by acidanthera

acidanthera / NVMeFix
222 Stars 22 Forks Last release: 24 days ago (1.0.4) Other 109 Commits 5 Releases

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NVMeFix is a set of patches for the Apple NVMe storage driver, IONVMeFamily. Its goal is to improve compatibility with non-Apple SSDs. It may be used both on Apple and non-Apple computers.

The following features are implemented:

  • Autonomous Power State Transition to reduce idle power consumption of the controller.
  • Host-driver active power state management.
  • Workaround for timeout panics on certain controllers (VMware, Samsung PM981).

Other incompatibilities with third-party SSDs may be addressed provided enough information is submitted to the bugtracker.

Unfortunately, some issues cannot be fixed purely by a kernel-side driver. For example, MacBookPro 11,1 EFI includes an old version of NVMHCI DXE driver that causes a hang when resuming from hibernaton with full disk encryption on.


NVMeFix requires at least Lilu 1.4.1 and at least 10.14 system version. It may be compatible with older systems, but has not been tested.

It may be installed to

, or injected by the bootloader.


enables detailed logging for

disables the kext.

Some SSDs misbehave when APST is on. NVMeFix attempts to detect broken motherboard and SSD combinations and work around them. Motherboard is detected via IORegistry keys injected by Clover, or NVRAM variables provided by OpenCore.

APST table entries specify minimum idle latency for the transition to occur. Maximum acceptable latency is 100000 microseconds, and may be overriden via little-endian 8-byte property

of parent PCI device (e.g.
IOService:/AppleACPIPlatformExpert/[email protected]/AppleACPIPCI/[email protected],5/IOPP/[email protected]
). If set to 0, APST will be disabled completely.


build will only log high-level information about failures.

build will additionally log used power states, detailed error messages, and attempt to fetch APST status and table from the controller.

APST enable status is posted to the IONVMeController IORegistry entry


If active power management initialisation is successful, an

entry will be created in the IOPower IORegistry plane with IOPowerManagement dictionary.

Information about power states supported by the controller may be obtained e.g. using

. For example, in the following output the controller reports 5 states, where the former three high-power states will be used by NVMeFix for active power management, and the latter two may be used for APST depending on
Supported Power States
St Op     Max   Active     Idle   RL RT WL WT  Ent_Lat  Ex_Lat
 0 +     9.00W       -        -    0  0  0  0        0       0
 1 +     4.60W       -        -    1  1  1  1        0       0
 2 +     3.80W       -        -    2  2  2  2        0       0
 3 -   0.0450W       -        -    3  3  3  3     2000    2000
 4 -   0.0040W       -        -    4  4  4  4     6000    8000

IONVMeFamily supports the following debug flag bitfield, which are passed either via

bootarg or
1: Log some events via kprintf
2: Detailed event trace via kernel_debug with 0x61500xx debugid
4: PRP-related event trace via kernel_debug with 0x61540xx debugid
8: Force disable LPSR for Apple controllers
16: Perform only PCI initialisation of NVMe controller
32: Ignore initialisation errors
128: Disable LPSR for Apple controllers
512: Disable Unmap feature for IONVMeBlockStorageDevice

IONVMeFamily supports the following additional bootargs:

nand-io-timeoutms: Timeout for NVMe requests in ms, 35 s by default
enable-IO-log: Issue CORE_DEBUG_ENABLE_IOLOG ASP command (for Apple controllers)

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