Early 2011 13" MacBook Pro (Intel HD Graphics 3000) driving TWO or THREE external monitors - Thunderbolt 1 awesomeness

[Amethyst1]

No, your eyes do not deceive you - that's a 2011 13" MacBook Pro with integrated Intel HD 3000 graphics driving two external monitors (a 23.8" Dell P2415Q and a 21.5" LG UltraFine 4K) in an extended desktop configuration. But how is this possible, given the machine only has one Mini DisplayPort / Thunderbolt 1 port?

Well, the thing is - two discrete DisplayPort "streams" are available via Thunderbolt 1. How to extract them? The answer is: a Thunderbolt dock. But a dock will only extract one video signal. To extract the second signal, you need... two daisy-chained Thunderbolt docks. Yes, really.

So here's the setup:

Starting with the first dock on the left (which I got today - more on that one to come in the other thread I made):

• The black Thunderbolt cable (fourth, starting left) connects to the MacBook Pro.
• The white Thunderbolt cable (third, starting left) connects to the second dock on the right.
• The HDMI cable (second, starting left) connects to the first monitor.
• The power cable (first, starting left) connects to... well, you know.

Moving on to the second dock on the right (that's the one I've already talked about):

• The white Thunderbolt cable (fourth, starting left) comes from the first dock.
• The black Mini DisplayPort cable (third, starting left) connects to the Wacom Link Plus (that small box on the right).
• The black USB cable (second, starting left) also connects to the Wacom Link Plus.
• The power cable (first, starting left)... well, you know.

Ain't this complicated enough? What in the world does the Wacom Link Plus do? It converts Mini DisplayPort and USB-A to USB-C DisplayPort Alternate Mode - which is the only way to get a video signal into the UltraFine.

So, what happens is that a Thunderbolt "stream" goes from the MacBook Pro into the first dock. It extracts the first video signal and provides it via HDMI, which is what the Dell monitor is being run off of. Additionally, the first dock sends another Thunderbolt "stream", encapsulating the second video signal, on to the second dock. That extracts it and provides it via Mini DisplayPort, going to the Wacom Link Plus and, consequently, the LG monitor.

And there you have it. Two external monitors driven directly by the poor HD 3000. Yes, they're both "4K" monitors (of course - this is me ) but the HD 3000 can only do that resolution at 30 Hz (OOTB), so I ran them at 2560×1440 at 60 Hz. It's worth noting that since the HD 3000 only has two outputs, this configuration makes the MacBook Pro's internal LCD go blank, as shown in the first picture.

This is one of three ways to run two external monitors from a 2011 MacBook Pro's, or Mac mini's, single Thunderbolt 1 port:

1. Two Apple Thunderbolt Displays.
2. One Apple Thunderbolt Display + one Thunderbolt dock + one non-Thunderbolt display.
3. Two Thunderbolt docks + two non-Thunderbolt displays. (What I did.)

(No, you can't run two non-Thunderbolt displays from a single Thunderbolt 1 or 2 dock!)

 

[joevt]

Well, the thing is - two discrete DisplayPort "streams" are available via Thunderbolt 1 on this machine. How to extract them? The answer is: a Thunderbolt dock. But a dock will only extract one video signal. To extract the second signal, you need... two daisy-chained Thunderbolt docks. Yes, really.

And there you have it. Two external monitors driven directly by the poor HD 3000. Yes, they're both "4K" monitors (of course - this is me ) but the HD 3000 can only do that resolution at 30 Hz (OOTB), so I ran them at 2560×1440 at 60 Hz. It's worth noting that since the HD 3000 only has two outputs, this configuration makes the MacBook Pro's internal LCD go blank, as shown in the first picture.

Yup. It's not until Thunderbolt 3 that you get a single Thunderbolt controller that can convert two tunnelled DisplayPort connections.

Thunderbolt 1 is known for having 10 Gbps of data but actually it has two Thunderbolt channels for a total of 20 Gbps. Thunderbolt 1 doesn't have the ability to combine both channels to get 20 Gbps. Combining the channels as Thunderbolt 2/3/4 does allows for more efficient sharing between tunnelled PCIe and tunnelled DisplayPort.

2560x1440 60Hz 10bpc is ≈ 7.2 Gbps (5.8 Gbps for 8bpc) so your setup with two displays must be using more than 10 Gbps so you are definitely using more than one Thunderbolt 1 channel.

What I don't know is all the ways the multiple Thunderbolt devices can be assigned to one of the two channels.

I suppose you could try doing ATTO Disk Benchmark tests with multiple drives to see if you can get past 10 Gbps using tunnelled PCIe instead of tunnelled DisplayPort.

4K 60Hz is 16 Gbps so the only way you could get that is if the DisplayPort signal can bypass the Thunderbolt 1 controller. The Thunderbolt 1 controller would not be able to send that to a Thunderbolt 2 dock.

This is one of three ways to run two external monitors from a 2011 MacBook Pro's (or Mac mini's) single Thunderbolt 1 port:

1. Two Apple Thunderbolt Displays.
2. One Apple Thunderbolt Display + one Thunderbolt dock + one non-Thunderbolt display.
3. Two Thunderbolt docks + two non-Thunderbolt displays. (What I did.)

(No, you can't run two non-Thunderbolt displays from a single Thunderbolt 1 or 2 dock!)

An Apple Thunderbolt display is the equivalent of a Thunderbolt dock + display, so option 1, 2, and 3 are basically the same.

You should be able to get two displays from a single Thunderbolt 3 dock. Or maybe not. I think the Thunderbolt 3 dock would need to be able to work with two separate Thunderbolt 1 channels instead of a combined channel, otherwise the displays would need to be 1080p. I've never had a Thunderbolt 1 Mac to test this.

 

[Amethyst1]

2560x1440 60Hz 10bpc is ≈ 7.2 Gbps (5.8 Gbps for 8bpc) so your setup with two displays must be using more than 10 Gbps so you are definitely using more than one Thunderbolt 1 channel.

TB1 encapsulates DisplayPort 1.1a so I'll try two displays at 3840×2160 41Hz (~360 MHz pixel clock using CVT-RB) each next (the HDMI port might not go that high though).

I suppose you could try doing ATTO Disk Benchmark tests with multiple drives to see if you can get past 10 Gbps using tunnelled PCIe instead of tunnelled DisplayPort.

I'll see what I can do. BTW, the USB 3.0 controller (a Fresco Logic FL1100 again) in the newer TB2 dock gets full 5 GT/s, so I'll see what my SSD does when connected to that one.

4K 60Hz is 16 Gbps so the only way you could get that is if the DisplayPort signal can bypass the Thunderbolt 1 controller. The Thunderbolt 1 controller would not be able to send that to a Thunderbolt 2 dock.

I wonder what the situation is like with e.g. an iMac or MacBook Pro with a Kepler or Haswell GPU (DP 1.2) but TB1 (DP 1.1a). Can you get 4K at 60 Hz via DP passthrough? Update: No. All TB1 Macs with DP 1.2-capable GPUs use Cactus Ridge. Redwood Ridge, while TB1, supports DP 1.2 passthrough.

You should be able to get two displays from a single Thunderbolt 3 dock. Or maybe not. I think the Thunderbolt 3 dock would need to be able to work with two separate Thunderbolt 1 channels instead of a combined channel

I can try this - once TB3 docks have come down a bit in price... Would a TB3 to dual DisplayPort adapter be sufficient to test? This one explicitly says it's not backwards-compatible with TB2 though.

An Apple Thunderbolt display is the equivalent of a Thunderbolt dock + display, so option 1, 2, and 3 are basically the same.

That's the point. The Thunderbolt Display only has very slow USB 2.0 ports though, so a USB 3.0 dock is better in that regard.

 

[Amethyst1]

You should be able to get two displays from a single Thunderbolt 3 dock.

FWIW I found a dual-display Thunderbolt 2 dock.

 

[joevt]

FWIW I found a dual-display Thunderbolt 2 dock.

That must use two Thunderbolt controllers chained together inside the dock. It should appear as two Thunderbolt devices in System Information.app.

 

[LightBulbFun]

ooh thats cool! I knew that TB could carry multiple streams like that and people had gotten multiple displays/TB displays going on TB macs like that

but I did not realise it worked with the HD 3000 MBP8,1, I knew it had 2 Display outputs from the iGPU but was not sure if it could be rerouted like that, I had only seen it done on dGPU machines and the such like


so its very interesting see, especially so that it blanks the internal display, I figured apple would have forced the internal LCD to always be on and only drive 1 ext display and then only drive 2 in clamshell mode, turning off the internal LCD seems like a very un apple like thing if that makes sense

so thats interesting


now im curious does this setup work in 10.6.8? I know 10.6.8 supports the MBP8,1 and thunderbolt so in theory it should

 

[joevt]

TB1 encapsulates DisplayPort 1.1a so I'll try two displays at 3840×2160 41Hz (~360 MHz pixel clock using CVT-RB) each next (the HDMI port might not go that high though).

HDMI 1.4 is limited to 340 MHz for 8bpc 4:4:4. DisplayPort 1.1 doesn't support 4:2:0 but can do 4:2:2. I'm not sure if the Intel GPU can do 4:2:2 (there's no way to select it manually - you'll want to try Windows for that kind of test - install the Intel Graphics Control Panel and the later Intel Graphics software but I don't know how well Windows works with Thunderbolt 1). Depending on the macOS version, the log stream or log show command can show what pixel formats the OS tests for each resolution/refresh rate when it's creating the list of modes for a newly connected display.

I'll see what I can do. BTW, the USB 3.0 controller (a Fresco Logic FL1100 again) in the newer TB2 dock gets full 5 GT/s, so I'll see what my SSD does when connected to that one.

Did you try the fast.sh script with the 2.5 GT/s FL1100?

I wonder what the situation is like with e.g. an iMac or MacBook Pro with a Kepler or Haswell GPU (DP 1.2) but TB1 (DP 1.1a). Can you get 4K at 60 Hz via DP passthrough? Update: No. All TB1 Macs with DP 1.2-capable GPUs use Cactus Ridge. Redwood Ridge, while TB1, supports DP 1.2 passthrough.

Well, DisplayPort pass thru doesn't require Thunderbolt controller pass thru support if you can completely bypass it using DisplayPort mux switches. Remember, with enough chips and code you can do anything in a computer (but space inside a laptop is limited). I guess you have to look at supported resolutions for all TB1 Macs to see if any can do more than 4K30 or 2K60.

I can try this - once TB3 docks have come down a bit in price... Would a TB3 to dual DisplayPort adapter be sufficient to test? This one explicitly says it's not backwards-compatible with TB2 though.

Any Thunderbolt 3 device with a DisplayPort output and a Thunderbolt output or second DisplayPort output should work. A Thunderbolt 3 to Dual DisplayPort adapter will work if it's connected to a Thunderbolt 3 device since you cannot use a Thunderbolt 3 to Thunderbolt 2 adapter directly (the dual display adapter has a male USB-C cable that cannot be disconnected).

That's the point. The Thunderbolt Display only has very slow USB 2.0 ports though, so a USB 3.0 dock is better in that regard.

Yup, or a USB 3.1 gen 2 dock which can get you ≈750 MB/s with Thunderbolt 1 which is better than ≈450 MB/s of USB 3.0 but not as good as 1000 MB/s of full USB 3.1 gen 2.

With Thunderbolt 3, you can force Thunderbolt 2 speed (20 Gbps x1 link width x2) using the Apple Thunderbolt 3 to Thunderbolt 2 Adapter or a USB-C cable.
I don't know of a way to force Thunderbolt 1 speed except to damage the cable and remove one of the lanes but that only gets you 10 Gbps x1 (link width x1) mode instead of the Thunderbolt 1's 10 Gbps x2 (link width x1) mode.
You can force a Thunderbolt 3 controller's upstream to PCIe 2.0 (to simulate better a Thunderbolt 1/2 controller) or even PCIe 1.1 (using the fast.sh script) but none of these changes affect the Thunderbolt 3 controller's ability to take DisplayPort 1.2/1.4 input (except the bandwidth limit of Thunderbolt 2/1 speed).

Maybe there's some Thunderbolt controller registers that can disable channel aggregation. The Alpine Ridge doc that turned up in the forums may have that info.

 

[Amethyst1]

now im curious does this setup work in 10.6.8? I know 10.6.8 supports the MBP8,1 and thunderbolt so in theory it should

Sure does

I had to use a different monitor for the DisplayPort connection as 10.6.8's HD 3000 kext causes a kernel panic if a 4K monitor in DP 1.2 mode is connected via DisplayPort. The Asus can be switched to DP 1.1 mode which avoids the panic but the UltraFine can't (which means you can't use it with 10.6.8 on an HD 3000-equipped Mac). The panic doesn't occur on 10.7.5 or later versions with the HD 3000; no panic on 10.6.8 with a GeForce 320M, Radeon 4850 or 6870 either.

Edit: The MBP was on battery power the whole time LOL!

 

[joevt]

Interesting how there's no Thunderbolt Speed or Link Width numbers shown. Does that mean 10.6.8 doesn't know about Thunderbolt 2 which can have Link Width x2? Maybe, since 10.6.8 was released July 25, 2011. At least Thunderbolt 2 devices are backwards compatible with Thunderbolt 1 hosts.

Also missing are Route String, Receptacle, Mode, Upstream port indicator. I wonder how well Thunderbolt 1 controller registers match with the Alpine Ridge registers? If they are similar enough, then that info can be extracted by software.

 

[Amethyst1]

Does that mean 10.6.8 doesn't know about Thunderbolt 2 which can have Link Width x2?

10.6.8 through 10.8.5 have no idea about Thunderbolt 2; the first Macs to have Falcon Ridge shipped with 10.9.
Link Width came with 10.9. Here's what System Profiler's Thunderbolt section shows with regards to the docks in...

10.8.5:

10.9.5:

10.13.6:

 

[joevt]

10.6.8 through 10.8.5 have no idea about Thunderbolt 2; the first Macs to have Falcon Ridge shipped with 10.9.
Link Width came with 10.9. Here's what System Profiler's Thunderbolt section shows with regards to the docks in...

10.8.5:


10.9.5:


10.13.6:

Interesting.

Even in Big Sur, Upstream doesn't show link width for Thunderbolt 1 devices (I have Apple Thunderbolt to FireWire Adapter and Apple Thunderbolt to Ethernet Adapter).

Route String appears to be a list of two digit numbers (the first number is a single digit because leading zero is removed?). Each number is a Thunderbolt port number. You can see Thunderbolt port numbers in ioreg.

 

[bunnspecial]

This one hits a bit close to home for me, as a 2011 MBP was my first Mac and one of only two over the years I've bought new. It served me while, along side other Macs, was mostly replaced by a 2012 15"(9,1), and the latter was replaced earlier this year by an M1 Pro.

In any case, a desktop such as my maxed out 5,1 isn't a great option for me right now, but I need a computer that can run SL-natively run it and not virtualized. Of course the 2011 MBPs fit the bill for this, and the late 2011s work just fine as long as you have the 10.6.7 restore disk that shipped with the early 2011s(I have a couple, although ended up making an installer on a USB stick). I don't want to dump all the data on my MBP 8,1, but carved out a 50gb SL partition for it and it's running fine, although High Sierra is still its "main" OS so to speak.

All of that rambling aside, though, after a year of working from home(and mostly not now) I'm finally getting a home office set up, albeit while I'm waiting for a desk to arrive I'm using a 6 foot table. I bought a fancy OWC TB3 dock, which can charge my M1 along with giving me tons of useful ports and other add-ons. In testing, though, sure enough(via a TB2-TB3 adapter) it works perfectly with my 8,1 in 10.13, and gives full USB 3.0 support.

Initially I set this up with a 27" Apple Cinema, which is a monitor I still like. Back in the day, though, I always wanted a Thunderbolt display. They're the same panel as the Cinemas and really look all but identical, but of course at the time were also one of the few TB docks around. I finally broke down and bought one-they can be had for around $200 shipped on Ebay with some patience.

That made me realize that all of the above was possible-the TB display itself is a TB hub, so when it arrived today, I worked it onto my "desk"(a bit snug on space, but it fit) then hooked it to the TB3 dock by way of a TB2-TB3 adapter. For ease of set-up at the time, I then used a second TB2-TB3 into the dock from the 8,1. Sure enough, booted into High Sierra, it all came to life

And yes, that is the SL wallpaper on the right display. I have been known to use wallpaper from older versions of OS X because I like them, and with the pleasant side effect of annoying @LightBulbFun . The left screen has the ML wallpaper.

For now, the TB display has displaced the Cinema display on my desk, as can be seen there's really not enough room comfortably for two displays. The TB display has some nice benefits like giving me a FW port(how many people have FW on their M1 Macs?). Also the TB display bumped to a 720p "Facetime Camera" and not the 480p "iSight" of the Cinema(I've been feeling weird using Zoom with the cinema since the camera is terrible compared to the one on any of the laptops I use, but it means having to either not face the camera or have to look at the laptop screen...). Overall it's a good upgrade. I'd make two displays work if the M1 could actually drive them.

As another side-note on the dock-SL sees it, but it's completely dead. It just registers as a bunch of devices for which there aren't drivers, which isn't surprising. Unfortunately, though, I'd hoped at least the mini-DP split off would work, but it doesn't.

I do want to set this all back up, though, with my 11" MBA for maximum enjoyment

 

[Amethyst1]

how many people have FW on their M1 Macs?)

Heck yeah!

Unfortunately, though, I'd hoped at least the mini-DP split off would work, but it doesn't.

One of my docks is Thunderbolt 2 and SL doesn’t recognise any of its devices - DisplayPort extraction works fine though.

 

[bunnspecial]

Okay, a bit of a follow up...

Pulled out my 2011 11" MBA(such a cute little computer...) and it worked fine with the TB display/USB dock/etc.

I plugged a second display in to the mini-DP on the TB dock, and nothing.

That's consistent with this report from 2011 https://www.macrumors.com/2011/09/16/apple-thunderbolt-display-with-multiple-monitors/

I'd initially wondered if it was a VRAM thing as the MBA only allocates 384mb and the MBP uses 512mb, but @LightBulbFun thinks it has to do with a different TB controller in the MBA.

 

[Amethyst1]

I plugged a second display in to the mini-DP on the TB dock, and nothing.

The 2011 MBA has the cut-down "Eagle Ridge" Thunderbolt controller. That has only one DP input/output (driven by the GPU) and therefore can’t handle two displays. The 2011 MBP uses the full-blown "Light Ridge" with two DP inputs/outputs.
https://www.anandtech.com/show/4528/the-2011-macbook-air-11-13inch-review/4

 

[Amethyst1]

There's something else you can do with two outputs: combine them to smash the barriers of a single output

Starting point: The 2011 MBP cannot do 3840×2160 at 60 Hz. All it does is an utterly unusable 30 Hz. But... two daisy-chained Thunderbolt docks provide two independent outputs (one DisplayPort, one HDMI in my case), each of them capable of up to 270 MHz pixel clock. That's just enough for 1920×2160, i.e. exactly half of 3840x2160, at 60 Hz when using custom CVT-RB v2 timings.

So if you have a "4K" monitor that can display two signals side by side ("Picture by Picture"), just hook up both DisplayPort and HDMI to it and then set both halves to that custom 1920×2160 60 Hz timing. Boom, you essentially get 3840×2160 at 60 Hz. And here it is:

(None of my "4K" monitors have PBP functionality so I had to quickly get my hands on one that does for this stunt LOL!)

This is, of course, old news - Bertha uses the same trick to increase the refresh rate to beyond what one single-link DVI output is capable of. Since this behaves like two separate monitors there's some drawbacks, i.e. the menu bar only extends across half the screen, the dock is off-center if set to appear on the bottom, full-screen windows don't span both halves etc. But 60 Hz is soooo much better than 30!



(No, I'm not done beating the crap out of the HD 3000 yet! )

 

[B S Magnet]

There's something else you can do with two outputs: combine them to smash the barriers of a single output

Starting point: The 2011 MBP cannot do 3840×2160 at 60 Hz. All it does is an utterly unusable 30 Hz. But... two daisy-chained Thunderbolt docks provide separate outputs (one DisplayPort, one HDMI), each of them capable of up to 270 MHz pixel clock. That's just enough for 1920×2160, i.e. exactly half of 3840x2160, at 60 Hz when using custom CVT-RB v2 timings.

So if you have a "4K" monitor that can display two signals side by side ("Picture by Picture"), just hook up both DisplayPort and HDMI to it and then set both halves to that custom 1920×2160 60 Hz timing. Boom, you essentially get 3840×2160 at 60 Hz. And here it is:

View attachment 1859209
(None of my "4K" monitors have PBP functionality so I had to quickly get my hands on one that does for this stunt LOL!)

View attachment 1859212
This is, of course, old news - Bertha uses the same trick to increase the refresh rate to beyond what one single-link DVI output is capable of. Since this behaves like two separate monitors there's some drawbacks, i.e. the menu bar only extends across half the screen, the dock is off-center if set to appear on the bottom, full-screen windows don't span both halves etc. But 60 Hz is soooo much better than 30!



(No, I'm not done beating the crap out of the HD 3000 yet! )

This… is just ludicrous. I mean that in the best possible sense.

What I need to do is prepare a list (for myself) of every display hack you’ve ever posted. That way, once I finally get around to procuring an actual DVI- or mini-display port-based display, then I’ll have a sense of all the unique, even peculiar ways which I can try to optimize screen real estate using the Macs I already have. (As opposed to, say, acquiring a fat stack of displays and GPUs and doing an Erik-styled command centre, as I lack both the desk space and work space presently to explore a multiple displays path — at least, any quantity beyond maybe two displays, tops.)

 

[Amethyst1]

This… is just ludicrous. I mean that in the best possible sense.

I know

What I need to do is prepare a list (for myself) of every display hack you’ve ever posted.

I've got one left that, if it works, will probably blow your mind.

 

[B S Magnet]

I know


I've got one left that, if it works, will probably blow your mind.

Welp, my 2015 MBP with the broken display is probably out, but I have that early 2011 13-inch MBP, identical to yours, which I feel deserves more screen real estate — either literally or virtually.

I had been looking at that inexpensive Thunderbolt adapter you posted recently which tricks the bus into thinking a max-size display is connected, so that accessing it with Remote Desktop or VNC will present a 2560x1600 remote display screen when in clamshell mode. But until I figure out how to do it with the lid up, yet still in a clamshell mode of sorts (with no external keyboard and mouse connected), I’m probably going to hold off (I want to keep things inside remaining cool). So it’s either that or I’ll just look for a cheap local used display. Then the challenge arises of where to put it in my work space.

So much to think about whilst I marvel at your discoveries…

 

[Amethyst1]

I had been looking at that inexpensive Thunderbolt adapter you posted recently which tricks the bus into thinking a max-size display is connected, so that accessing it with Remote Desktop or VNC will present a 2560x1600 remote display screen when in clamshell mode. But

That dummy display emulator will work irrespective of clamshell mode. It just tricks the computer into thinking there's a 2560×1600 display hooked up via DisplayPort. If you set this dummy display to be the main one and then connect remotely, you should get a 2560×1600 desktop. If you want to disable the MBP's internal screen without closing the lid, DisableMonitor claims to do the trick (but comes with a very scary warning). SwitchResX also claims to do the trick.

 

[B S Magnet]

That dummy display emulator will work irrespective of clamshell mode. It just tricks the computer into thinking there's a 2560×1600 display hooked up via DisplayPort. If you set this dummy display to be the main one and then connect remotely, you should get a 2560×1600 desktop. If you want to disable the MBP's internal screen without closing the lid, DisableMonitor claims to do the trick (but comes with a very scary warning). SwitchResX also claims to do the trick.

Thanks. I will look into this.

The DisableMonitor thing appears to be related to an issue (#82) in which it is probably not likely to be related to the code of this feature, and it also appears to have happened on a Thunderbolt 3-equipped Mac. There is always risk when doing hacks, but that’s part of the excitement, I suppose.

 

[joevt]

This is, of course, old news - Bertha uses the same trick to increase the refresh rate to beyond what one single-link DVI output is capable of. Since this behaves like two separate monitors there's some drawbacks, i.e. the menu bar only extends across half the screen, the dock is off-center if set to appear on the bottom, full-screen windows don't span both halves etc. But 60 Hz is soooo much better than 30!

Need to look into patching the driver to make it think the two inputs are for the same display by adding some tile info to the EDID. Not sure if the graphics drivers for the HD3000 supports tiled displays at all though. I don't think an EDID override is sufficient but I haven't tried it. I guess that the patch has to be done at a lower level (when the EDID is first read by the driver).

When did Apple begin support for 4K MST displays? Those were the first dual tile displays using two streams of a DisplayPort 1.2 connection. MST was introduced with DisplayPort 1.2 so I guess you need to look at the first Thunderbolt 2 Macs?

5K iMacs and the original LG UltraFine 5K and Dell UP2715K were the first dual link SST displays (dual tile displays using two separate DisplayPort connections).

 

[Amethyst1]

When did Apple begin support for 4K MST displays?

Presumably in 10.9.0, for the Asus PQ321 and Sharp PN-K321, on the 2013 Mac Pro.

5K iMacs and the original LG UltraFine 5K and Dell UP2715K were the first dual link SST displays

…and the HP z27q.

 

[joevt]

Presumably in 10.9.0, for the Asus PQ321 and Sharp PN-K321, on the 2013 Mac Pro.

…and the HP z27q.

Oh right. I should have looked in the Overrides folders.

/System/Library/Displays/Overrides started in 10.4 Tiger (well, for Intel Macs anyway; I don't have an earlier macOS on my MacPro3,1).
/System/Library/Displays/Contents/Resources/Overrides started in 10.11 El Capitan.

The first mtdd file was in 10.10 Yosemite for the Dell UP2715K.
The second mtdd file was in 10.11 El Capitan for the HP z27q.
The third mtdd file was in 10.12 Sierra for the first LG UltraFine 5K.
High Sierra 10.13 added the LG UltraWide 5K2K display.
Mojave 10.14.5 added the second LG UltraFine 5K.
Catalina 10.15 added a couple mtdd files for the XDR display (one for 5K only, and another for both 5K and 6K).

The mtdd files appear to exist only for the dual link SST displays. I'm not sure why there aren't any for the iMac 5K Retina displays which are also dual link SST displays.

I guess the 4K MST dual tile displays don't require an mtdd or an override so looking in the overrides folders won't help discover when support for those was added. It may be that info for those is hard coded in the drivers as implied by that AnandTech article. That AnandTech article says 10.9.3 is when support for arbitrary 4K MST dual tile displays was added (or at least more than the initial two white listed displays).

Sadly, Apple never got around to supporting arbitrary dual link SST displays such as my 4K144 display or the Dell UP3218K 8K60 display.

 

[Amethyst1]

/System/Library/Displays/Overrides started in 10.4 Tiger

It already exists in 10.2 Jaguar. I'm not sure about 10.0 Cheetah and 10.1 Puma.

Mojave 10.14.5 added the second LG UltraFine 5K.

So if you connected that monitor to a Mac running Sierra or High Sierra it wouldn't display properly?

I'm not sure why there aren't any for the iMac 5K Retina displays which are also dual link SST displays.

Maybe the tiling info is hard-coded?

I guess the 4K MST dual tile displays don't require an mtdd or an override so looking in the overrides folders won't help discover when support for those was added. It may be that info for those is hard coded in the drivers as implied by that AnandTech article. That AnandTech article says 10.9.3 is when support for arbitrary 4K MST dual tile displays was added (or at least more than the initial two white listed displays).

Fortunately, there's only a handful of tiled "4K" MST displays (Asus PQ321Q[E], Dell UP2414Q/UP3214Q, Sharp PN-K321[H] and some Panasonic TV AFAIK). It was a horrible kludge.

Sadly, Apple never got around to supporting arbitrary dual link SST displays such as my 4K144 display or the Dell UP3218K 8K60 display.

Or the Eizo FDH3601, or the IBM T221.