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Lenovo ThinkPad T420 with UEFI Only

* * * * * 17 votes UEFI ThinkPad T420 Lenovo Clover

Best Answer tluck, 08 October 2013 - 02:47 PM

02-March-2015 Update

  • Updated to Clover r3185 - compiled to remove text before GUI
  • Bumped VoodooPS2Controller.kext to v1.8.14 (to stay current)

09-February-2015 Update

  • Updated to Clover r3168 - compiled to remove text before GUI
  • Added ACID SMC key in FakeSMC.kext Info.plist for AC power support in Yosemite (custom install pkg included see Utility folder)
  • Recompiled ACPIBatteryManager.kext (for the heck of it)
  • Added universal time registry fix for dual boot with Windows for consistent time.
  • Tweaked _kext_install script to fix/recreate symbolic links for custom kexts.

Oct-Dec 2014 Updates

  • Updated FakeSMC.kext to v6.14.1364 for better Yosemite support  (included install pkg to install HWMonitor.app)
  • Updated VoodooPS2Controller to v1.8.13 (has T420 configuration in Info.plist files - and is more consistent with RehabMan's code Branch)
  • Updated ACPIBatteryManger.kext to v1.55 (to be consistent with latest rev)
  • Using VBoxHfs-64.efi instead of HFSPlus-64.efi
  • Added a DSDT for T420s vs T420 (provided by pokenguyen)
  • Consolidated kexts into Other folder vs 10.10, 10.9 since they are all the same.
  • ThinkPad Theme - minor tweaks to add Yosemite 2014.  This theme revised and committed to Clover source tree.
  • Updated select kexts - AppleHDA_20672.kext fixed for 10.10.2 dependency (works for 10.9. and 10.10)
  • Removed drop MCFG table from config.plist files.
  • Tweaked config to actually use NVRAM boot drive selection on startup. (Can specify startup disk in System Prefs and restart will use it.)
  • Tweaked config (add kernel location for Yosemite) so boot without caches works.
  • Recompiled VoodooPS2Controller.kext v1.8.13 with added Lenovo T420 sections for Keyboard/TouchPad/TrackPoint
  • Added Platforms.xml file for use with Docking Station (and No-Dock default) option in AppleHDA_20672.kext
  • New custom kexts AppleHDA_20672.kext (fixed since October 13) and BroadcomBluetooth_T420.kext are added. Huge thanks to vladichimescu for showing me this kext method.
  • All custom/extra kexts are OS version independent and go in /Systems/Library/Extensions 
  • New Clover config.plist files for on-the-fly HDA kext patching. No need to replace any kexts after updates anymore.
  • Removed EmuVariableUefi-64.efi driver to use native NVRAM (vs /nvram.plist) - see note below on how to migrate.
  • Added drop table DMAR so VT-d does not have to be disabled
  • ACPIBacklight.kext - v2.0.3 - with modified code to fix/workaround for LCD brightness in Yosemite.
  • Note: To make an Mavericks USB installer, just follow the Yosemite method

Lenovo T420 Clover Guide


Attached is a current zip file with a complete /EFI pack for the Lenovo T420 using Clover on OS X versions:

  • 10.10  Yosemite
  • 10.9    Mavericks

Why Clover vs Chameleon?

  • Native UEFI boot support for OS X and Windows on GUID/GPT disks.
  • Native Apple OS X Installers and App Store Updaters. 
  • Supports Recovery HD for system recovery and iMessage, Find My Mac, etc.
  • Dynamic DSDT and Kext patching.


My system is a T420 with 1600x900 LCD and dedicated Intel HD 3000 Graphics Only.  This is a zip contains what is working for me on my specific model. The guide outlines the 2 phases: (1) how create a USB installer and install OSX, and (2) run OSX for your HD. If your HW is not similar as mine, the included DSDT and configuration files may need to be retrofitted to work for your system.  The models T420s, T420i as well as the T520 family may work as is or need some changes to the DSDT.



  • A current File Bundle for 10.9 or later is here in the zip file attached to the bottom of this post
    • Full Clover File set - config.plist + required custom kexts + custom DSDT
  • There are 2 configuration file sets: 
    • for high-res LCD (1600x900)
    • for low-res LCD  (1366x768)
  • Non-maintained Mountain Lion Kext Bundles for 10.8.4 are in post #241 and 10.8.5 in post #397




BIOS settings:

- Recommend update to BIOS v1.46

- Recommend reset to defaults. Most defaults settings will work but check settings these:

- Set Config / Serial ATA (SATA) / SATA = AHCI 

- Set Security / Memory Protection / Execution Prevention = Enabled

- Disable Discrete Nvidia/Optimus (use integrated HD 3000 only - unless you really know what you are doing!)


Note: The custom DSDT is based off BIOS v1.46 (flashed with whitelist mod or original)


Part 1 - OS Installation


  1. Download and extract the zip file from this post to build a Clover-based USB installer. This same bundle will be installed later on HD for UEFI boot.
  2. Install OS X to a GUID/GPT formatted disk using the standard Install OSX .app downloaded from the Apple Store.
  • Copy Mavericks (10.9.x) and Yosemite (10.10.x) to USB installer
  1. Download latest Yosemite or Mavericks - they are free in the Apple App Store
  2. Partition an 8GB (or larger) USB formatted as GUID - use option menu to change from MBR - name this partition USB
    Note: if you format the USB as MBR, then you will need to install the Clover boot tools (after) - see note at the bottom.
    Note: if you have a larger USB (say 16GB) you can split into 2 8GB partitions, so you can have 10.9 and 10.10 installers on the same USB key
  3. Run this command (if Mavericks, the replace word Yosemite with Mavericks):
    sudo /Applications/Install\ OS\ X\ Yosemite.app/Contents/Resources/createinstallmedia --volume /Volumes/USB --applicationpath /Applications/Install\ OS\ X\ Yosemite.app —nointeraction
  • Put Clover installation on USB
  1. manually mount ESP of USB and copy the entire EFI folder (from the zip) onto USB ESP
    For example, assuming the USB is disk2:

    sudo mkdir /Volumes/ESP-USB
    sudo mount -t msdos /dev/disk2s1 /Volumes/ESP-USB
    sudo cp -a ~/Downloads/T420/EFI /Volumes/ESP-USB

    Note: run "diskutil list" on the command line to find your USB disk
             if your USB is MBR format - just copy the EFI structure to the / (root) of the main partition instead!


  2. Setup configuration files to match your LCD resolution in /Volumes/ESP-USB/EFI/CLOVER:
    1. ​​​Rename ACPI.1600x900 to ACPI or rename ACPI.1366x768 to ACPI
    2. Rename config.1600x900.plist to config.plist or rename config.1366x768.plist to config.plist
  • Boot from USB and select Install OSX
  1. Install on your GUID disk - OSX partition.
  2. Wait about 30 minutes plus or minus.
  3. Follow these Notes and Tips:
  • When the installer screens shows:   "To pair a Bluetooth keyboard, turn it on and wait for your computer to connect to it.”

    Hit the Space Bar to get past this step.

  • When installer seems to hang at:  "About a second remaining”

    Don’t Panic, this "second" may take about 10 minutes or more to finish. Just wait for the installer to reboot the computer and continue the installation.The whole install process takes about 1 hour to complete.

  • On the first boot from the HD when asked:  "How Do You Connect?”

    Select: “My computer does not connect to the Internet”And set up the network later after installation the NIC driver kext.And your Intel WiFi will not work. Period. 

TIP: Enable debug mode for Disk Utility to see all the partitions (such as hidden EFI). From the Terminal command line, run this:

defaults write com.apple.DiskUtility DUDebugMenuEnabled 1

Part 2 - Post OS Installation and Setup on HD

  1. Boot Clover from USB - but now select the newly installed disk/partition to start OS X. 
    Note: This will boot up OS X with Clover injecting the custom kexts from the USB (for now). 

  2. Install Clover on HD 

    a ) Run the full Clover_v2k_rxxxx.pkg to install the related latest bits into the HD OS and ESP (usually partition 1) of disk0. Use the link to download the pkg from SourceForge.  You can do this step later on if you don't have way to get it before you are setup on the network. Select (check box) at least first 2 items! This picture shows a good set of overall options:
    [attachment=159590:clover-pkg-options.png]  After you close the pkg installer, then follow these step:

    b ) REPLACE the ESP (EFI folders) contents with the exact CLOVER folder as used in the setup on USB from steps above. If not still automatically mounted by the installer pkg, manually mount the ESP of your HD on say /Volumes/ESP. Then copy and replace the folders /Volume/ESP/EFI/CLOVER and BOOT from the USB installer you just built and used.

    Note: Yosemite likes to make a logical volume and this may confuse the Clover Installer looking for the ESP. So I recommend revert you root partition to a regular volume. Run: 
    sudo diskutil corestorage revert /
  3. Install custom kexts on HD
    • Recommended: Use the folder with its config.plist with the custom dsdt.aml (as is) to start.  And install the custom kexts from the zip folder to the /System/Library/Extensions folder. 

      Install these kexts from the zip folder EFI/CLOVER/kexts/Other by either method:
      - if you don't have a GUI, use the included shell script _kext-install-SLE.bash
      - if you have a GUI, then use the Kext Utility tool (from cvad included in Utilities folder). 

      Note: If you choose to NOT install the custom kexts in the OS /S/L/E folder, then AppleHDA and BroadcomBluetooth kexts will not work properly. You can also install custom kexts in /Library/Extensions if you dont want to put them in /System/Library/Extensions

  4. Install (copy) the DisplayVendorID-* folders
    These are from the zip file and should be put in /System/Library/Display/Overrides
    Note: These provide alternate color correction and gamma curves as well as more screen sizes for just a few LCD models. 

  5. Reboot - Boot Clover from HD vs USB.
    Hit the spacebar on your boot selection (OSX) to start up
     without kext caches to make sure it loads all the custom kexts just installed. 

  6. Ethernet Device Install
    Note: This step is optional but usually needed after a fresh OS install.
    This loads the ethernet kext and resets network device order to have ethernet as en0 (may help with iMessage etc)
    Run this set of commands in a terminal window:

    sudo kextload /System/Library/Extensions/AppleIntelE1000e.kext
    sleep 10
    sudo rm       /Library/Preferences/SystemConfiguration/NetworkInterfaces.plist
  7. Create a custom SSDT (optional)  
    Creates P and C states to match system CPU. Test against Clover generated SSDT PM tables - may be the same performance lately. (Long ago Clover had some issues here.)
    Run the custom ssdtPRgen-clover.command script in Zip Utilities folder. It should ask you if you want copy ssdt.aml to your ESP ACPI/patched folder, otherwise copy/move ssdt.aml to the same location as your custom dsdt.aml 
    which is: /Volumes/ESP/EFI/CLOVER/ACPI/patched

    Note: it will copy iasl from the Utility folder to /usr/local/bin/iasl

  8. Reboot a final time to use the new SSDT table (and other changes from last 3 steps)


Known Issues and Random Tips:

  • The stock Intel WiFi will not work. There are options to replace and use modded bios.

  • Clover may present 2 options for main OS partition if using Logical Volume vs Standard Volume. Revert the logical volume as Yosemite likes to install now on the boot disk, so Clover will not get confused and present duplicate options. Just "revert" using: 

    sudo diskutil corestorage revert /
  • Enable (turn on) Bluetooth so the green light is showing on the LCD bezel (do from Windows or Ubuntu).
    • Also make sure the side switch is set to green too!
  • When using external headphones or speakers, may need to plug and unplug 1 or 2 times for recognition.
  • E1000e ethernet hang: with the 2.5.4d and 3.x version of the Intel E1000e ethernet kext, I have seen some random problems. I rolled back to v2.4.14 and have not had issues lately. The issue occurs under heavy file copy/transfers and your ethernet stops working with a lot of log messages that only a reboot fixes. 
  • iMessage/Facetime may not register without overriding the Clover generated values with real ROM and MLB values from a real Apple Mac. Search thread for ROM to get more info.
    • Clover now (~r3050+) can possibly generate proper values and inject using RtVariables - use mac address -- see wiki for details.
  • With ACPIBacklight.kext installed, boot with lid open or LCD will be black when you open it.
  • After installing the kexts to /S/L/E, sometimes the symbolic link for the binary in AppleHDA_20672.kext and BroadcomBluetooth_T420.kext gets messed up. Fix by running this script:
  • cd /System/Library/Extensions/AppleHDA_20672.kext/Contents/MacOS
    sudo rm AppleHDA
    sudo ln -s /System/Library/Extensions/AppleHDA.kext/Contents/MacOS/AppleHDA
    cd /System/Library/Extensions/BroadcomBluetooth_T420.kext/Contents/MacOS
    sudo rm BroadcomBluetoothHostControllerUSBTransport
    sudo ln -s /System/Library/Extensions/IOBluetoothFamily.kext/Contents/PlugIns/BroadcomBluetoothHostControllerUSBTransport.kext/Contents/MacOS/BroadcomBluetoothHostControllerUSBTransport
    sudo touch /System/Library/Extensions
  • Hibernation does not wake from stored image with OsxAptioFixDrv-64.efi - suggested setting:
    sudo pmset -a hibernatemode 0
    rm /var/vm/sleepimage
  • OR if you really need hibernation, use (experimental) OsxAptioFix2Drv-64.efi instead of OsxAptioFixDrv-64.efi UEFI driver and set hibernate mode to 7 (like 3 with no encryption)

    sudo pmset -a hibernatemode 7

Note: booting from hibernated image may have jumbled LCD until one sleep/wake (non-hibernated) cycle.


Notes on Custom Kexts


All the kexts listed below are contained in the zip file. The origin is listed below if you wish to download them as well. I recommend you use kext install tool to properly copy all kexts to the /S/L/E (/System/Library/Extensions) folder.

  • FakeSMC.kext (v6.x.xxxx) - Core hack mechanism. Using Kozlek's version + plugins + custom FakeSMC Info.plist
    A Custom package is included in the Utilities folder 
    so you can install HWMonitor.app - it just selects these 2 Plugins Sensors: ACPI and CPU.
    • 2 Custom SMC keys are added to Kozlec's standard FakeSMC - FNum (to find the Fan) and ACID (for AC power and eliminate powerd syslog messages every 30 seconds).
  • AppleIntelE1000e.kext (v2.4.14) - Ethernet (gigE) - can go in /System/Library/Extensions vs Plugins so OSX re-installations or patch updates will not delete it.
  • VoodooPS2Controller.kext (v1.8.14) - T420 version of RehabMans's PS2 Keyboad/TouchPad/TrackPoint -  This version has extra T420 definitions in the Info.plist files. 
    • Modified Info.plist(s) to add LENOVO T420 key and override settings.
    • TrackPad pressure FingerZ value set to 47 - up from default of 30  - change to suite your touch in VoodooPS2Controller.kext/Contents/PlugIns/VoodooPS2TrackPad.kext/Contents/Info.plist
    • Note: VoodooPS2Controller keyboard mappings have 3 or 4 finger swipe left/right to back/forward configured for Safari browser.
  • ACPIBatteryManager.kext (v1.55) - RehabMan's kext configured for v3 ACPI instructions to show/track battery info on menu bar
  • ACPIBacklight.kext (v2.0.3) - RehabMan's kext for smoother/enhanced LCD backlight (dimming) control. The fix is for a Yosemite quirk.
  • GenericUSBXHCI.kext (v1.2.8d9) - RehabMan's version. Use for some USB3 express cards, if not natively supported by OS X.
  • IOAHCIBlockStorageInjector.kext -  configured to make just the DVD device appear internal so iDVD player works. 
  • BroadcomBluetooth_T420.kext (v999.99) - adds ProductID 8575 to make BT work better (on/off capability). Keep original/modified BroadcomBluetooth plug-in and add this kext to /S/L/E.
  • AppleHDA_20672.kext (v999.99) Keep original/unmodified AppleHDA.kext and add this kext to /S/L/E for full audio support for CX20672 (same as CX20590). Note: requires matching DSDT sections for Conexant Codec and layoutID 12. and Kext Patch via Clover. Also has Manwe150's fix/additions for dock ports. Credit and thanks to vladichimescu. 

    There are 2 files in AppleHDA_20672.kext/Contents/Resources 

    The "dock" version adds the second audio output called "Headphones" and a second Input "Line In" - both of which are on the Docking Station itself. 
    - IF you have a dock - then just replace the Platforms.xml.zlib file with Platforms.xml.zlib.dock
    - IF you DO NOT have a dock, then use the new kext as is! (and not be confused by the extra Input/Output options!!!)

​General Notes, Fixes, and Features

  • Clover configuration files (config.plist) 
     a ) config.plist                   - (default) to use the custom DSDT and WITH extra Clover patching
     b ) config.nodsdt.plist    - this testing version - everything works except battery levels
                                                       - remove/rename DSDT.aml and use built-in/BIOS DSDT with Clover patching
  • Model is to set MacBookPro8,1 explicitly in config.plist. (needed to get proper DP/HDMI/DVI/VGA FrameBuffers)
  • Zip includes extra and custom kexts plus cVad's Kext Utility v2.5.7 for easy kext installation (or you can use manual script:  _kext-install-SLE.bash)
  • Optionally use ssdtPRgen-clover.command script so you can create your own SSDT P/C state tables
  • Note: the High-res vs low-res config.plist (and DSDT) are the same - difference is EDID and DualLink settings.
  • Note: for 1600x900 the EDID is injected by Clover and is also in the 1600x900 version of the DSDT for - there are 2 sets of timings for 60 and 50 Hz options
  • Added folder for Displays/Overrides (for more natural color gamma curves and more screen size options) in this zip
  • Clover patches string for SNBFrameBuffer kext to fix LCD brightness max level - now its the same brightness before and after sleep. Thanks to Timewalker75a (again!)
    Note: this same kext patch replaces the 4th port/buffer (DVI on dock) with VGA on left side. The 4 ports after patch are: LCD, DisplayPort on side, DisplayPort on dock, VGA on side. If you need DVI on the dock - then you can either not do this! Or replace the 3rd port (DP) if you want the VGA.
  • Has a newer Thinkpad theme - for Mavericks and Yosemite Icons.
  • Here are some Special keys on laptop (without USB or Bluetooth keyboard): 
    • The ScrLk and Pause keys change LCD brightness - which are F14 and  F15 (above F10 and F11).
    • Insert key is the CD/DVD eject. 
    • The Blue ThinkVantage button toggles fan to highest speed.
    • The Alt key is the Mac Command key and Microsoft flag key is the Mac Option key.
    • Fn PgUp - still turns on the light!

DSDT Notes - Some of the DSDT tweaks (beyond manwe150's original version) are listed here:

  • DSDT includes source and binary
  • For 1600x900 LCD, the EDID override removes infamous HD 3000 glitches and buffer hangs or so-called artifacts.

  • Added MaxBeepBootVolume to DSDT to rid AppleHDA assertion on startup

  • Shutdown fixes in DSDT  _PTS and _WAK (thanks to TimeWalker75, RehabMan and Manwe150)

  • Change/fixes to reset LEDs for proper sleep/wake status

  • Battery fixes to use native/current ACPIPlatform.kext with Rehabman's ACPIBatteryManager.kext - no need to rollback or patch AppleACPIPlatform.kext anymore.

  • PNLF additions from RehabMan provide smoother/wider LCD backlight control with ACPIBacklight.kext

  • DSDT mods to KBD device - renamed to PS2K and added LENOVO OEM-ids for VoodooPS2Controller to use.
  • The PS2 Keyboard is identified as id LENOVO table-id T420 which will pickup the custom VoodooPS2Controller settings.

  • Included is a revised Pike's  SSDT generation script (sdtPRgen-clover.command) and a local copy of iasl. running the script will end with making a copy of ssdt.aml into proper ESP location when mounted.

EmuVariableUefi-64.efi migration to native NVRAM


1) Before updating if you are still using EmuVariable.efi, run this command see and then save current nvram values:

nvram -p
nvram -xp > ~/nvram.plist

2) Update the ESP with new Clover version (from zip or pkg) - uncheck EmuVariableUEFI-64 driver option.

3) Rename (or remove) EmuVariable driver the ESP so it will not be loaded on next boot, if there is one still in the Clover driver folder.  

Note: manually mount ESP on /Volumes/EFI or /Volumes/ESP, if not already mounted and then run:

mv /Volumes/ESP/EFI/CLOVER/drivers64UEFI/EmuVariableUEFI-64.efi /Volumes/ESP/EFI/CLOVER/drivers64UEFI/EmuVariableUEFI-64.efi.NU

4) Reboot and restore previous nvram values and remove Clover NVRam variable. You should see some variables already in there.

nvram -p
sudo nvram -xf ~/nvram.plist
sudo nvram -d Clover.NVRamDisk

5) Reboot to boot run with final values! 


Old issues - no longer happening. 

These 4 problems listed below happened with earlier versions of Clover and OS X  but on 10.9.2 or later, and with the rewrite of Clover and OsxAptopFixdrv-64.efi, these UEFI/ESP issues are seem to be a thing of the past.

  1. putting to sleep can result in flashing/hung state

  2. built-in keyboard mute button can totally freeze system - works fine from software (i.e. apple bluetooth KB)

  3. shutdown may not go all the way to full power off (OS shuts down but at black screen with fans/lights on)

  4. built-in PS2 keyboard/trackpad may disappear after sleep/wake 

Optional: Boot with Clover on MBR USB


One can still boot from the HD using UEFI. But one can also create a bootable MBR formatted USB with CloverEFI. This boot method may mitigate any random UEFI issues. The exact same EFI folder can be used. To make a bootable MBR USB:

  1. Format the stick as MBR (which is usually the default) with a single FAT32 partition named USB.
  2. Optionally copy the OSX installer to USB (same command for GUID USB above) but must be done before steps below!
  3. Then with Clover_v2k_rxxxx.pkg, install to the USB for "legacy CloverEFI" boot.  That is: Uncheck the top 2 items, and in Bootloader check the 2nd option to install boot0af.
  4. After the Clover pkg installer is finished and closed, then replace the EFI/CLOVER folder just like you did on the HD. the EFI/BOOT folder is not needed. Note: the HD ESP EFI folder and USB EFI folder should be exactly the same now.
  5. Then from the BIOS, set USB-HDD as top boot option (so you don't have manually boot from USB vs the HD)
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- whoops i updated the link for MBP8,1

- well the /EFI/APPLE/EXTENSIONS folders can't hurt anything - i think maybe that's where it looks to check for the stuff. i just have the 1 file in there - firmware.scap

- just to be sure, i would run the diskutil (in debug mode to see hidden partitions) to mount and repair your EFI System Partition



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Today I upgrade my T420s to FHD with a LVDS-eDP convertor. I also update EDID in DSDT and config.plist.

It works very well. Thanks everyone.


Here is my dsdt and config.plist. My LCD is B140HAN01.2 FHD now.


Attached File  T420s.1.38-FHD.zip   20.99KB   2 downloads


This is the convertor.


Attached File  convertor.png   1.17MB   2 downloads


This is Yosemite.


Attached File  Screen.png   239.16KB   1 downloads


The convertor only supports T420s/T430s now, because of the free space in laptop.

Also tagged with one or more of these keywords: UEFI, ThinkPad, T420, Lenovo, Clover

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