AMD Tackles Coming “Chiplet” Revolution With New Chip Network Scheme

Re:AMD Tackles Coming “Chiplet” Revolution With New Chip Net... by paulmd on Sunday June 24, 2018 @04:44PM (#17388297)

> The advantage for AMD is that they've built a single design: the Zeppelin die. RyZen is simply one Zeppelin. Threadripper is two Zeppelins. And EPYC is four Zeppelins.

While a popular meme, this is not actually true. Epyc is actually a totally different die, stepping B2 vs the B1 die used in Ryzen+TR.

https://en.wikichip.org/wiki/amd/ryzen_7/1800x

https://en.wikichip.org/wiki/amd/epyc/7601

The 2700X is actually on a different die as well, and Raven Ridge on another. There will probably be another die for Banded Kestrel, if AMD ever gets around to releasing that. Presumably, their embedded SOC products are their own die as well.

So, about 5 dies per generation, across AMD's lineup (Epyc, Ryzen, APU, Atom, and embedded SOC). They're using about half as many dies as Intel is - still a significant difference, but far from the "one die for the whole lineup!" meme.

The big difference is that they're serving the whole server market with one small die, vs the three that Intel uses.

Of course, a small die isn't all roses either - both mfrs limit you to 8 dies per system, so right now with an 8-core die AMD systems are limited to 64-core systems (dual-socket Epyc) versus the 224-core systems that you can do with octo-socket 28-core Xeons. But, not everybody needs a million-dollar octo-socket system either.

Once AMD takes a node advantage that advantage will be diminished somewhat, but Intel's 10nm woes are a whole different story ;)

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Re:AMD Tackles Coming “Chiplet” Revolution With New Chip Net... by st26 on Sunday June 24, 2018 @09:06PM (#17389268)

Steppings are minor revisions, perhaps analogous to a kernel patch revision. So they do have to manufacture B2 die and B1 die and they are not interchangeable- but they are 99.999% identical.

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Re:AMD Tackles Coming “Chiplet” Revolution With New Chip Net... by paulmd on Sunday June 24, 2018 @11:24PM (#17389713)

It still means these dies have to be fabbed and binned separately. Epyc and Ryzen are different dies and not interchangeable, they are not "the same die used across the whole lineup".

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Re:AMD Tackles Coming “Chiplet” Revolution With New Chip Net... by pocak on Monday June 25, 2018 @08:46AM (#17391947)

Are newer Ryzen 1000 series CPUs still made with the B1 die?

I thought steppings were for fixing errata, and once a new revision is qualified, the old one is no longer manufactured.

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Re:AMD Tackles Coming “Chiplet” Revolution With New Chip Net... by paulmd on Monday June 25, 2018 @06:47PM (#17396484)

All the Ryzen 1000 processors (including TR) were B1, at least as far as AMD told the USB-IF (and AFAIK nobody ever observed anything else in the wild). Epyc is on B2.

At the time, there was some speculation that B2 might be the "mirror image" die that Epyc uses 2 of.

http://www.usb.org/kcompliance/view/catalog_search/results_b...

http://www.usb.org/kcompliance/view/view_item?item_key=88142...

However, they now report Pinnacle Ridge (Ryzen 2000) as being on the B2 stepping.

Ryzen 2000 is on a slightly updated 12nm process but does not incorporate any library changes. I'm not sure if you could just drop the existing die onto the new process (given that 12nm is really a 14+), or if you could un-flip the die to the proper pinout using the substrate, but it seems like that might be where they moved to the B2 stepping.

But yeah, AMD produced the B1 stepping for an uncommonly long time. At least through the end of 2017, and the first B2 steppings showed up like June 2017.

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