IBM's PPC being open sourced .. what does this mean for embedded devices ?

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HI all,


I know is this kind-of old news by now, but -as far as I see- this has  
not been discussed here:

IBM is open-sourcing their PowerPC processor design.

(E.g. see here and other links:)
https://www.eejournal.com/article/ibm-gives-away-powerpc-goes-open-source /)


As PowerPC processors do are used in embedded devices, anybody any idea  
what this would mean for the embedded-processor market?
Are we now going to be flooded by Chinese ppc-based devboards?
And is this going to kill the risc-v?



BTW.
Does anybody have an easy-to-use overview of different powerPC  
architectures out there? (especially for embedded use)

I've been trying to understand the different wikipedia pages on the  
powerPC architectures, but it all seams to one giant mix of names,  
numbers and 'books' from a dozen different companies.



Cheerio!
Kr. Bonne,

Re: IBM's PPC being open sourced .. what does this mean for embedded devices ?
On 9/16/2019 21:36, kristoff wrote:
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If someone takes on and starts making more power architecture processors
the impact could be huge, this is by far the best architecture I have
seen in my life - and I have explored most of them (and used power for
decades now).
Then it might make no impact at all, how many of those making decisions
of such magnitude can see further than the next quarter report and
can look into something other than what "everybody is doing".

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The only maker of Power architecture processors is NXP (since they
acquired Freescale). IBM had an embedded core some ages ago, 401
or something like that, which some other company - AMCC I think - took
on but I never used any of these.

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Thanks for posting, I had missed the news so this is new to me.
Good news I suppose, gives some hope that this great architecture
will survive after all.

Hopefully I can migrate DPS to 64 bit power sooner rather than
later, I have been wanting to do it for quite some time now. Might also
be some help.

Dimiter

======================================================
Dimiter Popoff, TGI             http://www.tgi-sci.com
======================================================
http://www.flickr.com/photos/didi_tgi/






Re: IBM's PPC being open sourced .. what does this mean for embedded devices ?
On Monday, September 16, 2019 at 4:24:40 PM UTC-4, Dimiter wrote:
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Maybe I'm not remembering it right, but I thought the PPC fell out of favor
 because as processors got faster and more complex, the PPC architecture lo
st it's advantages.  I would seem I am not remembering this correctly.  

So why did the PPC architecture stop being developed?  Is this still a comp
etitive architecture in general?  I'm guessing it is still competitive in l
ower end processors for sure.  How does it stack up to MIPS?  Isn't that on
e also open source?  Or was that open sourced only in a very limited way?
  

--  

  Rick C.

  - Get 2,000 miles of free Supercharging
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Re: IBM's PPC being open sourced .. what does this mean for embedded devices ?
On 9/17/2019 5:11, Rick C wrote:
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The architecture did not lose its advantages, it is just as silicon got
faster messy designs like the x86 could run fast enough for the general
population.

I don't know how far did IBM go developing it, may be they still do.
I know only the Motorola/Freescale line, some of which I have used and
am using. Their latest designs are 64 bits QORIQ (someone got away
without being punished for that name) which look quite good really.

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MIPS looks like a smaller scale power, I have not used it, just looked
at it. No idea if it is open source. Microchip make some 32 bit MCU-s
with MIPS, I have not heard people using them complain.

Dimiter



Re: IBM's PPC being open sourced .. what does this mean for embedded devices ?
On Tuesday, September 17, 2019 at 12:11:05 AM UTC-4, Dimiter wrote:
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avor because as processors got faster and more complex, the PPC architectur
e lost it's advantages.  I would seem I am not remembering this correctly.
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There has to be some reason why they lost the war other than marketing.  Ap
ple was using the PPC and many others.  So there was clearly a market.  Per
haps I didn't state things correctly.  The advantages of the PPC must not h
ave been significant enough in larger chips to make continued development o
f ever more expensive designs worthwhile.  I recall when IBM dropped out of
 the race.  They must have seen the handwriting on the wall.  

So how does Freescale keep paying for spins on 64 bit chips?  I take it the
y still can hold a match to the Intel processors, rather they are now compe
ting with the ARMs of the world?  


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competitive architecture in general?  I'm guessing it is still competitive  
in lower end processors for sure.  How does it stack up to MIPS?  Isn't tha
t one also open source?  Or was that open sourced only in a very limited wa
y?
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Yeah, seems the open source thing is real...  They seem to be saying MIPS h
as some real advantages over RISC-V but they may not last...  

"While RISC-V is gaining grown[sic] the storied history of MIPS means that  
the MIPS stack is far more complete, and includes things like DSP and SIMD  
extensions that still don?t exist for the RISC-V platform."

I've read here that most MIPS designs are embedded cores in custom ASICs.  
So someone already loves them.  Seems the current owners of the MIPS archit
ecture think open sourcing the design will allow them to sell more IP solut
ions.  

--  

  Rick C.

  + Get 2,000 miles of free Supercharging
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Re: IBM's PPC being open sourced .. what does this mean for embedded devices ?
On 17/09/2019 06:26, Rick C wrote:
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There are others that have made PPC based devices in the past.  But I
think NXP is the only company making microcontrollers and network
processors based on PPC in any serious way.  ST has (last time I looked,
which was a while ago) second-source copies of a number of NXP PPC
microcontrollers, but I don't think they had any of their own.

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The key change, I think, was the move from x86 cores that ran x86 code,
to x86 processors that translated x86 instructions into an internal RISC
code that is executed on a RISC core.  RISC designs and load-store
architectures with lots of registers are much better suited to fast
execution, pipelining, OoO execution, and super-scaling than CISC ISAs.
 Once x86 cpus started using RISC cores internally, much of the
advantage of PPC is lost in comparison.

And x86 has several advantages that PPC can't get, beyond the obvious
compatibility with x86 binaries.  One is the x86 strong memory model -
it is a good deal simpler for programmers than weaker memory model of
most RISC designs, and a lot of code is written with the assumption of a
strong memory model.  The PPC exposes the guts of its RISC core to the
programmer - and thus cannot easily change it - with x86 cpus, their
RISC cores are hidden and designers can change it as they want for each
new chip.  They can have 37-bit wide instructions, completely re-arrange
the encoding, add hundreds of registers, etc., whereas PPC designers
have to stick to the ISA.

Of course, PPC implementers could move in this direction too - turning
PPC RISC instructions into an expanded internal RISC design for
execution.  I think the size of the ISA might make that harder than for
the x86, and it won't solve the memory model challenge, but it could
work.  But they haven't had the same motivation - they haven't hit the
same performance brick wall as the x86 world faced.

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No, there doesn't.  IBM have demonstrated in the past that they are
capable of technical excellence combined with extraordinary screw-ups by
sales, marketing, purchasing and licensing departments that don't
understand the products, and don't talk to each other.  The whole sad
OS/2 story is an example.

That doesn't mean there /aren't/ other reasons, merely that
non-technical reasons can be enough.

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Certainly keeping in the race was getting more and more expensive.
Intel could use their server chip money to pay for it, but IBM did not
have high-margin PPC customers (there Power cpu line for big iron is
separate) screaming for faster cores.

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They don't.  No PowerPC devices come close to top Intel/AMD processors.
 And for the devices NXP make, the core speed is not critical.  NXP make
two types of PPC devices - automotive / high-reliability devices (up to
about 300 MHz core speed), and networking (up to 1.5 GHz core).  For the
automotive devices, reliability, robustness and peripherals are key, not
the core or the core speed.  For the networking devices, it is the
networking hardware that is key - the core is for control, not for
processing.  AFAIK all NXP's PPC chips are 32-bit.


There is often a confusion between "Power" and "PowerPC".  It doesn't
help that NXP talks about their "Power" devices when they mean "PowerPC".

The "Power" architecture is IBM's big iron chip, and these are big,
fast, expensive, power-hungry, and full of big iron features like
redundancy, hot-plugging (for memory, cores, etc.).  They are made by
IBM, and they run the many of the top supercomputers as well as every
bank in the world.

"PowerPC" was an initiative started by IBM, Apple and Motorola - taking
the basic ISA from the Power world, removing all the "big" features, and
making something that could be implemented in a single chip that was
competitive in size, speed and cost with the x86's and 68k devices of
the time, but with a scalable future.

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If you haven't heard them complain, you haven't heard me :-)  My
complaint with Microchip's MIPS microcontrollers is that they used a
poor choice of core (MIPS had more appropriate ones at the time),
screwed up the chip (it was to be the first microcontroller with USB 2
on the device, but it only worked at USB 1.1 speeds), crippled the
compiler (optimisation was disabled unless you paid a large license fee,
meaning people got the impression that the core was slow), and called it
"PIC32" so that people thought MIPS cores were as brain-dead as a PIC.
In my mind, Microchip and the PIC32 are the key reason we don't have a
range of manufacturers making MIPS microcontrollers - as there are MIPS
cores that are equivalent or better than ARM cores across the range of
sizes and powers.

In terms of architecture, MIPS has a different background from PowerPC
(or Power before it), but there is definitely a strong similarity.

MIPS is not open source, but easily licensable at different levels and
for different cores.  I think you can use the ISA in your own designs
without a license (there are some Chinese MIPS ISA cores).  You can do
that with SPARC too, if anyone but Fujitsu cares.

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Re: IBM's PPC being open sourced .. what does this mean for embedded devices ?
On 9/17/2019 11:58, David Brown wrote:
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Well emulating a processor on another - like Intel do - is nothing
particularly new, I myself have emulated the 6809 on power under dps
(had some code written in the mid 80-s which I still can - and do -
use).
However no matter how efficient your emulation is it is an emulation
and has its performance cost. Under equal circumstances power can
beat Intel hands down. No such comparison can be made though,
if you compare this or that piece of C software you will compare
a compiler to another rather than a core to another - so Intel
will likely win simply because of its huge popularity, the man
hours put into compilers for x86 must outdwarf these put into
power compilers.
So a performance comparison just cannot be done in a decent way.

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At the point where Apple abandoned PPC and went Intel what I remember
was Jobs saying Freescale (or wast it still Motorola SPS) or IBM or
both could not deliver the silicon they wanted, i.e. it was a production
complaint. I am not sure I buy into that, I have my conspiracy theory
about what happened but well, it is just a theory of mine, I can't
prove it and it might well be wrong on top of that.

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Oh no, they have 64 bits for years now. Just check the website, they
have up to 8 physical cores and 16 logical ones (or was it 4/8),
just look for QORIQ power. Really powerful beasts they are, GHz
range, 750 MHz clocked DDR4 etc., that on a SoC.

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PowerPC (PPC) was dropped some 10 years ago as a name, it is called
"Power Architecure" nowadays. Not to be confused with IBM's Power
from the 80s, which is sort of the same but not quite, this is where
the architecture originated (the guy who did it has been really good).
Of course people use PPC and power interchangeably nowadays so unless
you are intimate with what is on offer it can be a source of confusion.

Dimiter

======================================================
Dimiter Popoff, TGI             http://www.tgi-sci.com
======================================================
http://www.flickr.com/photos/didi_tgi/

Re: IBM's PPC being open sourced .. what does this mean for embedded devices ?
Hi Rick, all,

First, thanks to all for replying and taking up this thread. This is  
very interesting.


On 17/09/19 04:11, Rick C wrote:
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I wasn't aware that MIPS ISA has been open-sourced. According wikipedia,  
the descision to open-source was taken in 2018, to be executed in 2019.

https://www.mipsopen.com/


Note that they just call it "open" and "open use", not open-source and  
-as far as I see it- it is not open source.
E.g. the license agreement states that the technology (including the  
ISA) is still subject to US export-control, which makes the license  
incompatible with any open-source license.
It looks more like 'freeware' then 'open source'.

Note that their website also mentions two cores: the microAptiv UP and  
UC cores.


This makes them much less open then (say) risc-v or the opensparc licenses.


Kristoff



Re: IBM's PPC being open sourced .. what does this mean for embedded devices ?
On 16/09/2019 20:36, kristoff wrote:
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No, they are not (as far as I understand the situation).  The linked
article seems a bit mixed up as to what they are giving away (they are
mixed up about RISC-V too).

When talking about processor licensing, there are many levels.  You can
license the ISA - the instructions, register setup, instruction codings,
etc.  This is the minimum you need in order to make a cpu that will run
binaries for that processor.  You can license design files (Verlig,
VHDL, etc.) for some or all of an implementation.  You can license hard
macros for some or all of an implementation.  You can license the right
to use names, trademarks, patents, etc.  You can license the right to
modify and expand on any of this.

As far as I know, IBM has offered commercial licenses on all of these
bits - just as ARM, MIPS, etc. do.  Some customers have taken the ISA
and made their own implementations, others have taken complete hard
macros and put them on ASICs, others go somewhere in between.

From this article, it seems IBM is giving free licensing for the ISA.
That means you can make your own processor in an FPGA, ASIC, etc., that
runs PowerPC code.  It is not clear how open it is - do you need to
obtain a zero-cost license?  Can you modify the ISA as you want?  What
about naming - can you call it a PowerPC processor or PPC compatible,
even if you add things to it?  What about if you remove features?  Will
groups other than IBM, Apple and NXP be involved in the future of
PowerPC and its ISA?

It does not appear that they are giving away a usable /implementation/
of a PowerPC core.

I'm guessing answers to all these points are to be found with a bit of
research on the Linux Foundation or IBM's websites, but they need
considered before it is clear what IBM have actually done here.


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Mostly nothing, I think.

PPC cores are used in a few specific embedded markets - primarily the
automotive industry, and other tough industrial uses.  They used to be
popular in networking systems (along with MIPS), but ARM is taking over
that niche.  I think you will continue to get PPC-based devices from
those that made them before (primarily NXP, with some second-source
devices from ST).  I don't think anyone is going to design a new
implementation for new devices unless they are already invested in the
PPC world.  PPC simply does not have any advantages over alternatives,
and it is a big and heavy ISA compared to RISC-V.

What you might see is a few more second-source parts, perhaps also
things like radiation-hard or high-temperature versions from folks like
Atmel.  And you might see it in use in systems that need a very fast
processor and are willing to spend a lot of effort to get it, but want
low production or licensing costs - maybe we'll see it again in games
consoles, or chips designed specifically for supercomputers.

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No, it won't kill RISC-V.  It will (in my humble and only somewhat
informed opinion) aid RISC-V, by making "open source ISA" more
acceptable to conservative and sceptical companies who viewed "open
source ISA" as meaning "made by hobby developers" or "made by
communists".  When IBM says "open source ISAs are good", they are more
likely to take note of other open source ISAs.

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I'd be surprised if such a thing exists.  There are /many/ PPC variations.

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