Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

M1 Thunderbolt ports don’t fully support USB 3.1 Gen 2

eclecticlight.co

Post reply on HN
Print view View original

111–120 of 333 posts

Re: M1 Thunderbolt ports don’t fully support USB 3.1 Gen 2

#111

Post by matja »

amelius wrote: post #60
masklinn wrote: post #41

Earlier quoted context omitted.

FWIW it's actually 500MB theoretical (ideal), because USB uses a 8/10 encoding[0], until 3.1 Gen 2 which switches to a 128/132 encoding[1]. So you have a 5Gb/s physical signal, then a 25% encoding overhead, for a raw data throughput of 537MB/s. Once framing and protocol overhead are taken in account, mid-400s effective is probably a good result. [0] https://en.wikipedia.org/wiki/8b/10b_encoding [1] https://en.wikiped…

What sucks, however, is that you can transfer 1TB to a USB drive correctly, and then finally have a bit-error that spoils the entire transfer and might even corrupt your drive. Happened to me several times during testing on different machines and with different cables and drives (luckily no real data was lost, but USB is now sort of banned from my office for use with external harddrives). Any sane protocol would be a…

Use a filesystem that does end-to-end error detection and correction. I use ZFS on all of my USB drives (even "real" SATA and M.2 SSDs via adaptors) and it frequently finds checksum errors (and thanks to the design of ZFS, is able to completely recover without any risk of further corruption).

Re: M1 Thunderbolt ports don’t fully support USB 3.1 Gen 2

#112

Post by efficax »

superkuh wrote: post #89

Quoted post unavailable.

> Even software that is directly ported has trouble because M1 tile memory cache is designed for minimal tasks, not heavy computing, and computationally heavy software has to be re-written from scratch to optimize it for the platform.

Huh? I have no idea what this is supposed to mean. Tile based memory refers to the GPU, and you don't have to rewrite your GPU software from scratch, that's insane? That's what Metal is for. Whatever this is supposed to mean I'm pretty sure it's not even wrong

Re: M1 Thunderbolt ports don’t fully support USB 3.1 Gen 2

#113

Post by notatoad »

grishka wrote: post #48
masklinn wrote: post #29

Earlier quoted context omitted.

> what in the world could "USB 3.1 Gen 2" possibly mean? Versions are free, why not simply name it "USB 3.2" and make the next one 3.3? USB 3.1 Gen 1 is the straight rebranding of USB 3.0, USB 3.1 Gen 2 is the "original" 3.1, which is 3.0 updated to a 10Gbps signalling rate (from 5), and a more efficient encoding (128/132, versus 8/10). But wait, there's worse! USB 3.2 Gen 1 is the same thing as USB 3.1 Gen 1 USB 3.2…

> USB 3.1 Gen 1 is the straight rebranding of USB 3.0 Why? To solve what exactly? In a sane world, it'd be major.minor, with nothing appended at the end. Allowing marketers to take over everything was such a terrible mistake. At this point I myself just don't differentiate USB versions beyond 3.0. 2.0 is the slow one, 3.0 is the fast one, anything newer is "so fast I won't ever saturate this much bandwidth anyway". T…

IIRC, USB 3.1 was an update to the spec to allow USB Type C connectors. USB 3.0 specified the old type-a connector on one end and one of the weird oversized type-b connectors on the other end.

Maybe not relevant as a consumer to have a difference in the spec version for that, but if you’re a manufacturer trying to implement it, it’s worth a bump to the minor version number.

Re: M1 Thunderbolt ports don’t fully support USB 3.1 Gen 2

#114

Post by harha »

matja wrote: post #109
ramijames wrote: post #81

The fact that I can't connect more than one monitor to my M1-based iMac is a fucking travesty.

Were you expecting to be able? The tech specs say "One external display".

Not sure this is fair to the consumer. Apple was advertising usb-c as one port to rule then all. When the device has two of these ports, why should the user expect not to connect two displays?

Especially since this restriction didn’t apply to the previous models that looked exactly the same and are now advertised as less powerful.

It would be natural to not explicitly look for how many displays it can handle.

Re: M1 Thunderbolt ports don’t fully support USB 3.1 Gen 2

#115

Post by chrisfinazzo »

bombcar wrote: post #95
ChuckNorris89 wrote: post #85

Earlier quoted context omitted.

May I ask why? I assume you were aware of this limitation, as Apple was pretty clear in the specs about it, that it only supports one external monitor. If you pull the trigger on a purchase without reading the specs, then it's pretty much on you, no?

It didn’t become widely known until after the M1s had shipped - I was caught unexpected after someone at work couldn’t connect two to theirs.

Pretty much this. At the moment, I am trying to sort this out for my parents who bought a MacBook Air to replace a 12" MacBook and want to know if it is still possible to use a pair of 23" 1080p HP displays with it.

They don't care about resolution so much, nor does my brother who tested this setup with his 2017 MacBook - bad keyboard and all.

(On that front, last I heard, there was a hidden preference for non-HiDPI displays which has been completely removed, causing some issues.)

So far as I can tell, it is possible to run more than 1 display on the M1 - but it requires using a version of the DisplayLink driver with some extra [hardware][1], which is not exactly straightforward and I question how well this works in practice.

Sonnett is not the only one doing this, but it's the first one I found.

[1]: https://www.sonnettech.com/product/m1-mac-dual-displayport-a...

Re: M1 Thunderbolt ports don’t fully support USB 3.1 Gen 2

#116

Post by mmastrac »

I find it amusing that every single one of our high-speed standards (ethernet, HDMI, PCIE, displayport, USB) are basically just the same high-speed differential pairs under the hood with different framing.

I don't know exactly what we can do about this situation, but at some point it probably makes sense for all of them to converge into a multi-lane, differential-pair standard (or just support nesting each other arbitrarily).

Re: M1 Thunderbolt ports don’t fully support USB 3.1 Gen 2

#117

Post by eddieroger »

ramijames wrote: post #81

The fact that I can't connect more than one monitor to my M1-based iMac is a fucking travesty.

It must be to have posted the same comment twice.

Did you do any research in to it before buying it? Apple was never misleading about how many monitors it could support. The "Tech Specs" product page says it can power its internal display and one extra external one. Just because you want it to do something doesn't make it a travesty when it can't.

Re: M1 Thunderbolt ports don’t fully support USB 3.1 Gen 2

#118

Post by rowanG077 »

jsjohnst wrote: post #76
scoopertrooper wrote: post #72

Earlier quoted context omitted.

Quoted post unavailable.

Just because it works on an Intel Mac does not mean the cable isn’t the issue! Happy to demonstrate in a live video along with oscilloscope readings to prove it is in fact the cable to blame.

I would like to see this. Mostly to see what kind of an absolute beast of an oscilloscope can keep up with the data rate.

Also I don't understand why people are disagreeing with you. If a cable is not within spec it's absolutely possible for it to work in one circumstance because for example the port is more lenient and completely fail with a port that is more strict.

Re: M1 Thunderbolt ports don’t fully support USB 3.1 Gen 2

#119

Post by vmception »

woodruffw wrote: post #5

The inability of the USB standards body to stick to a versioning scheme beggars belief: what in the world could "USB 3.1 Gen 2" possibly mean? Versions are free, why not simply name it "USB 3.2" and make the next one 3.3? "Gen 2" strikes me as the "Essay FINAL (final version 2).docx" of standards revisions.

The Final Season, Part 3

Re: M1 Thunderbolt ports don’t fully support USB 3.1 Gen 2

#120

Post by bombcar »

chrisfinazzo wrote: post #115
bombcar wrote: post #95

Earlier quoted context omitted.

It didn’t become widely known until after the M1s had shipped - I was caught unexpected after someone at work couldn’t connect two to theirs.

Pretty much this. At the moment, I am trying to sort this out for my parents who bought a MacBook Air to replace a 12" MacBook and want to know if it is still possible to use a pair of 23" 1080p HP displays with it. They don't care about resolution so much, nor does my brother who tested this setup with his 2017 MacBook - bad keyboard and all. (On that front, last I heard, there was a hidden preference for non-HiDPI…

At least one person at work is using something like that to drive two displays from the M1, so I suspect it can be made to work well enough.
Post reply on HN