Update README.md with AppleVTD section

Author: Mieze

README.md

@@ -7,7 +7,7 @@ OS X open source driver for the Realtek RTL8111/8168 family
 
 Due to the lack of an OS X driver that makes use of the advanced features of the Realtek RTL81111/8168 series I started a new project with the aim to create a state of the art driver that gets the most out of those NICs which can be found on virtually any cheap board on the market today. Based on Realtek's Linux driver (version 8.035.0) I have written a driver that is optimized for performance while making efficient use of system resources and keeping the CPU usage down under heavy load.
 
-Key Features of the Driver
+**Key Features of the Driver**
 - Supports Realtek RTL8111/8168 B/C/D/E/F/G/H found on recent boards.
 - Support for multisegment packets relieving the network stack of unnecessary copy operations when assembling packets for transmission.
 - No-copy receive and transmit. Only small packets are copied on reception because creating a copy is more efficient than allocating a new buffer.
@@ -19,43 +19,49 @@ TCP, UDP and IPv4 checksum offload (receive and transmit).
 - Support for Energy Efficient Ethernet (EEE) which can be disabled by setting enableEEE to NO in the drivers Info.plist without rebuild. The default is YES.
 - The driver is published under GPLv2.
 
-Limitations
+**Limitations**
 - As checksum offload doesn't work with jumbo frames on older versions of the RTL8111, jumbo frames are only supported on chiset 16 (RTL8111E-VL) and above.
 - No support for 32bit kernels.
 
-Installation
+**Installation**
 
 Before you install the driver you have to remove any installed driver for RTL8111/8168.
 
-- Goto /S/L/E and delete the old driver (Lnx2mac, AppleRealtekRTL8169, etc.).
-    
-- Recreate the kernel cache.
-    
-- Open System Preferences and delete the corresponding network interface, e. g. en0. If you forget this step you might experience strange problems with certain Apple domains, iTunes and iCloud later.
-    
-- Reboot.
-    
-- Install the new driver and recreate the kernel cache.
+- Use OpenCore or Clover to inject the driver.
 
 - Reboot
 
 - Open System Preferences again, select Network and check if the new network interface has been created automatically or create it manually now.
 
 - Configure the interface.
 
-Current status
+**Current status**
 
 The driver has been successfully tested under 10.8.2 - 10.15.6 with serveral versions of the RTL8111 and is known to work stable on these devices but you'll have to consider that there are more than 30 different revisions of the RTL8111. The RTL8111B/8168B chips have been reported to work since version 1.0.2 too.
 
-Support
+**A word on AppleVTD**
+
+Although RealtekRTL8111 supports AppleVTD since version 2.5.0d0, there is no guarantee that your mainboard also does. In case you are unsure if you need AppleVTD, leave it disabled and you'll be on the safe side. When you enable AppleVTD and experience one of the following issues, it's most likely that your board doesn't support AppleVTD:
+- Kernel Panics.
+- The machine suddenly reboots, freezes and/or the fans speed up.
+- No network connection at all.
+- The link status keeps going up and down.
+- Very low connection throughput.
+
+**What can you do to resolve the issue?**
+- Check your board's DMAR table and see if there are any reserved memory regions in it.
+- If there are reserved memory regions, you might want to patch your DMAR removing these regions. If it resolves the issue, congratulations! Be careful, because the board's manufacturer did add these regions with intention. Removing them may produce unexpected results too, like the problems described above.
+- Otherwise you have to keep AppleVTD disabled, because it is incompatible with your board and there is no way to make it compatible.
+
+**Support**
 
 Please refer to the driver's thread on insanelymac.com
 
 https://www.insanelymac.com/forum/topic/287161-new-driver-for-realtek-rtl8111/
 
 in case you have further questions, need support or want to submit a problem report. As of now, support requests here on Github will be ignored!
 
-Changelog
+**Changelog**
 
 - Version 2.5.0d2 (2025-02-05)
     - Added support for AppleVTD and restructured resource allocation.
@@ -116,7 +122,7 @@ Changelog
 - Version 1.2.0 (2014-04-23):
     - Updated underlying linux sources from Realtek to 8.037.00. Improved interrupt mitigate to use a less aggressive value for 10/100 MBit connections.
 
-Troubleshooting
+**Troubleshooting**
 - Make sure you have followed the installation instructions especially when you have issues with certain domains while the others are working fine.
 - Use the debug version to collect log data when trying to track down problems. The kernel log messages can be found in /var/log/system.log. For Sierra and above use "log show --predicate "processID == 0" --debug" in order to retrieve kernel logs. Include the log data when asking for support or giving feedback. I'm an engineer, not a clairvoyant.
 - Check your BIOS settings. You might want to disable Network Boot and the UEFI Network Stack as these can interfere with the driver.
@@ -127,28 +133,29 @@ Troubleshooting
 - Use Wireshark to create a packet dump in order to collect diagnostic information.
 - Keep in mind that there are many manufacturers of network equipment. Although Ethernet is an IEEE standard different implementations may show different behavior causing incompatibilities. In case you are having trouble try a different switch or a different cable.
 
-Help - I'm getting kernel panics!
+**Help - I'm getting kernel panics!**
+
 Well, before you start complaining about bugs after you upgraded macOS and ask me to publish a driver update, you should first try to resolve the issue on your own by cleaning the system caches.
 As the driver uses macOS's private network driver interface, which is supposed to be used by Apple provided drivers only, you might run into problems after an OS update because the linker may fail to recognize that IONetworking.kext has been updated and that the driver needs to be linked against the new version (Apple provided drivers avoid this problem because they are always updated together with IONetworking.kext). As a result, the linking process produces garbage and the driver may call arbitrary code when trying to call functions from IONetworking.kext. This usually results in unpredicted behavior or a kernel panic. In order to recover from such a situation, you should clean the System Caches forcing the linker to recreate it's caches:
     1. Delete all the files in /System/Library/Caches and it's subdirectories but leave the directories and the symbolic links intact. This is very important!
     2. Reboot.
     3. Recreate the kernel cache.
     4. Reboot again.
 
-FAQ
+**FAQ**
 - How can I retrieve the kernel logs?
     - In Terminal type "grep kernel /var/log/system.log".
 - I want to disable Energy Efficient Ethernet (EEE) but I don't know how?
     - Take a look at the driver's Info.plist file. There you will find an option named <key>enableEEE</key>. Change its value from <true/> to <false/>. Don't forget to recreate the kernel cache after changing the value.
 - WoL from S5 doesn't work with this driver but under Windows it's working. Is this a driver bug?
     - No it isn't, the driver is working as it should because OS X doesn't support WoL from S5.
 
-Known Issues
+**Known Issues**
 - There are still performance problems with regard to SMB in certain configurations. My tests indicate that Apple's Broadcom driver shows the same behavior with those configurations. Obviously it's a more general problem that is not limited to my driver.
 - WoL refuses to work on some machines.
 - Old systems with 3 and 4 series chipsets exhibit performance issues in recent versions of macOS because there is no optimized power management for these systems in macOS anymore as Apple dropped support for the underlying hardware a long time ago. In case you are affected, please upgrade your hardware or find an alternative solution because I have no plans for a workaround. Sorry, but I don't think that it's worth the effort.
 
-Building from Source
+**Building from Source**
 
 I'm always using the latest version of XCode for development. You can get a free copy of XCode after becoming a member of the Apple developer program. The free membership is sufficient in order to get access to development tools and documentation.