/dev/null || true
+[ -e /dev/urandom ] || mknod -m 666 /dev/urandom c 1 9 2>/dev/null || true
+[ -e /dev/tty ]     || mknod -m 666 /dev/tty c 5 0 2>/dev/null || true
+
+# Set up BusyBox mdev as hotplug handler (creates /dev nodes for new devices)
+echo /sbin/mdev > /proc/sys/kernel/hotplug 2>/dev/null || true
+mdev -s 2>/dev/null || true
+
+# Mount cgroup v2 unified hierarchy
 mkdir -p /sys/fs/cgroup
-mount -t cgroup2 cgroup2 /sys/fs/cgroup 2>/dev/null || {
-    log_warn "cgroup v2 mount failed; attempting v1 fallback"
-    mount -t tmpfs cgroup /sys/fs/cgroup
-    for subsys in cpu cpuacct memory devices freezer pids; do
-        mkdir -p "/sys/fs/cgroup/$subsys"
-        mount -t cgroup -o "$subsys" "cgroup_${subsys}" "/sys/fs/cgroup/$subsys" 2>/dev/null || true
+if ! mountpoint -q /sys/fs/cgroup 2>/dev/null; then
+    mount -t cgroup2 cgroup2 /sys/fs/cgroup 2>/dev/null || true
+fi
+
+# Enable ALL available controllers for child cgroups
+# Required: memory (memory.max), cpu (cpu.max), pids (pids.max)
+# First, move init process to its own cgroup so controllers can be enabled
+# (cgroup v2 "no internal process" rule for non-root cgroups)
+if [ -f /sys/fs/cgroup/cgroup.controllers ]; then
+    mkdir -p /sys/fs/cgroup/init
+    echo $$ > /sys/fs/cgroup/init/cgroup.procs 2>/dev/null || true
+    for ctrl in $(cat /sys/fs/cgroup/cgroup.controllers); do
+        echo "+${ctrl}" > /sys/fs/cgroup/cgroup.subtree_control 2>/dev/null || true
     done
-}
+fi
+
+# Mount BPF filesystem (required for cgroup v2 device control via BPF)
+mkdir -p /sys/fs/bpf
+mount -t bpf bpf /sys/fs/bpf 2>/dev/null || true
diff --git a/init/lib/20-persistent-mount.sh b/init/lib/20-persistent-mount.sh
index 30fc662..415c424 100755
--- a/init/lib/20-persistent-mount.sh
+++ b/init/lib/20-persistent-mount.sh
@@ -8,11 +8,26 @@ if [ "$KUBESOLO_NOPERSIST" = "1" ]; then
     return 0
 fi
 
+# Load block device drivers before waiting (modules loaded later in stage 30,
+# but we need virtio_blk available NOW for /dev/vda detection)
+modprobe virtio_blk 2>/dev/null || true
+# Trigger mdev to create device nodes after loading driver
+mdev -s 2>/dev/null || true
+
+# Fallback: create device node from sysfs if devtmpfs/mdev didn't
+DEV_NAME="${KUBESOLO_DATA_DEV##*/}"
+if [ ! -b "$KUBESOLO_DATA_DEV" ] && [ -f "/sys/class/block/$DEV_NAME/dev" ]; then
+    MAJMIN=$(cat "/sys/class/block/$DEV_NAME/dev")
+    mknod "$KUBESOLO_DATA_DEV" b "${MAJMIN%%:*}" "${MAJMIN##*:}" 2>/dev/null || true
+    log "Created $KUBESOLO_DATA_DEV via mknod ($MAJMIN)"
+fi
+
 # Wait for device to appear (USB, slow disks, virtio)
 log "Waiting for data device: $KUBESOLO_DATA_DEV"
 WAIT_SECS=30
 for i in $(seq 1 "$WAIT_SECS"); do
     [ -b "$KUBESOLO_DATA_DEV" ] && break
+    mdev -s 2>/dev/null || true
     sleep 1
 done
 
diff --git a/init/lib/50-network.sh b/init/lib/50-network.sh
index 918f940..fcdf2be 100755
--- a/init/lib/50-network.sh
+++ b/init/lib/50-network.sh
@@ -18,16 +18,16 @@ fi
 # Fallback: DHCP on first non-loopback interface
 log "Configuring network via DHCP"
 
-# Bring up loopback
-ip link set lo up
-ip addr add 127.0.0.1/8 dev lo
+# Bring up loopback (use ifconfig for BusyBox compatibility)
+ifconfig lo 127.0.0.1 netmask 255.0.0.0 up 2>/dev/null || \
+    { ip link set lo up 2>/dev/null && ip addr add 127.0.0.1/8 dev lo 2>/dev/null; } || true
 
 # Find first ethernet interface
 ETH_DEV=""
 for iface in /sys/class/net/*; do
     iface="$(basename "$iface")"
     case "$iface" in
-        lo|docker*|veth*|br*|cni*) continue ;;
+        lo|docker*|veth*|br*|cni*|dummy*|tunl*|sit*) continue ;;
     esac
     ETH_DEV="$iface"
     break
@@ -39,7 +39,7 @@ if [ -z "$ETH_DEV" ]; then
 fi
 
 log "Using interface: $ETH_DEV"
-ip link set "$ETH_DEV" up
+ifconfig "$ETH_DEV" up 2>/dev/null || ip link set "$ETH_DEV" up 2>/dev/null || true
 
 # Run DHCP client (BusyBox udhcpc)
 if command -v udhcpc >/dev/null 2>&1; then
diff --git a/init/lib/60-hostname.sh b/init/lib/60-hostname.sh
index 9331813..cbc9f5d 100755
--- a/init/lib/60-hostname.sh
+++ b/init/lib/60-hostname.sh
@@ -31,4 +31,17 @@ hostname "$HOSTNAME"
 echo "$HOSTNAME" > /etc/hostname
 echo "127.0.0.1 $HOSTNAME" >> /etc/hosts
 
+# Generate /etc/machine-id if missing (kubelet requires it)
+if [ ! -f /etc/machine-id ]; then
+    if [ -f "$DATA_MOUNT/etc-kubesolo/machine-id" ]; then
+        cp "$DATA_MOUNT/etc-kubesolo/machine-id" /etc/machine-id
+    else
+        # Generate from hostname hash (deterministic across reboots)
+        printf '%s' "$HOSTNAME" | md5sum 2>/dev/null | cut -d' ' -f1 > /etc/machine-id || \
+            cat /proc/sys/kernel/random/uuid 2>/dev/null | tr -d '-' > /etc/machine-id || true
+        # Persist for next boot
+        cp /etc/machine-id "$DATA_MOUNT/etc-kubesolo/machine-id" 2>/dev/null || true
+    fi
+fi
+
 log_ok "Hostname set to: $HOSTNAME"
diff --git a/init/lib/90-kubesolo.sh b/init/lib/90-kubesolo.sh
index 9cd496a..840d5d3 100755
--- a/init/lib/90-kubesolo.sh
+++ b/init/lib/90-kubesolo.sh
@@ -4,7 +4,7 @@
 # This stage exec's KubeSolo as PID 1 (replacing init).
 # KubeSolo manages containerd, kubelet, API server, and all K8s components.
 
-KUBESOLO_BIN="/usr/local/bin/kubesolo"
+KUBESOLO_BIN="/usr/bin/kubesolo"
 
 if [ ! -x "$KUBESOLO_BIN" ]; then
     log_err "KubeSolo binary not found at $KUBESOLO_BIN"
@@ -12,7 +12,7 @@ if [ ! -x "$KUBESOLO_BIN" ]; then
 fi
 
 # Build KubeSolo command line
-KUBESOLO_ARGS="--path /var/lib/kubesolo --local-storage true"
+KUBESOLO_ARGS="--path /var/lib/kubesolo --local-storage"
 
 # Add extra SANs if hostname resolves
 HOSTNAME="$(hostname)"
@@ -30,6 +30,17 @@ if [ -f /etc/kubesolo/extra-flags ]; then
     KUBESOLO_ARGS="$KUBESOLO_ARGS $(cat /etc/kubesolo/extra-flags)"
 fi
 
+# Pre-initialize iptables filter table and base chains.
+# KubeSolo's kube-proxy uses iptables-restore (nf_tables backend) which needs
+# the filter table to exist. Without this, the first iptables-restore fails
+# with "RULE_APPEND failed (No such file or directory)".
+if command -v iptables >/dev/null 2>&1; then
+    iptables -t filter -L -n >/dev/null 2>&1 || true
+    iptables -t nat -L -n >/dev/null 2>&1 || true
+    iptables -t mangle -L -n >/dev/null 2>&1 || true
+    log "Pre-initialized iptables tables (filter, nat, mangle)"
+fi
+
 log "Starting KubeSolo: $KUBESOLO_BIN $KUBESOLO_ARGS"
 log "Kubeconfig will be at: /var/lib/kubesolo/pki/admin/admin.kubeconfig"
 
diff --git a/init/lib/functions.sh b/init/lib/functions.sh
index 1e0f8ea..0796cc9 100755
--- a/init/lib/functions.sh
+++ b/init/lib/functions.sh
@@ -29,11 +29,16 @@ wait_for_file() {
     return 1
 }
 
-# Get IP address of an interface (POSIX-safe, no grep -P)
+# Get IP address of an interface (BusyBox-safe: prefer ifconfig, fall back to ip)
 get_iface_ip() {
     iface="$1"
-    ip -4 addr show "$iface" 2>/dev/null | \
-        sed -n 's/.*inet \([0-9.]*\).*/\1/p' | head -1
+    if command -v ifconfig >/dev/null 2>&1; then
+        ifconfig "$iface" 2>/dev/null | \
+            sed -n 's/.*inet addr:\([0-9.]*\).*/\1/p;s/.*inet \([0-9.]*\).*/\1/p' | head -1
+    elif command -v ip >/dev/null 2>&1; then
+        ip -4 addr show "$iface" 2>/dev/null | \
+            sed -n 's/.*inet \([0-9.]*\).*/\1/p' | head -1
+    fi
 }
 
 # Check if running in a VM (useful for adjusting timeouts)