Creating Bootable Media and Installation

Understanding ISO Creation

After building PanOS, you have initramfs.cpio and vmlinuz. To make it bootable on physical hardware, you need a bootable ISO file.

What is ISO 9660?

ISO 9660 is a filesystem standard for optical media (DVDs/CDs) and USB drives. It includes:

• Kernel file (vmlinuz)
• Initramfs (initramfs.cpio)
• Bootloader (GRUB)
• Bootloader config (grub.cfg)

Creating the ISO

Quick Method

./4-create-iso.sh

This creates pan-os-booteable.iso (~156 MB) in ~/pan-os-iso/build/.

What the Script Does

[1/3] Preparing estructura...
  Creating grub-iso/ directory
  Copying kernel and initramfs

[2/3] Configurando GRUB...
  Creating grub.cfg
  GRUB configuration ready

[3/3] Generating ISO...
  Running grub-mkrescue...
  
✅ ISO Booteable creada successfully

Verify ISO Creation

# Check the ISO file exists
ls -lh ~/pan-os-iso/build/pan-os-booteable.iso
# Output: -rw-r--r-- 1 user user 156M Feb 16 12:00 pan-os-booteable.iso

# Verify it's a valid ISO
file ~/pan-os-iso/build/pan-os-booteable.iso
# Output: ISO 9660 CD-ROM filesystem data...

Booting ISO in QEMU

The easiest way to test the ISO:

qemu-system-x86_64 \
    -cdrom ~/pan-os-iso/build/pan-os-booteable.iso \
    -m 2048 \
    -smp 2 \
    -nographic \
    -serial stdio

Output sequence:

1. QEMU starts
2. BIOS/UEFI loads
3. GRUB menu appears (or auto-boots)
4. Kernel loads from ISO
5. Initramfs loads
6. PanOS shell prompt appears

This validates the ISO is bootable.

Creating Bootable USB Drive

Preparation

Step 1: Get USB drive information

# Connect USB drive to computer
# WARNING: This will ERASE the USB drive!

# List storage devices
lsblk

# Output example:
# sda      8:0    0  500G  0 disk
# ├─sda1   8:1    0  100M  0 part /boot
# └─sda2   8:2    0  400G  0 part /
# sdb      8:16   0   16G  0 disk  ← USB Drive
# └─sdb1   8:17   0   16G  0 part /media/usb

# Identify USB: /dev/sdb (NOT /dev/sdb1!)

Step 2: Unmount USB if mounted

sudo umount /media/usb
# Or
sudo umount /dev/sdb1

Writing ISO to USB

DANGER: Ensure you have the correct device (/dev/sdX not /dev/sdX1).

# Use dd command to write ISO to USB
sudo dd if=~/pan-os-iso/build/pan-os-booteable.iso \
         of=/dev/sdb \
         bs=4M \
         status=progress
         
# Progress output:
# 156M bytes (156M) copied, 45.2 s, 3.4 MB/s

Parameters explained:

• if=: Input file (ISO)
• of=: Output device (USB drive - use /dev/sdX not /dev/sdX1)
• bs=4M: Block size (larger = faster, but must fit in RAM)
• status=progress: Show progress

Expected output:

156+0 records in
156+0 records out
163577856 bytes (164 MB) copied, 45.234 s, 3.4 MB/s

Verify USB Write

After writing completes:

# Verify checksum (optional but recommended)
sha256sum ~/pan-os-iso/build/pan-os-booteable.iso
sudo md5sum /dev/sdb | head -c 32

# Eject safe
sudo eject /dev/sdb

Booting from USB

On Physical Computer

1. Insert USB into computer

2. Turn on computer

3. Press boot menu key during startup:

   • Dell: F12
   • HP: ESC
   • Lenovo: F12
   • ASUS: DEL or F2
   • Generic: ESC, F1, F2, F10, F12

4. Select USB drive from boot menu

5. PanOS boots from USB

On Virtual Machine

VirtualBox

1. Open VirtualBox

2. Create new VM:

   VBoxManage createvm --name PanOS --ostype Linux_64 \
      --register

3. Add virtual hard disk:

   VBoxManage createhd --filename PanOS.vdi --size 4096
   VBoxManage storagectl PanOS --name SATA --add sata
   VBoxManage storageattach PanOS --storagectl SATA \
      --port 0 --device 0 --type hdd --medium PanOS.vdi

4. Attach ISO:

   VBoxManage storagectl PanOS --name IDE --add ide
   VBoxManage storageattach PanOS --storagectl IDE \
      --port 0 --device 0 --type dvddrive \
      --medium ~/pan-os-iso/build/pan-os-booteable.iso

5. Boot VM:

   VBoxHeadless -startvm PanOS

OR use VirtualBox GUI: Settings → Storage → attach ISO → boot

VMware

1. Open VMware
2. Create new VM with Linux/Other settings
3. Attach ISO: VM Settings → CD/DVD → connect ISO
4. Boot and PanOS loads

Hyper-V

1. Open Hyper-V Manager
2. New Virtual Machine → Linux configuration
3. Attach ISO: Generation 2 VM → Firmware → DVD
4. Boot

Network Boot (PXE)

For server deployments, boot PanOS over network:

Setup PXE Server

Required on your network:

# DHCP server (provides IP)
# TFTP server (downloads vmlinuz)
# HTTP server (downloads initramfs)

# Example: minimal DHCP/TFTP config
# /etc/dnsmasq.conf
dhcp-range=192.168.1.50,192.168.1.150
pxe-service=x86PC,"PanOS",pxelinux.0
tftp-root=/srv/tftp

Boot PanOS via PXE

Computer with PXE-capable NIC:

1. Enable PXE in BIOS settings
2. Boot - pulls vmlinuz and initramfs over network
3. PanOS starts with assigned IP

Installation on Physical Hardware

Note: PanOS runs from RAM (initramfs), not persistent storage.

To Make Persistent (Advanced)

See 10-advanced.mdx for:

• Adding persistent storage
• Installing to disk
• Modifying rootfs

Current Behavior

• Boots from USB/ISO
• Loads to RAM
• Changes not saved after reboot
• Next boot loads clean system

This is ideal for:

• Live systems
• Demos
• Testing
• Embedded systems
• Diskless machines

Troubleshooting ISO Issues

Issue: ISO doesn't boot

Causes:

• Corrupted ISO
• BIOS doesn't support bootloader
• USB write failed

Solutions:

1. Verify ISO:

   file ~/pan-os-iso/build/pan-os-booteable.iso
   # Should show: ISO 9660

2. Test in QEMU first:

   qemu-system-x86_64 -cdrom ~/pan-os-iso/build/pan-os-booteable.iso

3. Recreate ISO:

   ./4-create-iso.sh

4. Rewrite USB:

   sudo dd if=~/pan-os-iso/build/pan-os-booteable.iso \
            of=/dev/sdb bs=4M

Issue: USB not recognized at boot

Causes:

• BIOS doesn't see USB
• USB not in boot priority
• BIOS in UEFI mode (need BIOS/Legacy)

Solutions:

1. Change BIOS settings:

   • Disable Secure Boot
   • Enable Legacy/CSM mode
   • Add USB to boot order
   • Save and reboot

2. Try different USB port

3. Create USB with different tool:

   # Using Etcher (GUI)
   balena-etcher-1.x.x
   # Select ISO → Select USB → Flash
   
   # Or Rufus on Windows

Issue: GRUB menu doesn't appear

Cause: Auto-boots to first entry (normal)

Solution:

• Hold SHIFT or ESC during GRUB to show menu
• Or wait - it boots in ~10 seconds

Issue: USB boots but kernel doesn't load

Cause: Initramfs mismatch or corruption

Solution:

1. Verify ISO integrity:

   md5sum ~/pan-os-iso/build/pan-os-booteable.iso

2. Recreate ISO:

   ./4-create-iso.sh

3. Rewrite USB completely:

   # Full wipe first
   sudo dd if=/dev/zero of=/dev/sdb bs=4M status=progress
   
   # Then write ISO
   sudo dd if=~/pan-os-iso/build/pan-os-booteable.iso \
            of=/dev/sdb bs=4M

Custom GRUB Configuration

You can modify boot options by editing GRUB config before ISO creation.

Edit: 1-build.sh → search for grub.cfg → modify boot parameters

Example: Add debug mode entry

menuentry "PanOS (Debug)" {
  insmod gzio
  insmod part_msdos
  insmod iso9660
  search --no-floppy --label PANOS
  linux /boot/vmlinuz console=ttyS0 debug loglevel=7
  initrd /boot/initramfs.cpio
}

Then recreate ISO:

./4-create-iso.sh

ISO Size Optimization

Current ISO: ~156 MB

To reduce size:

1. Remove debug symbols:

   • Edit kernel config to removeCONFIG_DEBUG_INFO

2. Compress better:

   • Use xz compression instead of gzip
   • Modify ISO creation script

3. Minimize busybox:

   • Select only needed commands
   • Use Alpine Linux instead

See 10-advanced.mdx for detailed customization.

Distributing PanOS

Share ISO Online

# Generate checksums
sha256sum ~/pan-os-iso/build/pan-os-booteable.iso > ISO.sha256

# Upload both files:
# - pan-os-booteable.iso (156 MB)
# - ISO.sha256

# Users verify:
sha256sum -c ISO.sha256

Create Recovery Media

Keep multiple copies:

1. Main USB - daily use
2. Backup USB - emergency
3. ISO file - archive
4. Network location - PXE boot

Next Steps

• Advanced Customization: Read 10-advanced.mdx
• Learn Architecture: Read 06-architecture.mdx
• Troubleshoot Issues: Read 08-troubleshooting.mdx

Previous: 08-troubleshooting.mdx
Next: 10-advanced.mdx