[Arm-netbook] OT: Food for thought

[David Niklas]

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On Fri, 5 Jul 2019 19:42:46 +0100
Luke Kenneth Casson Leighton <lkcl at lkcl.net> wrote:
> On Saturday, July 6, 2019, David Niklas <doark at mail.com> wrote:
> 
> > Dear luke, list,
> >
> > As both luke and I are interested in chip fabrication I'm dropping
> > this email with a link to a story on a SW tool that is designed to
> > help improve designs based on how exactly a foundries process works.
> >
> > Luke, the wording in this article looks very carefully chosen in
> > places. I'm totally in the dark as to why; e.g. "...the platform that
> > analyzes yields enables secure collaboration between the foundry and
> > customer."  
> 
> 
> The Foundries absolutely flatly refuse to trust their customers.
> 
> They flatly refuse to provide them with the "cells" for even basic
> things like "a transiator".
> 
> So the tools basically have to create a GDS file with "holes" in them,
> where things like "transistor" or "memory cell" or "IO Pad" go.
> 
> The f*ckers won't even give information about the *size* of those
> "holes", or how to connect to them, without an NDA.
> 
> However from what that article is *not* saying, even the "usual" NDA
> method is just not enough, at the lower geometries. For 20nm and
> bigger, things like MOSIS "rules" are perfectly sufficient. Lay out a
> design, no really special knowledge that hasn't been known
> (realistically) for 20+ years, no problem.
> 
> 10nm and below is a WHOLE new level of weird.
> 
> It looks like there are some quantum interferences as well as EM and RF
> issues, *and* probably some power and layout issues in the tinier
> geometries, all of which the Foundries absolutely do not want the
> customers to know about, because it constitues "reverse engineerable
> knowledge" about how the Foundry lays out the chips, and a competitor
> Foundry could get hold of that and start their own multi billion dollar
> money spinner.

Here's where closed source IP really confuses me: If a "money spinner"
tried to do that wouldn't they be sued, pay royalties and regret it for
the rest of their existences? Therefore, this "they understand the
science and specs of our implementation," paranoia is unfounded, right?

> So they did a deal with Synopsis, where they would tell *them* how to
> avoid those pitfalls, as long as Synopsis promised to hide the
> information in such a way that, whilst the customer got the layout
> advice they need to get a working ASIC, they would in no way be able to
> know *how* that ASIC actually got manufactured.
> 
> This is of course all inferred guesswork. Welcome to my world of low
> probability logical deduction aka reverse engineering.
> 
> Bottom line is, we're literally decades and hundreds of millions of
> dollars away from libre foundries.  I am probably out on those
> estimates by 1 to 2 orders of magnitude. 

Are we talking any libre foundry, or some particular nm size (not that a
nm is actually used to describe a nm anymore)?

> Luckily, DARPA recognises the problem and put up USD 150m to create
> fully libre automated ASIC layout software. It's a start.

Interesting. For posterity, here's a link (with HTML garbage removed):
https://www.fbo.gov/index?id=a32e37cfad63edcba7cfd5d997422d93

Though it looks to be pre-alpha.

> In the meantime I am tracking what lip6.fr are doing (the team behind
> alliance / coriolis2). They will be doing a 40nm tapeout using FreePDK,
> ported to their cell library system.

I was able to locate the coriolis2 docs here:
https://www-soc.lip6.fr/sesi-docs/coriolis2-docs/coriolis2/en/html/users-guide/UsersGuide.html
and the alliance project has a web page with installation instructions
here:
https://www-soc.lip6.fr/equipe-cian/logiciels/alliance/

It's all very interesting.

> Once successful it will be possible to follow in their footsteps and do
> a 40nm Libre RISCV tapeout.
>
> The layout software produces *linearly* scaleable designs, so
> hypothetically, as long as RF EM is ok (on chip) scaling to 28nm should
> be feasible.  Just not straight away.
> 
> L.

Yay!

Thanks for the info,
David
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