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That's typical of open-source projects: functionality is fun; good
documentation is at least as time-consuming as good code (HDL or
software), and documentation-writing isn't nearly as fun.
For cutting-edge open-source stuff the key to success is to find the
web forum or mailing list that covers the subject, and to start asking
questions. I suppose that if I won the lottery and didn't get seduced
by Tahiti I'd pick a project and just write documentation.
I suppose this is one reason that Octave works so well for me: when I
have a question, I consult the Matlab documentation. That makes feel a
little guilty. I've found Octave is actually faster on a lot of my
scripts though.
Sadly, when you mentioned Tahiti, I was trying to figure out if that was
the name of some obscure HDL or open-source project. It took me a
minute to figure out you meant the place where Gaugin hung out. Yeah,
that might be better than writing documentation.
I don't know how small the RISC-V can be made. I know there is a
version designed in an ASIC that can compete with the ARM CPUs and there
are more than one version for FPGAs. I would hope they had a version
similar to the ARM CM-1 which is specifically targeted to programmable
logic and not overly large.
I don't know how small the RISC-V can be made. I know there is a
version designed in an ASIC that can compete with the ARM CPUs and
there are more than one version for FPGAs. I would hope they had a
version similar to the ARM CM-1 which is specifically targeted to
programmable logic and not overly large.
Speaking of ARM, I still can't figure out how ARM was acquired for $32B.
If even a student can make a synthesizable 32-bit processor in a few
weeks, how much value can there be in a processor? It's almost a
commodity. I know there is a lot of value in prediction pipelines,
cache logic, compilers, etc., but not $32b' worth.
On Mon, 01 May 2017 16:07:02 -0700, Kevin Neilson wrote:
I don't know how small the RISC-V can be made. I know there is a
version designed in an ASIC that can compete with the ARM CPUs and
there are more than one version for FPGAs. I would hope they had a
version similar to the ARM CM-1 which is specifically targeted to
programmable logic and not overly large.
Speaking of ARM, I still can't figure out how ARM was acquired for $32B.
If even a student can make a synthesizable 32-bit processor in a few
weeks, how much value can there be in a processor? It's almost a
commodity. I know there is a lot of value in prediction pipelines,
cache logic, compilers, etc., but not $32b' worth.
So, maybe the people who SOLD it are laughing their way to the bank.
ARM processor variants have a huge installed base -- I suspect that went
a long way to justifying the $32B. But, if ST started offering parts
with the RISC-V core tomorrow, at a better price, I'd switch.
I don't know how small the RISC-V can be made. I know there is a
version designed in an ASIC that can compete with the ARM CPUs and there
are more than one version for FPGAs. I would hope they had a version
similar to the ARM CM-1 which is specifically targeted to programmable
logic and not overly large.
Speaking of ARM, I still can't figure out how ARM was acquired for $32B. If even a student can make a synthesizable 32-bit processor in a few weeks, how much value can there be in a processor? It's almost a commodity. I know there is a lot of value in prediction pipelines, cache logic, compilers, etc., but not $32b' worth.
On 05/01/2017 04:46 PM, Tim Wescott wrote:
On Mon, 01 May 2017 16:07:02 -0700, Kevin Neilson wrote:
I don't know how small the RISC-V can be made. I know there is a
version designed in an ASIC that can compete with the ARM CPUs and
there are more than one version for FPGAs. I would hope they had a
version similar to the ARM CM-1 which is specifically targeted to
programmable logic and not overly large.
Speaking of ARM, I still can't figure out how ARM was acquired for
$32B.
If even a student can make a synthesizable 32-bit processor in a few
weeks, how much value can there be in a processor? It's almost a
commodity. I know there is a lot of value in prediction pipelines,
cache logic, compilers, etc., but not $32b' worth.
So, maybe the people who SOLD it are laughing their way to the bank.
ARM processor variants have a huge installed base -- I suspect that
went a long way to justifying the $32B. But, if ST started offering
parts with the RISC-V core tomorrow, at a better price, I'd switch.
You would. I probably wouldn't, having a larger team to drag around and
all of the associated infrastructure.
But the cell phone companies, with all that already written codebase and
10s of millions of units sold per year? Not a chance they do. That's
billions of dollars of inertia.
Pretty small (and fast):
https://forums.xilinx.com/t5/Xcell-Daily-Blog/1680-open-source-ISA-RISC-V-processor-cores-run-on-one-Virtex/ba-p/742731
I don't know how small the RISC-V can be made. I know there is a
version designed in an ASIC that can compete with the ARM CPUs and there
are more than one version for FPGAs. I would hope they had a version
similar to the ARM CM-1 which is specifically targeted to programmable
logic and not overly large.
Speaking of ARM, I still can't figure out how ARM was acquired for $32B. If even a student can make a synthesizable 32-bit processor in a few weeks, how much value can there be in a processor? It's almost a commodity. I know there is a lot of value in prediction pipelines, cache logic, compilers, etc., but not $32b' worth.
On Mon, 01 May 2017 17:15:01 -0700, Rob Gaddi wrote:
On 05/01/2017 04:46 PM, Tim Wescott wrote:
On Mon, 01 May 2017 16:07:02 -0700, Kevin Neilson wrote:
I don't know how small the RISC-V can be made. I know there is a
version designed in an ASIC that can compete with the ARM CPUs and
there are more than one version for FPGAs. I would hope they had a
version similar to the ARM CM-1 which is specifically targeted to
programmable logic and not overly large.
Speaking of ARM, I still can't figure out how ARM was acquired for
$32B.
If even a student can make a synthesizable 32-bit processor in a few
weeks, how much value can there be in a processor? It's almost a
commodity. I know there is a lot of value in prediction pipelines,
cache logic, compilers, etc., but not $32b' worth.
So, maybe the people who SOLD it are laughing their way to the bank.
ARM processor variants have a huge installed base -- I suspect that
went a long way to justifying the $32B. But, if ST started offering
parts with the RISC-V core tomorrow, at a better price, I'd switch.
You would. I probably wouldn't, having a larger team to drag around and
all of the associated infrastructure.
But the cell phone companies, with all that already written codebase and
10s of millions of units sold per year? Not a chance they do. That's
billions of dollars of inertia.
I probably have 20 lines of ARM assembly written, and in retrospect that
could just as well be carefully-crafted C. Assuming that FreeRTOS makes
a port, everything else is C or C++, and could just be compiled for the
new target.
On 5/1/2017 8:42 PM, Tim Wescott wrote:
On Mon, 01 May 2017 17:15:01 -0700, Rob Gaddi wrote:
On 05/01/2017 04:46 PM, Tim Wescott wrote:
On Mon, 01 May 2017 16:07:02 -0700, Kevin Neilson wrote:
I don't know how small the RISC-V can be made. I know there is a
version designed in an ASIC that can compete with the ARM CPUs and
there are more than one version for FPGAs. I would hope they had a
version similar to the ARM CM-1 which is specifically targeted to
programmable logic and not overly large.
Speaking of ARM, I still can't figure out how ARM was acquired for
$32B.
If even a student can make a synthesizable 32-bit processor in a few
weeks, how much value can there be in a processor? It's almost a
commodity. I know there is a lot of value in prediction pipelines,
cache logic, compilers, etc., but not $32b' worth.
So, maybe the people who SOLD it are laughing their way to the bank.
ARM processor variants have a huge installed base -- I suspect that
went a long way to justifying the $32B. But, if ST started offering
parts with the RISC-V core tomorrow, at a better price, I'd switch.
You would. I probably wouldn't, having a larger team to drag around and
all of the associated infrastructure.
But the cell phone companies, with all that already written codebase and
10s of millions of units sold per year? Not a chance they do. That's
billions of dollars of inertia.
I probably have 20 lines of ARM assembly written, and in retrospect that
could just as well be carefully-crafted C. Assuming that FreeRTOS makes
a port, everything else is C or C++, and could just be compiled for the
new target.
Assembly language code is not the only way to be wedded to an
architecture. There are lots of C code written to manage the CPU and
tightly coupled functionality not to mention optimizing code for maximum
performance in an architecture. Then there is the effort required to
optimize the tools. Yes, it is easy to port tools, but to get them
honed for optimal usage requires a lot more effort. I doubt that has
been done for the RISC-V as yet.
I don't know how small the RISC-V can be made. I know there is a
version designed in an ASIC that can compete with the ARM CPUs and there
are more than one version for FPGAs. I would hope they had a version
similar to the ARM CM-1 which is specifically targeted to programmable
logic and not overly large.
Speaking of ARM, I still can't figure out how ARM was acquired for $32B. If even a student can make a synthesizable 32-bit processor in a few weeks, how much value can there be in a processor? It's almost a commodity. I know there is a lot of value in prediction pipelines, cache logic, compilers, etc., but not $32b' worth.
In article <ad71c774-1170-49c3-bd93-efc4a2d63c99@googlegroups.com>,
kevin.neilson@xilinx.com says...
I don't know how small the RISC-V can be made. I know there is a
version designed in an ASIC that can compete with the ARM CPUs and there
are more than one version for FPGAs. I would hope they had a version
similar to the ARM CM-1 which is specifically targeted to programmable
logic and not overly large.
Speaking of ARM, I still can't figure out how ARM was acquired for $32B. If even a student can make a synthesizable 32-bit processor in a few weeks, how much value can there be in a processor? It's almost a commodity. I know there is a lot of value in prediction pipelines, cache logic, compilers, etc., but not $32b' worth.
They didn't buy ARM so much as they bought a concept with a business model
that many companies had foolishly signed up to accept - that's where the
valuation comes from. The actual commodity - like those of pyramid schemes -
(which is what IP is effectively) - is mostly irrelevant.
and yes - a student can design "A processor" - but one that fulfills a market need
that "significantly" (and underlined) moves the market forward adding value
in power, performance, size, manufacturability and so on - is not so easy to do.
(Trust me - I'm working on ideas myself - it's not trivial at all)
A sizeable part of that is hidden in the three key components - the OS
kernel, the basic libraries, and the compiler. The huge majority of the
code on a telephone is cpu agnostic. Most of it got bumped from 32-bit
ARM to 64-bit ARM without much bother, and the 32 to 64 bit jump is
often a bigger port issue than moving between different 32-bit
architectures.
I don't know if the current state of these RISC-V tools are good enough,
however - I believe the Linux port of RISC-V is quite new, and the gcc
port has just been redone. For the big customers, they will want to see
a bit of maturity before considering RISC-V.
For us mere mortals, however, RISC-V is a great idea. If nothing else,
it gives ARM some much-needed competition (which should have come from
MIPS).
On 5/2/2017 3:12 AM, David Brown wrote:
A sizeable part of that is hidden in the three key components - the OS
kernel, the basic libraries, and the compiler. The huge majority of
the code on a telephone is cpu agnostic. Most of it got bumped from
32-bit ARM to 64-bit ARM without much bother, and the 32 to 64 bit jump
is often a bigger port issue than moving between different 32-bit
architectures.
The proportion of the code to be modified is not relevant, only the
amount. It is also not relevant where the code resides. If you want to
port to a new processor you will have to touch every bit of code that is
specific to the processor, period.
On 5/1/2017 11:45 AM, Robert F. Jarnot wrote:
Pretty small (and fast):
https://forums.xilinx.com/t5/Xcell-Daily-Blog/1680-open-source-ISA-RISC-V-processor-cores-run-on-one-Virtex/ba-p/742731
This design has processors plus other interconnecting logic. Hard to
say how much is processor. Taking it all as processor gives around 1.54
kLCs per processor. There are lots of processors that are much smaller
than this.
I don't see *any* info on the speed of these processors, so I don't know
what the "fast" claim is based on.
For those who are confused, RISC-V is not a *processor*, it's an
*architecture*.
Anyone can come up with a microarchitectural implementation of the
architecture - that's the point of an open source ISA. Being open-source
you can also change the architecture - but it's then your problem to
maintain the OS/compiler/etc for your fork of the architecture.
Berkeley happen to have some of their own implementations that they have
also open sourced. These might or might not suit your purposes. Being in
Chisel is one thing that's not everyone's cup of tea.
But the idea is that everyone has an architectural licence, so they are free
to come up with their own implementations, and share them. I suspect that
Microsemi have done their own, rather than importing the Berkeley cores, for
instance.
Theo
Cheerio! Kr. Bonne.
On Tue, 02 May 2017 11:24:10 -0400, rickman wrote:
On 5/2/2017 3:12 AM, David Brown wrote:
A sizeable part of that is hidden in the three key components - the OS
kernel, the basic libraries, and the compiler. The huge majority of
the code on a telephone is cpu agnostic. Most of it got bumped from
32-bit ARM to 64-bit ARM without much bother, and the 32 to 64 bit jump
is often a bigger port issue than moving between different 32-bit
architectures.
The proportion of the code to be modified is not relevant, only the
amount. It is also not relevant where the code resides. If you want to
port to a new processor you will have to touch every bit of code that is
specific to the processor, period.
Yes and no. Everything that David quotes are things that are spread out
over many users and -- with the possible exception of the OS kernel --
are not proprietary. So in commercial terms there's a large customer
base to amortize the cost over -- in open-source terms anyone offering
paid support for the processor would get paid, and the starry-eyed
idealists will do it to help the large number of potential users.
A basic RV32I (the minimal 32 bit user-mode instruction set) is very simple.
Here's one that's about 400 lines of SystemVerilog, that was designed by a
student over a few weeks as a summer project:
https://github.com/ucam-comparch/clarvi
Theo
The code looks pretty clear at first glance. I see a lot of SystemVerilog
constructs that don't look synthesizer-friendly, though.
See http://fpga.org/grvi-phalanx/ Processor clock speed is 300-375 MHz
in a Kintex UltraScale. Placement constraints are required to get this
kind of clock speed, something that Jan Gray is very good at. Follow the
link to the 'Best Short Paper Award' for more details on how the logic
is partitioned between processor and router. For another perspective on
RISC-V see
http://www.adapteva.com/andreas-blog/why-i-will-be-using-the-risc-v-in-my-next-chip/
I had the impression MIPS is still a viable contender in many markets,
but mostly built into ASICs.
I wonder how important the royalties are when designing a CPU into an
SOC. I believe the RISC-V is totally royalty free. But I'm not
familiar with the BSD license, but I think it allows for commercial
versions. So a company may spring up that adds significant value and
charges royalties.