M4 Macs can't virtualise older macOS

Original Article ↗ Hacker News Discussion ↗

Apple’s new M4-based Macs reportedly can’t virtualize macOS versions earlier than 13.4 Ventura, raising concerns among developers who rely on VMs to test software on older system releases. Commenters link this to Apple’s broader pattern of limited backward compatibility and tight control over virtualization and containers, which complicates CI pipelines and long-term support for apps and games. Opinions diverge on whether the limitation is a fixable bug or an intentional choice that prioritizes hardware and ecosystem lock-in over preserving older software.

Apple’s approach to backward compatibility

  • Many see Apple as consistently willing to drop old software/hardware support (PPC, 32‑bit, OpenGL, older macOS/iOS) in ways that break existing apps and games.
  • Others note Apple still leads in long official device support and aftermarket life, but agree post‑support compatibility is not a major priority.
  • Some argue this is rational: Apple optimizes for new hardware sales and simplicity, and is comfortable losing users who won’t adapt.

Virtualizing older macOS / iOS and 32-bit software

  • The article’s finding that M4 Macs can’t virtualize macOS < 13.4 is seen as a serious regression for devs and testers.
  • Use cases cited: CI, cross‑version QA, debugging behavior on older macOS, and niche tasks that require old system behavior.
  • On iOS, some wish they could run old 32‑bit apps in sandboxed containers; others point out AArch32 support is gone in hardware, so only heavy emulation is possible.
  • There’s debate over security and maintenance: keeping old OSes around, even sandboxed, increases attack surface and testing burden.

Bug vs intentional decision

  • Some commenters say Apple staff have called the M4 limitation an unintentional bug; others doubt this or can’t verify due to closed bug tracker access.
  • Another view is that documentation and Apple’s QA model (only guaranteeing the shipped OS) suggest this is intentional: they don’t want to support older guests on new chips.
  • Several expect low priority for any fix, since those macOS versions are now EOL.

Impact on development, CI, and containers

  • macOS is criticized as uniquely painful for CI: no native container tech comparable to Linux or Windows, restrictive licensing (only 2 macOS VMs per host), and reliance on third‑party tools.
  • Workarounds exist (VM products, Darwin containers, cross‑compilers), but people expect Apple to shut down anything that reduces hardware demand.
  • Some note Rosetta and virtualization have been a strength, but incompatibilities (e.g., missing newer x86‑64 instruction sets) already constrain build optimization.

Gaming and ecosystem comparisons

  • Several connect this to a broader pattern: deprecating OpenGL, Metal‑only strategy, and uncertain Rosetta future pushing games and some pro apps away from macOS.
  • Comparisons highlight Windows’ strong backward compatibility and Linux’s fragmented ABI situation, with trade‑offs in stability vs evolution.