[svlug] j-core vs RISC-V

[Rick Moen]

Quoting Ivan Sergio Borgonovo (mail at webthatworks.it):

> I've read the j-core home more carefully and I got j-core is not only 
> inspired but is compatible with SuperH.

The j-core project's first goal was a SoC called J2 and then an
expansion of that called J2+, both being clean-room compatible
reimplementations of the Renasas (ex-Hitachi) SuperH SH2 RISC core.
(The SH2 was used, oddly enough, in Sega's Saturn game console, among
other things.)  When j-core was launched two years ago, the requisite
SuperH support in the Linux kernel, etc. was a little moldy but still
usable with a bit of maintenance work.  

Right around this year, also, the last of the SuperH SH4 patents should
be expiring, so doubtless the follow-on to J2 and J2+ will be even more
interesting.

I'm pretty sure I cited the LWN.net coverage in this space at the time,
but here it is again:
https://lwn.net/Articles/647636/

> Do you think there is any chance to see large deployment of Linux on a 
> new architecture?

You asked that of Rob, not me, but here's my take on that:

There's always been room in Linux space for non-mass-market interests.
It's just a matter of a modest investment of money, like initial design
and batch-production runs of open-design SoCs, and significant
commitments of ongoing time and care.  The mass market doesn't care
about security, doesn't give a tinker's damn about (e.g.) multiple ring
-2 subsystems underlying all of our computing systems ripe for takeover
by not just state-actor spook agencies but criminal gangs and (pretty
soon) your corner bookie.  The mass market by and large doesn't even
deal in computers at all; increasingly, it just buys capacity from EC2
or somebody's OpenStack cluster on an oursourced basis, and neither
knows nor cares what it run on.

And I'm fine with that for the purpose of my making money off those
people, because their cash is green (USA, land of funny-looking green
currency) and I get to take some of it home.  But for my own computing,
where I'd rather not be supporting someone else's undetectable rootkit, 
I have a problem with black box hardware subsystems and would rather
move sideways to either not have them present or have them provably
disabled.

For my purposes, any hardware effort that can deliver that within
reasonable pricing is highly attractive irrespective of whether it ever
sees 'large deployment' -- and such an effort might well remain healthy
and maintained over medium (5-10 year) periods without large market
success ever being necessary.

Specifically the J2, J2+, and projected SH4-based follow-on strike me as
a notable exception to the general rule that 'embedded' Linux devices
have to date inevitably had hideously proprietary major subsystems and 
usually also proprietary-software dependencies.  I see in (finally)
skim-reading basic materials about U.C. Berkeley's RISC-V project, that
(as you said upthread) it intentionally supports both open and
proprietary implementations, so one would have to look into the
particulars of any specific RISC-V-based offering.  I have to say, my
expectations in that department are low, because the entire history of
embedded computing has leaned proprietary, for reasons amply discussed
on this mailing list and elsewhere (cheap, mostly outsourced
development, very short product cycles).  If you hear about a RISC-V
implementation that _is_ open in a comprehensive 'turtles all the way
down'[1] fashion, please do call attention to it -- but I'll not be
holding my breath waiting for it.


[1] Reference is to an old anecdote repeated for many decades among 
scientists but of uncertain origin, appearing in such places as Stephen
Hawking's _A Brief History of Time_:

  A well-known scientist (some say it was Bertrand Russell) once gave a
  public lecture on astronomy.  He described how the earth orbits around
  the sun and how the sun, in turn, orbits around the center of a vast
  collection of stars called our galaxy.  At the end of the lecture, a
  little old lady at the back of the room got up and said:  "What you have
  told us is rubbish.  The world is really a flat plate supported on the
  back of a giant tortoise."  The scientist gave a superior smile before
  replying, "What is the tortoise standing on?"  "You're very clever, young
  man, very clever," said the old lady.  "But it's turtles all the way
  down!"

-- 
Rick Moen         There was an old man             Said with a laugh, "I 
rick at linuxmafia   From Peru, whose lim'ricks all   Cut them in half, the pay is 
           .com   Looked like haiku.  He           Much better for two." 
McQ!  (4x80)                                            --Emmet O'Brien