# What is HPTT?
HPTT (Hybrid PCIe Trace Tool) is inspired by HMTT (Hybrid Memory Trace Tool). HMTT, due to its direct connection to memory modules, has significant limitations that severely impact computer performance and user experience. Therefore, we integrated DMA technology and focused on PCIe, implementing a similar technology to HMTT on the PCIe bus. The core of this technology is to hide DMA functionality behind a legitimate PCIe device. This approach achieves DMA functionality without compromising computer performance. More importantly, the system will only detect the legitimate PCIe device you are using, and that device will retain all its original functionalities. To the system, it will only perceive that you have inserted this legitimate PCIe device, effectively concealing DMA and preventing its detection.

# How HPTT Works:
HPTT utilizes Xilinx GT channels to implement the PCIe Gen1/2 physical layer. We use a self-developed data link layer processing module to insert PCILeech DMA request packets into the data link without disrupting the normal operation of the device. Simultaneously, we analyze and separate DMA request results and data from the connected PCIe device (such as the wireless network card in the video) from the completed data packets. Unlike traditional PCIe switches, during the device enumeration process, the system only recognizes the Bus ID and Device ID of the PCIe sub-card (like the network card) mounted on the HPTT hardware. The configuration process and subsequent BAR read/write, memory requests, message packets, etc., are all handled by the mounted sub-card. HPTT solely manages the merging of PCILeech data requests with the mounted device’s data requests and performs traffic control.

In simple terms, HPTT conceals DMA within a legitimate and real PCIe device. The PCIe device you are using retains its original functions. The computer with HPTT installed will only detect this legitimate PCIe device and will not be able to detect DMA.

# Compatibility and Firmware:
HPTT supports almost all PCIe 1.0 and PCIe 2.0 x1 devices, though some compatibility issues may arise. We have tested several mid-to-high-end ASUS and MSI motherboards and have identified compatibility problems with certain PCIe devices. To address compatibility issues across different motherboard platforms and variations in operating modes among different types and models of mounted PCIe sub-cards, in the current software version, we tailor the HPTT firmware to match specific models of PCIe devices. For example, if your device currently uses firmware specific to the AX210 wireless network card, it will be compatible with any network card product from various manufacturers that shares the AX210 kernel model as the mounted device.

If you need to use a new device as the mounted device in the future (e.g., replacing the AX210 with a USB controller), we will need to adapt the firmware specifically for that device (the USB controller). Unlike traditional DMA firmware replacements, HPTT firmware modifications involve configuring the parameters of the internal channel merging and separation module. The primary purpose is to ensure compatibility with new devices, rather than simulating real device information as with traditional DMA. (We do not need to simulate, as we are using real and legitimate devices).

In future developments, we will gradually expand the firmware compatibility range from individual device models to entire device types (such as all wireless network cards or all USB controllers), and ultimately to all PCIe x1 PCIe devices – this is our ultimate goal.

*Open Ticket in Discord for more info.
Discord: https://discord.com/invite/CfU3B9gtmU