Use all USB3 ports of Intel DH87RL on El Capitan

Today I succeeded in enabling all of my Intel DH87RL motherboard's USB3 ports.

As it turns out, El Capitan's XHCI driver has a limit of 15 ports which was taken up by the board's USB2 ports, leaving just one USB3 port usable.

Since only 8 USB2 ports are actually physically accessible from the outside, disabling the unused ports makes more USB3 ports available.

In theory, this should happen automatically because OS X evaluates the board's DSDT which should flag the user-accessible ports. Needless to say, the DH87RL's DSDT is buggy, so this method fails. ioreg is a helpful tool to find out the current configuration.

Helpfully, Apple has implemented a port disabling feature to handle the case of buggy DSDTs. Examples can be seen by examining the existing plug-ins of the XHCI drivers, to be found at /System/Library/Extensions/IOUSBHostFamily.kext/Contents/PlugIns/AppleUSBXHCIPCI.kext/Contents/Info.plist. This file contains port specifications for each different computer model.

In order to create my own port specification for my DH87RL, I used the fact that the XHCI controller uses a label of 'XHC1' on Apple's DSDT's, while the DH87RL's XHCI is labelled 'XHC' by the DSDT. This allowed me to create my own kext by matching on the emulated model name 'iMac14,2' in combination with 'XHC'.

By trial and error I found out that the USB2 ports provided by the DH87RL are numbered 1, 2, 3, 4, 6, 8, 9 and A. I created a file /EFI/CLOVER/OEM/DH87RL/kexts/10.11/InjectUSB.kext/Contents/Info.plist with the following contents:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
 <key>CFBundleDevelopmentRegion</key>
 <string>English</string>
 <key>CFBundleGetInfoString</key>
 <string>1.0.1, Copyright © 2000-2014 Joki Inc. All Rights Reserved.</string>
 <key>CFBundleIdentifier</key>
 <string>org.joki.injector.usb.USBXHCIDH87RL</string>
 <key>CFBundleInfoDictionaryVersion</key>
 <string>6.0</string>
 <key>CFBundleName</key>
 <string>XHC1 injector for DH87RL</string>
 <key>CFBundlePackageType</key>
 <string>KEXT</string>
 <key>CFBundleShortVersionString</key>
 <string>1.0.1</string>
 <key>CFBundleSignature</key>
 <string>????</string>
 <key>CFBundleVersion</key>
 <string>1.0.1</string>
 <key>IOKitPersonalities</key>
 <dict>
  <key>iMac14,2-XHC1</key>
  <dict>
   <key>CFBundleIdentifier</key>
   <string>com.apple.driver.AppleUSBMergeNub</string>
   <key>IOClass</key>
   <string>AppleUSBMergeNub</string>
   <key>IONameMatch</key>
   <string>XHC</string>
   <key>IOProviderClass</key>
   <string>AppleUSBXHCIPCI</string>
   <key>IOProviderMergeProperties</key>
   <dict>
    <key>port-count</key>
    <data>FQAAAA==</data>
    <key>ports</key>
    <dict>
     <key>HS01</key>
     <dict>
      <key>UsbConnector</key>
      <integer>3</integer>
      <key>port</key>
      <data>AQAAAA==</data>
     </dict>
     <key>HS02</key>
     <dict>
      <key>UsbConnector</key>
      <integer>3</integer>
      <key>port</key>
      <data>AgAAAA==</data>
     </dict>
     <key>HS03</key>
     <dict>
      <key>UsbConnector</key>
      <integer>3</integer>
      <key>port</key>
      <data>AwAAAA==</data>
     </dict>
     <key>HS04</key>
     <dict>
      <key>UsbConnector</key>
      <integer>3</integer>
      <key>port</key>
      <data>BAAAAA==</data>
     </dict>
     <key>HS06</key>
     <dict>
      <key>UsbConnector</key>
      <integer>3</integer>
      <key>port</key>
      <data>BgAAAA==</data>
     </dict>
     <key>HS08</key>
     <dict>
      <key>UsbConnector</key>
      <integer>3</integer>
      <key>port</key>
      <data>CAAAAA==</data>
     </dict>
     <key>HS09</key>
     <dict>
      <key>UsbConnector</key>
      <integer>3</integer>
      <key>port</key>
      <data>CQAAAA==</data>
     </dict>
     <key>HS0A</key>
     <dict>
      <key>UsbConnector</key>
      <integer>3</integer>
      <key>port</key>
      <data>CgAAAA==</data>
     </dict>
     <key>SSP1</key>
     <dict>
      <key>UsbConnector</key>
      <integer>3</integer>
      <key>port</key>
      <data>EAAAAA==</data>
     </dict>
     <key>SSP2</key>
     <dict>
      <key>UsbConnector</key>
      <integer>3</integer>
      <key>port</key>
      <data>EQAAAA==</data>
     </dict>
     <key>SSP3</key>
     <dict>
      <key>UsbConnector</key>
      <integer>3</integer>
      <key>port</key>
      <data>EgAAAA==</data>
     </dict>
     <key>SSP4</key>
     <dict>
      <key>UsbConnector</key>
      <integer>3</integer>
      <key>port</key>
      <data>EwAAAA==</data>
     </dict>
     <key>SSP5</key>
     <dict>
      <key>UsbConnector</key>
      <integer>3</integer>
      <key>port</key>
      <data>FAAAAA==</data>
     </dict>
     <key>SSP6</key>
     <dict>
      <key>UsbConnector</key>
      <integer>3</integer>
      <key>port</key>
      <data>FQAAAA==</data>
     </dict>
    </dict>
   </dict>
   <key>model</key>
   <string>iMac14,2</string>
  </dict>
 </dict>
 <key>OSBundleRequired</key>
 <string>Root</string>
</dict>
</plist>

After reboot, I could use all of my USB3 ports (for reference, numbered 9, A, B, C, D and E).

A handy command to see the kernel boot messages is

$ log show --debug --last boot --style compact