Installation Requirements

Hardware and software prerequisites for installing to an actual system (bare metal). What you need before installing Forest OS: supported hardware, firmware settings, install media, and VM host prerequisites. Check everything here first — most install failures trace back to one of these rows.

If you only want to try in a VM, see the virtualization docs. This page covers real hardware installs.

Quick Checklist

• 64-bit (x86_64) or 32-bit (i686) PC with CPUID support
• 256MB+ RAM (512MB+ recommended, 1GB+ with GUI)
• 512MB+ disk (2GB+ recommended, 8GB comfortable)
• 2GB+ USB stick for installer (8GB+ for persistent live USB)
• BIOS/CSM or UEFI x64 firmware, Secure Boot OFF
• Second machine / working OS to download ISO and flash USB
• Backup of target disk completed

Install guides: Install on a VM · Install on Real Hardware · USB Persistence · Installation Overview

Contents

1. Quick checklist
2. Supported hardware
3. CPU details
4. RAM details
5. Disk / storage details
6. Firmware setup
7. Install media
8. Needed tools / software
9. VM host prerequisites
10. Networking
11. Backup reminder
12. Pre-install checklist

Supported hardware

ARM/AArch64/RISC-V guests boot with -kernel directly (no ForeB) and are serial-only. This page covers x86/x86_64 installs.

CPU details

• CPUID instruction is required. 486 and early 586 without CPUID will not boot.
• PAE is not strictly required for base install, but recommended for 32-bit systems with 4GB+ RAM.
• ARM, RISC-V, PPC, and other non-x86 CPUs are not supported by this installer.

Check on Linux:

grep -o 'cpuid\|lm' /proc/cpuinfo | sort -u
# lm flag = 64-bit (x86_64) capable

RAM details

• Installer itself needs ~256MB to unpack and run.
• Less than 256MB will likely panic, hang, or OOM during install.
• Swap is optional but recommended if RAM < 1GB (512MB–1GB swap partition).

Disk / storage details

Supported:

• Internal SATA / PATA / IDE HDD and SSD
• NVMe (if visible as /dev/nvme* to installer)
• USB HDD / SSD as install target (slower, but works)
• VirtIO / SCSI virtual disks (bare-metal pass-through / KVM hosts)

Not recommended as install target:

• SD cards / raw flash without wear-leveling (works but wears fast)
• The same USB stick you booted the installer from

Partitioning checklist:

• Target disk identified correctly (lsblk / fdisk -l)
• At least one partition for root (/)
• Optional: separate /home
• Optional: swap if RAM < 1GB
• No valuable data left on target disk

Firmware setup

Forest OS boots both ways from the same hybrid ISO:

• Disable Secure Boot. Forest OS ships an unsigned BOOTX64.EFI; with Secure Boot on, firmware refuses to load it.
• Set SATA to AHCI (not RAID/Optane/IDE) if the option exists. AHCI is the tested path.
• Fast Boot / Fast Startup: disable if the USB stick or ISO is not detected; it skips USB enumeration.
• Boot order: optical/USB first for install, internal disk first afterwards. On UEFI you may see two stick entries (UEFI: <stick> and USB: <stick>) — pick the one matching the path you want.
• Firmware set to BIOS/CSM or UEFI x64 mode; boot menu key known (F12 / F8 / Esc / Del — varies by vendor).

Checklist:

• Firmware set to BIOS/CSM or UEFI x64 mode
• Secure Boot DISABLED
• Fast Boot / Rapid Start DISABLED (if it skips USB boot)
• Boot order set to USB first, or boot menu key known
• SATA mode set to AHCI (not RAID / Optane) unless you have drivers for it

Install media

cd forest/fern
./conf.sh --defconfig && ./conf.sh --generate
make all
ls -lh ../foreboots/build/   # forebo.iso / forebo.img / esp.img

• A USB stick ≥ 256 MiB for the ISO itself (any USB 2.0/3.0 stick works; all data on it is erased). For installer use 2GB+; for live + persistent storage 8GB+. USB 2.0 works; USB 3.0+ recommended for speed.
• Write with dd on Linux (bs=4M oflag=sync + sync), or Rufus in DD mode on Windows — ISO mode extracts files and breaks the ForeB sector layout, so the stick will not boot. DVD/CD also works if ISO fits and drive is bootable, but USB is recommended.
• Verify before rebooting: MBR signature 55aa at bytes 510–511, stage2 magic 0xFEB1 at sector 1, kernel ELF magic (7F 45 4C 46) at the kernel sector. Full checks: Install on a VM.
• You need a second machine (or the same one booted into Linux/Windows) to write the USB.

Warning: dd to the wrong device destroys data. Triple-check of= with lsblk before every write.

Needed tools / software

You need a working machine (any OS) to prepare the installer:

Also needed:

• ISO image downloaded (plus checksum if provided)
• Checksum verified (sha256sum / certutil / Etcher verify)
• One empty USB stick (see sizes above)
• Keyboard + display attached to target machine (serial/headless only if image documents it)

VM host prerequisites

# QEMU (test, install target, rescue)
sudo apt install qemu-system-x86 qemu-utils ovmf xorriso mtools

# Verify KVM (strongly recommended — install without it is ~10x slower)
ls -la /dev/kvm
sudo usermod -aG kvm $USER   # re-login after

# Verify OVMF firmware files (paths vary by distro)
ls /usr/share/edk2/x64/OVMF_CODE.4m.fd /usr/share/edk2/x64/OVMF_VARS.4m.fd
# Debian/Ubuntu alt paths:
ls /usr/share/ovmf/OVMF.fd
ls /usr/share/OVMF/OVMF_CODE.fd

• QEMU needs split CODE + writable VARS pflash drives — copy VARS to a per-VM file, never point both at the same read-only file.
• Keep serial logging on (-serial stdio) — kernel banners and forinstall errors land there.
• VirtualBox: VBoxVGA display, IDE/SATA disk 2 GiB+, e1000/PCNet NIC. VMware: LSI Logic SCSI or SATA disk 2 GiB+, e1000 NIC, BIOS firmware for MBR installs or UEFI for ESP installs.

Networking

Optional, but recommended.

Bring if needed:

• Ethernet cable / LAN access
• Wi-Fi SSID + password
• Proxy URL / static IP details (only if your network needs them)

Backup reminder

Installing WILL WIPE the target disk.

• Full backup of target machine completed
• Backup verified (can list / restore files from it)
• Product keys / licenses / passwords exported
• Installer USB and target disk are different devices
• Unplug other external disks to avoid overwriting the wrong one

When in doubt: lsblk before and after plugging in the USB stick. The device that appears is the stick — never dd to a device you cannot re-identify. See Backup.

Pre-install checklist

• Back up the target disk — forinstall formats it. Confirm you picked the empty disk, never the installer media (cd0).
• Confirm display, keyboard, and network in the live session before installing.
• Keep ~100–200 MiB free on the root after install (df -h).
• Snapshot the VM (QEMU savevm, VirtualBox/VMware snapshot) right after the first successful boot, before experimenting.

See Also

• Installation Overview — install process at a glance
• Install on a VM — QEMU/VirtualBox/VMware walkthrough
• Install on Real Hardware — USB install, firmware setup, bootloader sectors
• USB Persistence — live vs persistent vs full USB install
• Installer — forinstall + forupdate reference
• Disk Tools — fdisk, mkfs, mount, fsck
• ISO Creation — hybrid ISO / IMG / ESP internals
• BIOS Boot — stage layout, sector map, error catalog
• UEFI Boot — ESP layout, forebo.cfg, chainloading

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