Last modified: Sat Jul 11 2020 18:18:28 GMT+0000 (Coordinated Universal Time)

Why OpenCore over Clover and others

  • Supported version: 0.5.9

This section is a brief rundown as to why the community has been transitioning over to OpenCore, for those who just want a macOS machine can skip this page.

1. OpenCore features

  • On average, OpenCore systems boot faster than those using Clover as less unnecessary patching is done
  • Better overall stability as patches can be much more precise:
  • Better overall security in many forms:
    • No need to disable System Integrity Protection(SIP)
    • Built-in FileVault 2 support
    • Vaulting allowing to create EFI snapshots preventing unwanted modifications
    • True secure-boot support(currently going through security audit, coming soon)
  • BootCamp switching and boot device selection are supported by reading NVRAM variables set by Startup Disk just like a real mac.
  • Supports boot hotkey via boot.efi - hold Option or ESC at startup to choose a boot device, Cmd+R to enter Recovery or Cmd+Opt+P+R to reset NVRAM.

2. Software Support

The biggest reason someone may want to switch from other boot loaders is actually software support:

  • Kexts no longer testing for Clover:
    • Got a bug with a kext? Many developers including the organization Acidanthera(maker of most of your favorite kexts) won't provide support unless on OpenCore
  • Many Firmware drivers being merged into OpenCore:
  • AMD OSX patches:
    • Have AMD based hardware? Well the kernel patches required to boot macOS no longer support Clover, only OpenCore

3. Kext Injection

So to better understand OpenCore's kext injection system, we should first look at how Clover works:

  1. Patches SIP open
  2. Patches to enable XNU's zombie code for kext injection
  3. Patches race condition with kext injection
  4. Injects kexts
  5. Patches SIP back in

Things to note with Clover's method is:

  • Calling XNU's zombie code that hasn't been used since 10.7, it's seriously impressive Apple hasn't removed this code yet
    • OS updates commonly break this patch, like recently with 10.14.4 and 10.15
  • Disables SIP and attempts to re-enable it, don't think much needs to be said
  • Likely to break with 10.16
  • Supports OS X all the way back to 10.5

So now lets take a look at OpenCore's method:

  1. Takes existing prelinked kernel and kexts ready to inject
  2. Rebuilds the cache in the EFI environment with the new kexts
  3. Adds this new cache in

Things to note with OpenCore's method is:

  • OS Agnostic as the prelinked kernel format as stayed the same since 10.6, far harder to break support.
    • This also means proper support starts at 10.7, though 10.6 can be used as well so long as it's already installed(106's installer doesn't have a prelinked kernel)
  • Far better stability as far less patching

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