USB 4.0 "USB4" Specification Published

[the_scx]

I wonder why USB never made a color code specification for cables / ports. IE, yellow ring for power only, blue for serial only, green for display, red for parallel / full spec. For the power spec orange could be "fast" charging capable up to the rated limit whereas yellow would only be up to the usual 5v.

Mac users would love it!

USB4 LGBTQIA

You know that it's not just about speed (Low Speed = 1.5 Mb/s, High Speed = 480 Mb/s, SuperSpeed = 5 Gb/s, SuperSpeed+ = 10 Gb/s | 20 Gb/s | 40 Gb/s) and charging (0.5 W = 5 V * 0.1 A, 0.75 W = 5 V * 0.15 A, 2.5 W = 5 V * 0.5 A, 4.5 W = 5 V * 0.9 A, 7.5 W = 5 V * 1.5 A, 9 W = 5 V * 1.8 A, 10 W = 5 V * 2 A, 15 W = 5 V * 3 A, 18 W = 12 V * 1.5 A, 25 W = 5 V * 5 A, 27 W = 9 V * 3 A, 36 W = 12 V * 3 A, 45 W = 15 V * 3 A, 60 W = 12 V * 5 A | 20 V * 3 A, 100 W = 20 V * 5 A), but also about alternate modes (USB = Universal Serial Bus Mode, DP = DisplayPort Alternate Mode, MHL = Mobile High-Definition Link Alternate Mode, TB = Thunderbolt Alternate Mode, HDMI = HDMI Alternate Mode, VL = VirtualLink Alternate Mode), right?
You will need a lot of colors to properly mark it. Do you think that customers would be happy with rainbow cables?

[torsionbar28]

None of the 1.X devices you mention are really in use anymore, though you can easily find them in junk piles at thrift stores, so it's not going to be a problem for any business, since they would have long since replaced such devices with USB 2.0 ones.

You underestimate the business world. I have customers with Compaq DL380 G2 servers, circa 2004, still in production service. We're talking Pentium 3 with 4 GB RAM and 146 GB SCSI drives. Yes they're also running EOL operating systems. No plans to upgrade, as they're not internet connected, and they have a big pile of spare parts to keep them alive. The manufacturing industry in particular is notorious for running ancient PC's to operate equally ancient manufacturing equipment. I worked on 486 DX2-66's for the tobacco processing industry until just a few years ago. I can understand their point - they have a 30 year old industrial machine that would cost $2M to replace with a new one. The software that runs the machine only runs on MS-DOS. Sure they could maybe do something fancy with virtualization, or DOSbox emulation, but what does that really gain them, other than added complexity, and factory downtime to upgrade/maintain a newer PC? Heck, most bank ATM machines are still running Windows XP. Anyways, I'm rambling now- the point is, I think you'd be quite surprised at the number of USB 1.x devices that are still in use today.

[elatllat]

... what does that really gain them...

$, a new $111 4w power sipping 14 nm box replacing 10 100w servers is going to save them some $ directly and in AC.


When do we get pure usb-c hubs?

[anth]

USB 3.2 ... 20Gb/s
USB 4.0 .. 40 Gb/s( doubles the bandwidth.. )

I've always thought the claims of extra bandwidth from TB compared with USB were a bit misleading. They are correct but with a caveat.

PCIe over Thunderbolt 3 has the same maximum 20Gb/s bandwidth per direction as the USB 3.x protocol. The difference is USB (3.2 Gen 2x2) uses the two SuperSpeed+ lanes in one direction and the other two lanes in the other direction, but only does one direction at a time rather than both at once. TB also uses two lanes in each direction but can do both at once, though it is limited to a length of 0.5m or an active cable.

DisplayPort 1.2 to 1.4 can use the HBR3 transmission mode from that standard as a USB-C alternate mode, with 1, 2, or all 4 SuperSpeed+ lanes, for a maximum bandwidth in one direction of 32.4Gb/s.

I've not got to grips with USB 4 yet.

[starshipeleven]

You know that it's not just about speed (Low Speed = 1.5 Mb/s, High Speed = 480 Mb/s, SuperSpeed = 5 Gb/s, SuperSpeed+ = 10 Gb/s | 20 Gb/s | 40 Gb/s) and charging (0.5 W = 5 V * 0.1 A, 0.75 W = 5 V * 0.15 A, 2.5 W = 5 V * 0.5 A, 4.5 W = 5 V * 0.9 A, 7.5 W = 5 V * 1.5 A, 9 W = 5 V * 1.8 A, 10 W = 5 V * 2 A, 15 W = 5 V * 3 A, 18 W = 12 V * 1.5 A, 25 W = 5 V * 5 A, 27 W = 9 V * 3 A, 36 W = 12 V * 3 A, 45 W = 15 V * 3 A, 60 W = 12 V * 5 A | 20 V * 3 A, 100 W = 20 V * 5 A), but also about alternate modes (USB = Universal Serial Bus Mode, DP = DisplayPort Alternate Mode, MHL = Mobile High-Definition Link Alternate Mode, TB = Thunderbolt Alternate Mode, HDMI = HDMI Alternate Mode, VL = VirtualLink Alternate Mode), right?
You will need a lot of colors to properly mark it. Do you think that customers would be happy with rainbow cables?

You need to mark only for speed and then add colors for the "highest speed available + power delivery level 1", "highest speed available + power delivery level 2" and so on.

All alternate modes can be folded into the "speed" category.

[starshipeleven]

USB 4.0 also features USB 2.0 data bus, so backwards compatibility is there, through USB 2.0's compatibility with 1.X. The real issue is driver support, as it won't likely be available in Windows 10 for such ancient devices. None of the 1.X devices you mention are really in use anymore, though you can easily find them in junk piles at thrift stores, so it's not going to be a problem for any business, since they would have long since replaced such devices with USB 2.0 ones.

A lot of modern USB keyboards and mice and controllers are actually USB 1.1, also other input devices using the HID generic drivers (i.e. disguising as controllers or keyboard/mouse) commonly use USB 1.1 as they don't need high bandiwth

Breaking USB 1.1 support is a BIG deal for input devices.

[starshipeleven]

1) the IOMMU unit on the CPU must be properly programmed. This is the job of the Linux kernel. Of course, it must be sponsored by the CPU manufacturer (Intel / AMD / ARM). Did their developers do the job?

IOMMU/VT-d needs to be enabled in UEFI settings, Linux supported it since a long time ago due to its usage in servers. This should block DMA attacks, assuming the IOMMU itself isn't vulnerable (which can and does happen, but still it's another layer of defence).

Additional hardening is available through a daemon that controls access of devices connected to the port https://github.com/gicmo/bolt
Similar daemons exist also for USB (usbauth).

2) The BIOS / UEFI must be fixed so that it does not allow being intercepted by disallowed devices.
...
Another option, the BIOS / UEFI must make use of IOMMU (never heard of it).

This is possible as UEFI is capable of using IOMMU for itself, or disabling DMA alltogether on PCIe while in UEFI stage (and losing access to devices needing it). https://firmware.intel.com/blog/upda...-uefi-firmware

From my limited understanding, Tianocore opensource UEFI implementation does support IOMMU https://github.com/tianocore/edk2/bl...e/IoMmuDxe.inf

But as all things UEFI, good fucking luck with that on most commercial hardware (i.e. there is no guarantee that anyone will do more than the bare minimum to get things working at all, and test only on Windows). Afaik most hardware is vulnerable to these attacks when in the UEFI stage (i.e. during boot)

Best candidates to get a device with a sane UEFI/firmware are companies that actually care and write their own device's UEFI (or try to use Coreboot), like System76 and Purism.

[brent]

Security hasn't been an issue with Thunderbolt for many years now. I don't get it why uneducated people still bring this up all the time. UEFI system firmwares (those that I know) have configurable Thunderbolt policies and OS support with opt-in policies for new devices is easy to enable (or even default), too. Of course IOMMU with proper configuration is a plus, but if security policies keep unwanted Thunderbolt devices separated from the host on the PCIe level, you don't need it.

[L_A_G]

So it is NOT backwards compatible with USB 1.0/1.1? That's a pretty glaring omission. There are tons of older HID devices, printers, label printers, and other devices that don't need much bandwidth and typically have a long service life. People gonna be pissed when they find this out the hard way.

I suspect that the idea is to let device makers include both older and USB 4.0+ ports for devices and then eventually just let consumers use cheap "legacy USB hubs" to support their legacy devices. There's only so much legacy cruft that you can have in your standard before it becomes unwieldy and unmanageable.

[tuxd3v]

I've always thought the claims of extra bandwidth from TB compared with USB were a bit misleading. They are correct but with a caveat.

PCIe over Thunderbolt 3 has the same maximum 20Gb/s bandwidth per direction as the USB 3.x protocol. The difference is USB (3.2 Gen 2x2) uses the two SuperSpeed+ lanes in one direction and the other two lanes in the other direction, but only does one direction at a time rather than both at once. TB also uses two lanes in each direction but can do both at once, though it is limited to a length of 0.5m or an active cable.
orrect but with a caveat.

PCIe over Thunderbolt 3 has the same maximum 20Gb/s bandwidth per direction as the USB 3.x protocol. The difference is USB (3.2 Gen 2x2) uses the two SuperSpeed+ lanes in one direction and the other two lanes in the other direction, but only does one direction at a time rather than both at once. TB also uses two lanes in each direction but can do both at once, though it is limited to a length of 0.5m or an active cable.

DisplayPort 1.2 to 1.4 can use the HBR3 transmission mode from that standard as a USB-C alternate mode, with 1, 2, or all 4 SuperSpeed+ lanes, for a maximum bandwidth in one direction of 32.4Gb/s.

I've not got to grips with USB 4 yet.
DisplayPort 1.2 to 1.4 can use the HBR3 transmission mode from that standard as a USB-C alternate mode, with 1, 2, or all 4 SuperSpeed+ lanes, for a maximum bandwidth in one direction of 32.4Gb/s.

I've not got to grips with USB 4 yet.

At Physical Layer , Thunderbolt3 has the same speed Limitation as USB3.2 over USB-C..
What turns it faster is the Paralel behavior in full duplex.. I agree
Also,
USB 3.2 on the 2 new modes SuperSpeed+, uses a 128b/132b encoding, which improves the transfers, but maybe give him a bit of latency, compared with the more conservative 8b/10b..