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Intel introduces Thunderbolt 4 combining the best of Thunderbolt 3 and USB4 with universal connectivity and enhanced security

Intel 8000 series Thunderbolt 4 controller. (Source: Intel)
Intel 8000 series Thunderbolt 4 controller. (Source: Intel)
Intel has announced the Thunderbolt 4 protocol and new Thunderbolt 4 controllers, which build on the capabilities of Thunderbolt 3 and also form the basis for the USB4 spec. Thunderbolt 4 offers the same throughput as Thunderbolt 3 along with additional platform and security features while also expanding the Thunderbolt dock ecosystem. Thunderbolt 4 will be compatible all existing USB Type-C and Thunderbolt 3 standards and will be first seen in Tiger Lake-powered laptops later this year.

Back during Computex 2019, Intel talked about integrating the capabilities of Thunderbolt 3 into the USB4 specification. Later that year, the USB4 spec was finalized with an aim to lessen the confusion between various USB types and allowing use of a standard USB Type-C connector. Today, Intel is officially taking wraps off the Thunderbolt 4 (TB 4) standard. Thunderbolt 4 will now be the basis for the USB4 protocol while also offering a few additional features on top of the standard USB4 spec. 

Thunderbolt 4 will be the base for the USB4 spec. (Source: Intel)
Thunderbolt 4 will be the base for the USB4 spec. (Source: Intel)

Thunderbolt 4 features

Thunderbolt 4 brings no changes to the total throughput — we still get the same 40 Gb/s bandwidth that Thunderbolt 3 offered. However, the requirements for a device to be certified for Thunderbolt 4 have now changed. For instance, a TB 4 device will now support two 4K displays or one 8K display with a PCIe data throughput at 32 Gb/s. Other requirements include that at least one of the TB 4 ports on the PC should allow for charging and the ports should allow the PC to wake up from standby. TB 4 also uses Intel VT-d for Direct Memory Access (DMA) protection.

Unlike USB4, which offers a choice between 20 Gb/s and 40 Gb/s throughput, TB 4 is always 40 Gb/s and uses a common Type-C connector that allows for all capabilities offered by the protocol including DisplayPort-out and power delivery.

Thunderbolt 4 features. (Source: Intel)
Thunderbolt 4 features. (Source: Intel)
A Thunderbolt 4 port can support all of the platform's functions. (Source: Intel)
A Thunderbolt 4 port can support all of the platform's functions. (Source: Intel)
Thunderbolt 4 cables are universal. (Source: Intel)
Thunderbolt 4 cables are universal. (Source: Intel)
 

How Thunderbolt 4 is different from Thunderbolt 3

As discussed earlier, TB 4 builds upon TB 3 and offers parity with the USB4 spec. The table below illustrates the differences between the various USB specs available. The additional features offered by TB 4 include the support for 40 Gb/s cables from 0.2 m to 2 m in length. Intel said that it is looking to expand cable length to 5 to 50 m in the future. TB 4 now mandates that the PC or laptop support dual 4K display outputs, PCIe bandwidth of 32 Gb/s (2x that of the requirement of TB 3), and support for VT-d among others.

Intel said that TB 4 can be implemented irrespective of the processor type without any licensing fees, which means upcoming ARM-based Macs as well as future AMD processors are also likely to offer TB 4 support. 

Intel is also introducing a new controller for TB 4. The Intel 8000 series TB 4 controllers include the JHL8540 and JHL8340 host controllers for PC OEMs, and the JHL8440 controller for accessory makers. The new 8000 series TB 4 controllers will make their debut in PCs and accessories later this year starting from the upcoming Tiger Lake laptops including the ones made according to the Project Athena guidelines.

Thunderbolt 4 builds upon the Thunderbolt 3 spec. (Source: Intel)
Thunderbolt 4 builds upon the Thunderbolt 3 spec. (Source: Intel)
Comparison between Thunderbolt 4 and other USB protocols. (Source: Intel)
Comparison between Thunderbolt 4 and other USB protocols. (Source: Intel)
Thunderbolt 4 uses the new 8000 series controllers for PCs and accessories. (Source: Intel)
Thunderbolt 4 uses the new 8000 series controllers for PCs and accessories. (Source: Intel)
 

Thunderbolt 4 accessories

Intel said that a wide range of accessories for TB 4 would be made available starting later this year. All TB 4 docks can offer up to four TB 4 ports. TB 4 now supports a multi-port accessory architecture wherein a single dock will now be able to connect to dual 4K displays, allow for external PCIe SSDs with storage speeds up to 3,000 MB/s and still offer enough bandwidth for connecting additional peripherals. Devices using TB 3 and multiple USB standards can be daisy-chained together in whatever manner the user pleases and all these devices will interface with the PC via a single TB 4 port.

(Source: Intel)
(Source: Intel)
(Source: Intel)
(Source: Intel)
(Source: Intel)
(Source: Intel)
 

Thunderbolt 4 security

TB 4 makes it mandatory that PC and Macs support Intel Virtualization Technology for Directed I/O or simply, VT-d. VT-d is built into most modern Intel processors and is essentially a method to prevent peripherals from unauthorized memory access. This is important as USB Type-C allows for connecting PCIe devices externally just as they were installed internally, and these devices are capable of DMA without having to involve the CPU. What Intel VT-d does is that it remaps DMA (DMA-r) and isolates a designated memory region for each connected peripheral. This prevents the peripheral from reading or writing to other parts of memory that aren't its own. 

Support for VT-d and DMA remapping is present in Windows 10 1803 and above (Kernel DMA Protection), MacOS 10.8.2 and above, and Linux kernel version 4.21 and above.

Source(s)

Intel Press Brief

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> Notebook / Laptop Reviews and News > News > News Archive > Newsarchive 2020 07 > Intel introduces Thunderbolt 4 combining the best of Thunderbolt 3 and USB4 with universal connectivity and enhanced security
Vaidyanathan Subramaniam, 2020-07- 8 (Update: 2020-07- 8)
Vaidyanathan Subramaniam
I am a cell and molecular biologist and computers have been an integral part of my life ever since I laid my hands on my first PC which was based on an Intel Celeron 266 MHz processor, 16 MB RAM and a modest 2 GB hard disk. Since then, I’ve seen my passion for technology evolve with the times. From traditional floppy based storage and running DOS commands for every other task, to the connected cloud and shared social experiences we take for granted today, I consider myself fortunate to have witnessed a sea change in the technology landscape. I honestly feel that the best is yet to come, when things like AI and cloud computing mature further. When I am not out finding the next big cure for cancer, I read and write about a lot of technology related stuff or go about ripping and re-assembling PCs and laptops.