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Displayport != Thunderbolt. Displayport is a protocol that can run over a thunderbolt port, but the thunderbolt spec includes much more than that. I don' beli

Displayport != Thunderbolt. Displayport is a protocol that can run over a thunderbolt port, but the thunderbolt spec includes much more than that. I don' believe we'll be seeing the 40Gbps PCI extension that is today's thunderbolt over USB 3.1.

ajross 12y ago
You're getting too tied up in brand identity and going too far in the other direction. What we call "Thunderbolt" is effectively an evolution of the DisplayPort PHY (which already supported graphics streaming of course, and also encapsulated USB transfers) with protocol extensions to do more PCI-like transactions. And the USB 3.1 "SuperSpeed+" PHY is a 10Gbps thing that is very comparable to Thunderbolt electrically and would be expected to evolve similarly. You're right that USB lacks the PCI framework (which many of us view as a feature). But DP/Thunderbolt similarly lacks a cabling standard with the sophistication of USB: no charging, not reversible connectors, no OTG-style switching of host/guest mode. Apple had a choice of supporting both connectors, or giving up "PCI madness" or "nice cables" to get just one. They picked USB.
- mikeash 12y ago
  That's all well and good, but the question was whether it supported actual Thunderbolt, to which the answer given was "yes" but the actual answer appears to be "no." Supporting something like Thunderbolt is nice, but not exactly the same. It's not about "brand identity," it's about "does this equipment I have work with this machine?"
  - ajross 12y ago
    That's hardly unique to this situation though. It doesn't support Firewire or eSATA or VGA or ethernet or AppleTalk or Centronics parallel either. Life moves on, and this is hardly a company gripped by concerns for backwards compatibility.
    - mikeash 12y ago
      You seem to have confused "Is this the end of Thunderbolt as well?" with "I hate Apple forever for changing things." It's a simple question with a simple answer. (Yes.)
    - zoul 12y ago
      Life moves on, but Thunderbolt is such a new interface to be obsoleted.
  - lsaferite 12y ago
    Just to clear up the FUD, the Type-C connector supports 'Alternate Modes.' This allows manufactures to implement chips that can MUX different signal types onto the USB cable SS lanes. There are 4 SS lanes that can be reassigned and either 2 or 5 additional wires that can also be used depending on if it's a cable or dock connection. So, can the Type-C connector support Thunderbolt? Yes. Does the Type-C connector currently support Thunderbolt? No. Will someone add Thunderbolt over Type-C? Maybe. I've only heard of PCIe over Type-C (via the spec docs) and DP over Type-C (from the VESA guys).
    - mikeash 12y ago
      It certainly sounds like an excellent connector. If Apple can shoehorn Thunderbolt into that, it would be great. If they can't, it sounds like it's well worth it anyway.
- moe 12y ago
  They picked USB. And thank goodness they did. The "U" in USB may finally become reality. It's overdue.
- beagle3 12y ago
  Does this mean that Thunderstrike (and previous PCI-based attacks) are not usable against the new Mac?
  - ajross 12y ago
    No, there is no access to PCI address spaces over the USB 3 port. At least not yet, with existing hardware. As mentioned elsewhere in the thread it's not an impossibility to see an evolved (but compatible) standard in future USB 3 hardware.
lsaferite 12y ago
So, in alternate mode all 4 SS lanes can be reassigned. Each lane is doing 10Gbps right now from what the specs say. You could do PCIe over this and they even use PCIe as an example in the Type-C spec documents.

ajross 12y ago

You're getting too tied up in brand identity and going too far in the other direction. What we call "Thunderbolt" is effectively an evolution of the DisplayPort PHY (which already supported graphics streaming of course, and also encapsulated USB transfers) with protocol extensions to do more PCI-like transactions. And the USB 3.1 "SuperSpeed+" PHY is a 10Gbps thing that is very comparable to Thunderbolt electrically and would be expected to evolve similarly. You're right that USB lacks the PCI framework (which many of us view as a feature). But DP/Thunderbolt similarly lacks a cabling standard with the sophistication of USB: no charging, not reversible connectors, no OTG-style switching of host/guest mode. Apple had a choice of supporting both connectors, or giving up "PCI madness" or "nice cables" to get just one. They picked USB.

mikeash 12y ago
That's all well and good, but the question was whether it supported actual Thunderbolt, to which the answer given was "yes" but the actual answer appears to be "no." Supporting something like Thunderbolt is nice, but not exactly the same. It's not about "brand identity," it's about "does this equipment I have work with this machine?"
- ajross 12y ago
  That's hardly unique to this situation though. It doesn't support Firewire or eSATA or VGA or ethernet or AppleTalk or Centronics parallel either. Life moves on, and this is hardly a company gripped by concerns for backwards compatibility.
  - mikeash 12y ago
    You seem to have confused "Is this the end of Thunderbolt as well?" with "I hate Apple forever for changing things." It's a simple question with a simple answer. (Yes.)
  - zoul 12y ago
    Life moves on, but Thunderbolt is such a new interface to be obsoleted.
- lsaferite 12y ago
  Just to clear up the FUD, the Type-C connector supports 'Alternate Modes.' This allows manufactures to implement chips that can MUX different signal types onto the USB cable SS lanes. There are 4 SS lanes that can be reassigned and either 2 or 5 additional wires that can also be used depending on if it's a cable or dock connection. So, can the Type-C connector support Thunderbolt? Yes. Does the Type-C connector currently support Thunderbolt? No. Will someone add Thunderbolt over Type-C? Maybe. I've only heard of PCIe over Type-C (via the spec docs) and DP over Type-C (from the VESA guys).
  - mikeash 12y ago
    It certainly sounds like an excellent connector. If Apple can shoehorn Thunderbolt into that, it would be great. If they can't, it sounds like it's well worth it anyway.
moe 12y ago
They picked USB. And thank goodness they did. The "U" in USB may finally become reality. It's overdue.
beagle3 12y ago
Does this mean that Thunderstrike (and previous PCI-based attacks) are not usable against the new Mac?
- ajross 12y ago
  No, there is no access to PCI address spaces over the USB 3 port. At least not yet, with existing hardware. As mentioned elsewhere in the thread it's not an impossibility to see an evolved (but compatible) standard in future USB 3 hardware.

lsaferite 12y ago

So, in alternate mode all 4 SS lanes can be reassigned. Each lane is doing 10Gbps right now from what the specs say. You could do PCIe over this and they even use PCIe as an example in the Type-C spec documents.