Partitioning and boot-loader changes can make macOS unbootable. Back up with Time Machine first.
What you will achieve
Understand how to run Linux alongside macOS — and platform limits on Apple Silicon.
Dual-boot means two operating systems on one disk, chosen at startup. On Intel Macs this is mature but fiddly. On Apple Silicon it is experimental or virtualised. Treat native dual-boot as an advanced project with erase risk, not a weekend tweak.
1) Intel Mac dual-boot
- Time Machine backup first — partitioning risks data loss.
- Shrink APFS in Disk Utility to create unallocated space.
- Boot Linux USB with Option (⌥) held at startup.
- Install to free space; use rEFInd if you need a boot menu.
2) Apple Silicon reality
M-series Macs cannot natively dual-boot standard Linux. Options:
- Asahi Linux for supported M1/M2/M3 hardware (check compatibility list).
- UTM, Parallels, VMware Fusion for virtualised Linux.
- Docker Desktop for container workloads.
3) Filesystem rules
Never install Linux onto the macOS APFS volume. Use separate partitions or VMs. exFAT is for file exchange only.
4) Recovery safety net
Know Recovery entry: power-button hold (Apple Silicon) or ⌘R (Intel). Keep a macOS installer USB if you experiment with boot loaders.
5) Disk space planning
Linux root plus swap plus home needs 40–80 GB minimum for desktop use. Shrinking APFS live is possible when free space exists inside container — if internal disk is full, offload to external storage before partitioning. Always screenshot Disk Utility layout before repartitioning.
6) Secure Boot and reduced security
Apple Silicon Linux experiments may require Startup Security Utility in Recovery → Reduced Security and permissive external boot. Understand you are widening attack surface — revert after testing. Intel Macs without T2 have fewer firmware gates but still use EFI passwords optionally.
7) Maintenance reality
macOS updates can reclaim boot-loader space or reset NVRAM boot order — keep macOS as primary OS and treat Linux as hobby partition unless you document recovery after each macOS upgrade.
Verify
Both environments boot reliably; macOS backups still run.
Additional troubleshooting notes
If steps above do not resolve the issue on the first attempt, reboot once, confirm System Settings → General → Software Update is current, and retry with a second administrator account to rule out profile or keychain corruption in your daily user. Document exact error text from Console.app with timestamp — vague “it still fails” without logs wastes support time. On Apple Silicon, re-test after full shutdown (not just restart) because firmware and Thunderbolt controllers reset only on cold boot. Intel Macs should repeat test in Safe Mode to bypass third-party login items. Before erase or keychain reset, verify Time Machine or clone backup completed — batch 3 guides assume Monterey/Ventura/Sonoma/Sequoia paths in System Settings; search Spotlight for renamed panes if your macOS version labels differ slightly.