diff --git a/guests/linux-aarch64/initramfs.img b/guests/linux-aarch64/initramfs.img
new file mode 100644
index 000000000..8def86add
Binary files /dev/null and b/guests/linux-aarch64/initramfs.img differ
diff --git a/guests/linux-aarch64/initramfs/build.sh b/guests/linux-aarch64/initramfs/build.sh
new file mode 100644
index 000000000..a3287661d
--- /dev/null
+++ b/guests/linux-aarch64/initramfs/build.sh
@@ -0,0 +1,62 @@
+#!/bin/bash
+# Build a minimal initramfs for UniversalisOS Linux guest.
+# Cross-compiles init.c for AArch64 and creates a cpio archive.
+
+set -e
+
+SCRIPT_DIR="$(cd "$(dirname "$0")" && pwd)"
+OUTPUT_DIR="$SCRIPT_DIR/.."
+INITRAMFS_DIR="$SCRIPT_DIR/rootfs"
+
+# Cross-compiler
+CROSS=aarch64-linux-gnu
+CC=${CROSS}-gcc
+OBJCOPY=${CROSS}-objcopy
+STRIP=${CROSS}-strip
+
+echo "=== Building minimal initramfs ==="
+
+# Create rootfs directory structure
+rm -rf "$INITRAMFS_DIR"
+mkdir -p "$INITRAMFS_DIR"/{bin,dev,proc,sys,etc,sbin}
+
+# Compile init.c as static binary
+echo "Compiling init.c..."
+${CC} -static -O2 -o "$INITRAMFS_DIR/init" "$SCRIPT_DIR/init.c"
+${STRIP} "$INITRAMFS_DIR/init"
+echo "init binary: $(file "$INITRAMFS_DIR/init")"
+
+# Create a minimal /etc/init.d/rcS
+cat > "$INITRAMFS_DIR/etc/init.d/rcS" << 'EOF'
+#!/bin/sh
+echo "Running rcS..."
+mount -t proc proc /proc
+mount -t sysfs sysfs /sys
+mount -t tmpfs tmpfs /dev
+exec /init
+EOF
+chmod +x "$INITRAMFS_DIR/etc/init.d/rcS"
+
+# Create a minimal /etc/fstab
+cat > "$INITRAMFS_DIR/etc/fstab" << 'EOF'
+# <filesystem>  <mount point>  <type>  <options>  <dump>  <pass>
+proc            /proc          proc    defaults   0       0
+sysfs           /sys           sysfs   defaults   0       0
+tmpfs           /dev           tmpfs   defaults   0       0
+EOF
+
+# Create cpio archive
+echo "Creating cpio archive..."
+cd "$INITRAMFS_DIR"
+find . -print0 | cpio --null -o --format=newc > "$OUTPUT_DIR/initramfs.cpio"
+cd "$SCRIPT_DIR"
+
+# Create gzip-compressed version
+echo "Compressing..."
+gzip -9 -f "$OUTPUT_DIR/initramfs.cpio"
+mv "$OUTPUT_DIR/initramfs.cpio.gz" "$OUTPUT_DIR/initramfs.img"
+
+echo "=== Initramfs built ==="
+echo "Output: $OUTPUT_DIR/initramfs.img"
+echo "Size: $(du -h "$OUTPUT_DIR/initramfs.img" | cut -f1)"
+ls -la "$OUTPUT_DIR/initramfs.img"
diff --git a/guests/linux-aarch64/initramfs/init.c b/guests/linux-aarch64/initramfs/init.c
new file mode 100644
index 000000000..23268bff2
--- /dev/null
+++ b/guests/linux-aarch64/initramfs/init.c
@@ -0,0 +1,144 @@
+/*
+ * Minimal /init for UniversalisOS initramfs.
+ *
+ * This is the first userspace program executed by Linux after mounting
+ * the rootfs. It demonstrates that the hypervisor can boot a real Linux
+ * kernel to userspace via virtio-blk.
+ *
+ * Features:
+ *   - Mounts /proc, /sys, /dev (tmpfs)
+ *   - Prints system information from /proc/cpuinfo
+ *   - Runs a minimal shell loop (echo + wait)
+ *   - Demonstrates the full hypervisor -> Linux -> userspace path
+ */
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <unistd.h>
+#include <sys/mount.h>
+#include <sys/stat.h>
+#include <sys/sysmacros.h>
+#include <sys/reboot.h>
+#include <linux/reboot.h>
+
+#define BANNER \
+    "\r\n" \
+    "============================================\r\n" \
+    " UniversalisOS Linux Guest Boot Successful!\r\n" \
+    "============================================\r\n" \
+    "\r\n"
+
+static void mount_proc(void) {
+    mkdir("/proc", 0755);
+    if (mount("proc", "/proc", "proc", 0, NULL) == 0) {
+        printf("[init] /proc mounted\r\n");
+    } else {
+        printf("[init] /proc mount failed\r\n");
+    }
+}
+
+static void mount_sys(void) {
+    mkdir("/sys", 0755);
+    if (mount("sysfs", "/sys", "sysfs", 0, NULL) == 0) {
+        printf("[init] /sys mounted\r\n");
+    } else {
+        printf("[init] /sys mount failed\r\n");
+    }
+}
+
+static void mount_dev(void) {
+    mkdir("/dev", 0755);
+    if (mount("tmpfs", "/dev", "tmpfs", 0, "size=64M") == 0) {
+        printf("[init] /dev mounted (tmpfs)\r\n");
+    } else {
+        printf("[init] /dev mount failed\r\n");
+    }
+}
+
+static void print_cpuinfo(void) {
+    FILE *f = fopen("/proc/cpuinfo", "r");
+    if (f) {
+        char line[256];
+        printf("[init] CPU info:\r\n");
+        while (fgets(line, sizeof(line), f)) {
+            if (strncmp(line, "Processor", 9) == 0 ||
+                strncmp(line, "model name", 10) == 0 ||
+                strncmp(line, "CPU implementer", 14) == 0 ||
+                strncmp(line, "CPU variant", 10) == 0 ||
+                strncmp(line, "BogoMIPS", 8) == 0) {
+                printf("  %s", line);
+            }
+        }
+        fclose(f);
+    }
+}
+
+static void print_uptime(void) {
+    FILE *f = fopen("/proc/uptime", "r");
+    if (f) {
+        double uptime;
+        if (fscanf(f, "%lf", &uptime) == 1) {
+            printf("[init] System uptime: %.1f seconds\r\n", uptime);
+        }
+        fclose(f);
+    }
+}
+
+static void print_memory(void) {
+    FILE *f = fopen("/proc/meminfo", "r");
+    if (f) {
+        char line[256];
+        printf("[init] Memory info:\r\n");
+        while (fgets(line, sizeof(line), f)) {
+            if (strncmp(line, "MemTotal", 8) == 0 ||
+                strncmp(line, "MemFree", 7) == 0 ||
+                strncmp(line, "MemAvailable", 12) == 0) {
+                printf("  %s", line);
+            }
+        }
+        fclose(f);
+    }
+}
+
+int main(void) {
+    printf(BANNER);
+    printf("[init] UniversalisOS Linux Guest Init\r\n");
+    printf("[init] PID=%d\r\n", getpid());
+
+    /* Mount essential filesystems */
+    mount_dev();
+    mount_proc();
+    mount_sys();
+
+    /* Create basic device nodes */
+    mknod("/dev/console", 0600 | S_IFCHR, makedev(5, 1));
+    mknod("/dev/null", 0666 | S_IFCHR, makedev(1, 3));
+    mknod("/dev/zero", 0666 | S_IFCHR, makedev(1, 5));
+
+    /* Print system information */
+    print_cpuinfo();
+    print_uptime();
+    print_memory();
+
+    /* Print mount info */
+    FILE *f = fopen("/proc/mounts", "r");
+    if (f) {
+        char line[256];
+        printf("[init] Mounts:\r\n");
+        while (fgets(line, sizeof(line), f)) {
+            printf("  %s", line);
+        }
+        fclose(f);
+    }
+
+    printf("\r\n[init] System ready. Entering idle loop.\r\n");
+    printf("[init] To shutdown: echo 1 > /proc/sys/kernel/sysrq && echo o > /proc/sysrq-trigger\r\n");
+
+    /* Idle loop — in a real system this would run a shell or service manager */
+    while (1) {
+        sleep(10);
+        printf("[init] heartbeat\r\n");
+    }
+
+    return 0;
+}
diff --git a/guests/linux-aarch64/initramfs/rootfs/init b/guests/linux-aarch64/initramfs/rootfs/init
new file mode 100755
index 000000000..e7850d596
Binary files /dev/null and b/guests/linux-aarch64/initramfs/rootfs/init differ
diff --git a/guests/linux-aarch64/mkdisk.py b/guests/linux-aarch64/mkdisk.py
new file mode 100644
index 000000000..3940c2e2d
--- /dev/null
+++ b/guests/linux-aarch64/mkdisk.py
@@ -0,0 +1,80 @@
+#!/usr/bin/env python3
+"""
+Generate a virtio-blk disk image for UniversalisOS Linux guest.
+
+Creates a raw disk image with the UOSVBLK1 header format that
+virtio-blk can detect and serve to the guest.
+
+Usage:
+    python3 mkdisk.py <input_file> <output.img> [--size=SIZE]
+
+The output image format:
+    Offset 0x000: "UOSVBLK1" magic (8 bytes)
+    Offset 0x008: data size in bytes (8 bytes, little-endian)
+    Offset 0x010: raw sector data (512-byte aligned)
+"""
+import sys
+import os
+import struct
+
+MAGIC = b"UOSVBLK1"
+SECTOR_SIZE = 512
+
+def create_disk_image(input_path, output_path, target_size=None):
+    """Create a virtio-blk disk image from an input file."""
+    
+    # Read input file
+    with open(input_path, 'rb') as f:
+        data = f.read()
+    
+    # Pad to sector boundary
+    if len(data) % SECTOR_SIZE != 0:
+        data += b'\x00' * (SECTOR_SIZE - (len(data) % SECTOR_SIZE))
+    
+    # Pad to target size if specified
+    if target_size and target_size > len(data):
+        data += b'\x00' * (target_size - len(data))
+    
+    # Create image with header
+    header = MAGIC + struct.pack('<Q', len(data))  # magic + size (LE 64-bit)
+    
+    # Pad header to sector boundary
+    if len(header) % SECTOR_SIZE != 0:
+        header += b'\x00' * (SECTOR_SIZE - len(header))
+    
+    image = header + data
+    
+    # Write output
+    with open(output_path, 'wb') as f:
+        f.write(image)
+    
+    print(f"Disk image created: {output_path}")
+    print(f"  Input: {input_path} ({len(data)} bytes)")
+    print(f"  Header: {len(header)} bytes")
+    print(f"  Total: {len(image)} bytes ({len(image) // 1024} KB)")
+    print(f"  Sectors: {len(image) // SECTOR_SIZE}")
+
+def main():
+    if len(sys.argv) < 3:
+        print(f"Usage: {sys.argv[0]} <input> <output.img> [--size=SIZE]")
+        print(f"  input:     input file (initramfs, rootfs, etc.)")
+        print(f"  output:    output disk image")
+        print(f"  --size:    target size in bytes (optional, pads with zeros)")
+        sys.exit(1)
+    
+    input_path = sys.argv[1]
+    output_path = sys.argv[2]
+    target_size = None
+    
+    for arg in sys.argv[3:]:
+        if arg.startswith('--size='):
+            target_size = int(arg.split('=')[1])
+    
+    if not os.path.exists(input_path):
+        print(f"Error: input file not found: {input_path}")
+        sys.exit(1)
+    
+    create_disk_image(input_path, output_path, target_size)
+
+if __name__ == '__main__':
+    main()
diff --git a/guests/linux-aarch64/rootfs.img b/guests/linux-aarch64/rootfs.img
new file mode 100644
index 000000000..39b690558
Binary files /dev/null and b/guests/linux-aarch64/rootfs.img differ
diff --git a/guests/linux-aarch64/rootfs/Makefile b/guests/linux-aarch64/rootfs/Makefile
new file mode 100644
index 000000000..da479e8ba
--- /dev/null
+++ b/guests/linux-aarch64/rootfs/Makefile
@@ -0,0 +1,140 @@
+# UniversalisOS Linux Guest Rootfs Generation
+#
+# Targets:
+#   make minimal   - Build minimal initramfs (init only, ~50KB)
+#   make busybox   - Build busybox-based initramfs (~1MB)
+#   make full      - Build full rootfs from yocto/buildroot (~50MB)
+#   make disk      - Create virtio-blk disk image
+#   make all       - Build minimal + disk image
+#   make clean     - Remove all build artifacts
+#
+# Prerequisites:
+#   - aarch64-linux-gnu-gcc (cross-compiler)
+#   - cpio, gzip (for initramfs)
+#   - python3 (for mkdisk.py)
+
+# Configuration
+CROSS_COMPILE ?= aarch64-linux-gnu-
+CC = $(CROSS_COMPILE)gcc
+STRIP = $(CROSS_COMPILE)strip
+
+# Directories
+ROOTFS_DIR = $(CURDIR)
+OUTPUT_DIR = $(ROOTFS_DIR)/output
+BUILD_DIR = $(ROOTFS_DIR)/build
+INITRAMFS_DIR = $(BUILD_DIR)/initramfs
+
+# Output files
+INITRAMFS_IMG = $(OUTPUT_DIR)/initramfs.img
+DISK_IMG = $(OUTPUT_DIR)/rootfs.img
+
+# Disk image size (256 MiB for full rootfs)
+DISK_SIZE = 268435456
+
+# Busybox configuration
+BUSYBOX_VERSION = 1.36.1
+BUSYBOX_URL = https://busybox.net/downloads/busybox-$(BUSYBOX_VERSION).tar.bz2
+
+# ===== Minimal initramfs (init only) =====
+
+.PHONY: minimal
+minimal: $(INITRAMFS_IMG)
+
+$(OUTPUT_DIR):
+	mkdir -p $(OUTPUT_DIR)
+
+$(BUILD_DIR):
+	mkdir -p $(BUILD_DIR)
+
+$(INITRAMFS_DIR): $(BUILD_DIR)
+	mkdir -p $(INITRAMFS_DIR)/{bin,dev,proc,sys,etc,sbin}
+
+$(INITRAMFS_DIR)/init: $(INITRAMFS_DIR) $(ROOTFS_DIR)/initramfs/init.c
+	$(CC) -static -O2 -o $@ $(ROOTFS_DIR)/initramfs/init.c
+	$(STRIP) $@
+
+$(INITRAMFS_DIR)/etc/init.d/rcS: $(INITRAMFS_DIR)
+	mkdir -p $(INITRAMFS_DIR)/etc/init.d
+	@echo '#!/bin/sh' > $@
+	@echo 'mount -t proc proc /proc' >> $@
+	@echo 'mount -t sysfs sysfs /sys' >> $@
+	@echo 'mount -t tmpfs tmpfs /dev' >> $@
+	@chmod +x $@
+
+$(INITRAMFS_DIR)/etc/fstab: $(INITRAMFS_DIR)
+	@echo '# <filesystem>  <mount>  <type>  <opts>  <dump>  <pass>' > $@
+	@echo 'proc            /proc    proc    defaults   0       0' >> $@
+	@echo 'sysfs           /sys     sysfs   defaults   0       0' >> $@
+	@echo 'tmpfs           /dev     tmpfs   defaults   0       0' >> $@
+
+$(INITRAMFS_IMG): $(INITRAMFS_DIR)/init $(INITRAMFS_DIR)/etc/init.d/rcS $(INITRAMFS_DIR)/etc/fstab
+	cd $(INITRAMFS_DIR) && find . -print0 | cpio --null -o --format=newc 2>/dev/null | gzip -9 > $@
+	@echo "Initramfs: $$(du -h $@ | cut -f1)"
+
+# ===== Busybox initramfs =====
+
+.PHONY: busybox
+busybox: $(OUTPUT_DIR)/busybox-initramfs.img
+
+$(BUILD_DIR)/busybox-$(BUSYBOX_VERSION): $(BUILD_DIR)
+	cd $(BUILD_DIR) && curl -L $(BUSYBOX_URL) | tar xj
+	cd $(BUILD_DIR)/busybox-$(BUSYBOX_VERSION) && make ARCH=aarch64 CROSS_COMPILE=$(CROSS_COMPILE) defconfig
+	cd $(BUILD_DIR)/busybox-$(BUSYBOX_VERSION) && sed -i 's/# CONFIG_STATIC is not set/CONFIG_STATIC=y/' .config
+	cd $(BUILD_DIR)/busybox-$(BUSYBOX_VERSION) && make ARCH=aarch64 CROSS_COMPILE=$(CROSS_COMPILE) -j$$(nproc)
+
+$(BUILD_DIR)/busybox-rootfs: $(BUILD_DIR)/busybox-$(BUSYBOX_VERSION)
+	mkdir -p $@/{bin,dev,proc,sys,etc,sbin,tmp,root}
+	cp $(BUILD_DIR)/busybox-$(BUSYBOX_VERSION)/busybox $@/bin/busybox
+	cd $@/bin && for cmd in sh ls cat echo mount mkdir mknod sleep reboot; do ln -sf busybox $$cmd; done
+	cd $@/sbin && ln -sf ../bin/busybox init
+	@echo '#!/bin/sh' > $@/etc/init.d/rcS
+	@echo 'mount -t proc proc /proc' >> $@/etc/init.d/rcS
+	@echo 'mount -t sysfs sysfs /sys' >> $@/etc/init.d/rcS
+	@echo 'mount -t tmpfs tmpfs /dev' >> $@/etc/init.d/rcS
+	@echo 'mount -t devpts devpts /dev/pts' >> $@/etc/init.d/rcS
+	@chmod +x $@/etc/init.d/rcS
+
+$(OUTPUT_DIR)/busybox-initramfs.img: $(BUILD_DIR)/busybox-rootfs $(OUTPUT_DIR)
+	cd $(BUILD_DIR)/busybox-rootfs && find . -print0 | cpio --null -o --format=newc 2>/dev/null | gzip -9 > $@
+	@echo "Busybox initramfs: $$(du -h $@ | cut -f1)"
+
+# ===== Full rootfs (yocto/buildroot placeholder) =====
+
+.PHONY: full
+full: $(OUTPUT_DIR)/full-rootfs.img
+
+$(OUTPUT_DIR)/full-rootfs.img: $(OUTPUT_DIR)
+	@echo "=== Full rootfs generation ==="
+	@echo "This target requires yocto or buildroot to be configured."
+	@echo "To use:"
+	@echo "  1. Configure yocto/buildroot for aarch64"
+	@echo "  2. Build the rootfs"
+	@echo "  3. Copy the output to $(OUTPUT_DIR)/full-rootfs/"
+	@echo "  4. Run: make disk INPUT=$(OUTPUT_DIR)/full-rootfs/"
+	@echo ""
+	@echo "For now, using minimal initramfs as fallback."
+	$(MAKE) minimal
+	cp $(INITRAMFS_IMG) $@
+
+# ===== Disk image generation =====
+
+.PHONY: disk
+disk: $(DISK_IMG)
+
+$(DISK_IMG): $(INITRAMFS_IMG)
+	python3 ../mkdisk.py $(INITRAMFS_IMG) $@ --size=$(DISK_SIZE)
+	@echo "Disk image: $$(du -h $@ | cut -f1)"
+
+# ===== All =====
+
+.PHONY: all
+all: minimal disk
+	@echo "=== Build complete ==="
+	@echo "Initramfs: $(INITRAMFS_IMG)"
+	@echo "Disk image: $(DISK_IMG)"
+
+# ===== Clean =====
+
+.PHONY: clean
+clean:
+	rm -rf $(BUILD_DIR) $(OUTPUT_DIR)