SO we await the first implementation of boh Android on Rv or Windows on Rv. possibly even low level dup of X86 .. not sure where it has advantages besides cost and royalty-free tho. And obscurity.
RISC-V is clean, efficient, robust and extensible. It's open and free (as in freedom) and encourages collaboration. The fact that it's royalty-free is almost irrelevant since most of the expense of a new processor is in the chip design.
The point is that there is a fast growing ecosystem of companies offering various designs and services for RISC-V which makes developing a new chip less risky and less financially onerous.
I work in software and everyone always thinks that any new implementation is 'clean, efficient, robust, and extensible' ... things always look that way until all of the use cases which the old software supported that the new software just ignored or glossed over have to be implemented, after which the new shiny implementation is nearly as bad as the old one was.
The moral of this story is not that rewrites are bad, but the over optimistic belief that the first re-implementation represents how much 'cleaner' the software could have been is usually an illusion. It wil get ugly again fast.
I read the entire RISC-V architecture doc. I am not a hardware engineer so alot of it I could only generalize the meanings and extract some of the details. But some of their choices do seem odd. They are significantly restrictive on how far you can branch in a single instruction. There were other oddities, I don't recall them all.
Some other poster here commented on quite a few good ones in the last RISC-V article. Hopefully he/she can repeat that because I'd like to see those points further discussed.
I imagine some of the attraction is that you aren't paying a license fee, architecture fee, and then per chip royalty with RISC-V compared to ARM. With RISC-V, as I understand it, there is a free version and a licensed version, which means you can play with the SiFive implementation at zero cost and pay for the licensed version if you prefer as well.
I don't know that their decisions wrt branch/jump are a big deal, though it is strange that they limit jumps to unconditional 12 bit offset or conditional 20 bit offset
I agree with everything you said. But I was responding to prisonerX's statement about the design being "clean, efficient, robust, and extensible". From my reading it seems kind of simplistic, which can be confused for 'clean, efficient, and robust'. I am very interested in learning from more those more educated on chip and ISA design whether or not my conclusions are valid.
well... *nix/C have proved over the decades that this can, in fact, be true. whether any given application makes more sense in RISC or CISC is a separate question. compiler writers, from what I've read, hate RISC since implementing a robust C compiler is a pain. there's a reason that COBOL hasn't been fun on RISC. and, of course, it's widely reported that the real hardware in X86 machines is a RISC machine.
Like bji have said, there is nothing "Clean, efficient, Robust and extensible" about RISC-V than say ARMv8. And some CPU veteran might even argue RSIC-V are making some questionable choices in their ISA.
And royalty free is relevant because of its usage for now, and likely foreseeable future are in embedded application.
It will be several more years before RISC-V is able to replace ARM as the main application processor cores in a high end mobile device. The U84 core SiFive announced in October is comparable to the A72 in the Raspberry Pi 4 now, or in high end phones three years ago. RISC-V is catching up, but ARM also continues to move forward. The things Samsung is planning to use RISC-V for at the moment are in peripherals such as the radio baseband or the camera, not the main processor running Android and apps.
I would say they're still behind the ARM Cortex A72/73.
And I doubt they can catch-up with the deployment of the Cortex A77, and possibly a small successor to that in the Cortex A78. Meanwhile, they're actually forgo ARMv8.2 and pushing forward on a "start fresh" with the development of ARMv9 for 2022.
So can RISC-V catch-up by 2022... I doubt it. But I hope they do, in fact, I hope they surpass ARM. I also hope an open-sourced ecosystem emerges to bring a competitive Linux to the mainstream. The current Android-ARM is actually quite proprietary, maybe not as much as Windows-x86 but I digress.
Didn't Softbank buy ARM? They are taking a hit lately by A LOT of different companies. Wework, Wag, whatever else... Now their ARM business is going to face alot of competition in a few years due to their royalties and whatnot...
And Intel and Apple gangbustered their IP sueing leg of the business by taking them to court, possibly cutting off that revenue stream too...
Seems like all tech companies are gunning for them after they destroyed the startup valuations by overbidding massively. Good for them.
Yes Softbank bought ARM. I owned ARM stock at the time, and had to take the payout. I would have rather kept the stock, but that was not an option because it went private.
Let me ask you something if you don't mind. What do you mean by "they destroyed the startup valuations by overbidding"? Are you saying that ARM priced their ISA too high for startups to flourish? or something else. I'm genuinely curious as to what ARM has done in the market to cause the big chip makers to all invest in RISCV.
They created an ~$100bn fund (Vision Fund) to invest in startups and bid prices of various private companies crazy high resulting in massive hype that deflated when they went public (Uber, Lyft) or tried to (weWork).
They're trying to spin up a second equally vast fund as well (Vision Fund 2); but are struggling to find enough both enough investors with billions to blow to fund it and remaining unicorns to blow investors cash on. /worlds smallest violin
Doubtful, they've lost an amazing amount of money on WeWork, that investment alone probably put them negative for years to come. Softbank alone has sunk $10.65Billion into WeWork, they've already written off $4.7Billion and will likely write the rest off at some point in the future.
And the funniest bit is they paid off the wework CEO with $1.7Billion more to walk away. IMO the WeWork investment will never see a profit and I exect they'll write off the whole investment at some point in the future. That entire business isn't worth $500Million let alone the $47Billion that's been invested in it. The only way they could ever recoup that $500Million would be to slash spending and reduce the business to a profitable position but at the rate WeWork is burning cash they are bankrupt in about a year.
"Doubtful, they've lost an amazing amount of money on WeWork, that investment alone probably put them negative for years to come."
true. today. in hindsight. but interest rates, on various fiduciaries, have been sub-2% for ages. so, at those times, the discounted present value, risk adjusted, was way, way more than Treasuries. of course, setting the risk premium requires business smarts, not stat models. SB doesn't always (perhaps, only rarely) do well at that task. separate point from assuming that a big-bucks holder can turn a turd into a Unicorn just by throwing money at it. investing in a better mouse trap, early on, means that you've actually identified a better mouse trap. WeWork, in particular, bought space long and high and sold short and cheap. why anyone with a functioning brain would consider this a Unicorn play just proves that being rich doesn't mean you've been smart. same with Uber/Lyft: a business model which 'disrupts' one of the least lucrative businesses on the face of the planet isn't a Unicorn. well except for what gets stuffed up the butt of an investor.
oh, yeah. The Taxi King in NYC has recently been taken to court for, in essence, blowing up the price of taxi medallions, of which he held many, many. IOW, he created the illusion that taxis were profitable, at least for medallion holders. turns out it was all vapor. could the Uber/Lyft folks be hoodwinked by their own cleverness.
"A Russian immigrant and a cabdriver’s son who got his nickname by building the city’s biggest fleet, Mr. Freidman was a primary architect of some of the tactics used to build the bubble, according to records and interviews." here: https://www.nytimes.com/2019/12/05/nyregion/nyc-ta...
Yet again, naive Americans get taken to the cleaners by Russians. Who knew?
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MASSAMKULABOX - Thursday, December 12, 2019 - link
SO we await the first implementation of boh Android on Rv or Windows on Rv. possibly even low level dup of X86 .. not sure where it has advantages besides cost and royalty-free tho. And obscurity.prisonerX - Thursday, December 12, 2019 - link
RISC-V is clean, efficient, robust and extensible. It's open and free (as in freedom) and encourages collaboration. The fact that it's royalty-free is almost irrelevant since most of the expense of a new processor is in the chip design.The point is that there is a fast growing ecosystem of companies offering various designs and services for RISC-V which makes developing a new chip less risky and less financially onerous.
bji - Thursday, December 12, 2019 - link
I work in software and everyone always thinks that any new implementation is 'clean, efficient, robust, and extensible' ... things always look that way until all of the use cases which the old software supported that the new software just ignored or glossed over have to be implemented, after which the new shiny implementation is nearly as bad as the old one was.The moral of this story is not that rewrites are bad, but the over optimistic belief that the first re-implementation represents how much 'cleaner' the software could have been is usually an illusion. It wil get ugly again fast.
I read the entire RISC-V architecture doc. I am not a hardware engineer so alot of it I could only generalize the meanings and extract some of the details. But some of their choices do seem odd. They are significantly restrictive on how far you can branch in a single instruction. There were other oddities, I don't recall them all.
Some other poster here commented on quite a few good ones in the last RISC-V article. Hopefully he/she can repeat that because I'd like to see those points further discussed.
michael2k - Thursday, December 12, 2019 - link
I imagine some of the attraction is that you aren't paying a license fee, architecture fee, and then per chip royalty with RISC-V compared to ARM. With RISC-V, as I understand it, there is a free version and a licensed version, which means you can play with the SiFive implementation at zero cost and pay for the licensed version if you prefer as well.I don't know that their decisions wrt branch/jump are a big deal, though it is strange that they limit jumps to unconditional 12 bit offset or conditional 20 bit offset
bji - Thursday, December 12, 2019 - link
I agree with everything you said. But I was responding to prisonerX's statement about the design being "clean, efficient, robust, and extensible". From my reading it seems kind of simplistic, which can be confused for 'clean, efficient, and robust'. I am very interested in learning from more those more educated on chip and ISA design whether or not my conclusions are valid.FunBunny2 - Thursday, December 12, 2019 - link
'clean, efficient, robust, and extensible'well... *nix/C have proved over the decades that this can, in fact, be true. whether any given application makes more sense in RISC or CISC is a separate question. compiler writers, from what I've read, hate RISC since implementing a robust C compiler is a pain. there's a reason that COBOL hasn't been fun on RISC. and, of course, it's widely reported that the real hardware in X86 machines is a RISC machine.
ksec - Thursday, December 12, 2019 - link
Like bji have said, there is nothing "Clean, efficient, Robust and extensible" about RISC-V than say ARMv8. And some CPU veteran might even argue RSIC-V are making some questionable choices in their ISA.And royalty free is relevant because of its usage for now, and likely foreseeable future are in embedded application.
WPX00 - Saturday, December 14, 2019 - link
also risc-v was developed here in berkeley... and as a berkeley alum it'd be awesome to see it take off. selfish i know.brucehoult - Thursday, December 12, 2019 - link
It will be several more years before RISC-V is able to replace ARM as the main application processor cores in a high end mobile device. The U84 core SiFive announced in October is comparable to the A72 in the Raspberry Pi 4 now, or in high end phones three years ago. RISC-V is catching up, but ARM also continues to move forward. The things Samsung is planning to use RISC-V for at the moment are in peripherals such as the radio baseband or the camera, not the main processor running Android and apps.Kangal - Friday, December 13, 2019 - link
I would say they're still behind the ARM Cortex A72/73.And I doubt they can catch-up with the deployment of the Cortex A77, and possibly a small successor to that in the Cortex A78. Meanwhile, they're actually forgo ARMv8.2 and pushing forward on a "start fresh" with the development of ARMv9 for 2022.
So can RISC-V catch-up by 2022... I doubt it.
But I hope they do, in fact, I hope they surpass ARM. I also hope an open-sourced ecosystem emerges to bring a competitive Linux to the mainstream. The current Android-ARM is actually quite proprietary, maybe not as much as Windows-x86 but I digress.
Fataliity - Thursday, December 12, 2019 - link
Didn't Softbank buy ARM? They are taking a hit lately by A LOT of different companies. Wework, Wag, whatever else... Now their ARM business is going to face alot of competition in a few years due to their royalties and whatnot...And Intel and Apple gangbustered their IP sueing leg of the business by taking them to court, possibly cutting off that revenue stream too...
Seems like all tech companies are gunning for them after they destroyed the startup valuations by overbidding massively. Good for them.
bji - Thursday, December 12, 2019 - link
Yes Softbank bought ARM. I owned ARM stock at the time, and had to take the payout. I would have rather kept the stock, but that was not an option because it went private.Morawka - Thursday, December 12, 2019 - link
Let me ask you something if you don't mind. What do you mean by "they destroyed the startup valuations by overbidding"? Are you saying that ARM priced their ISA too high for startups to flourish? or something else. I'm genuinely curious as to what ARM has done in the market to cause the big chip makers to all invest in RISCV.DanNeely - Thursday, December 12, 2019 - link
They is Softbank not Arm.They created an ~$100bn fund (Vision Fund) to invest in startups and bid prices of various private companies crazy high resulting in massive hype that deflated when they went public (Uber, Lyft) or tried to (weWork).
They're trying to spin up a second equally vast fund as well (Vision Fund 2); but are struggling to find enough both enough investors with billions to blow to fund it and remaining unicorns to blow investors cash on. /worlds smallest violin
FunBunny2 - Thursday, December 12, 2019 - link
"/worlds smallest violin"yeah, but it beats, in an expected present value sense, buying Treasuries!!
rahvin - Friday, December 13, 2019 - link
Doubtful, they've lost an amazing amount of money on WeWork, that investment alone probably put them negative for years to come. Softbank alone has sunk $10.65Billion into WeWork, they've already written off $4.7Billion and will likely write the rest off at some point in the future.And the funniest bit is they paid off the wework CEO with $1.7Billion more to walk away. IMO the WeWork investment will never see a profit and I exect they'll write off the whole investment at some point in the future. That entire business isn't worth $500Million let alone the $47Billion that's been invested in it. The only way they could ever recoup that $500Million would be to slash spending and reduce the business to a profitable position but at the rate WeWork is burning cash they are bankrupt in about a year.
FunBunny2 - Friday, December 13, 2019 - link
"Doubtful, they've lost an amazing amount of money on WeWork, that investment alone probably put them negative for years to come."true. today. in hindsight. but interest rates, on various fiduciaries, have been sub-2% for ages. so, at those times, the discounted present value, risk adjusted, was way, way more than Treasuries. of course, setting the risk premium requires business smarts, not stat models. SB doesn't always (perhaps, only rarely) do well at that task. separate point from assuming that a big-bucks holder can turn a turd into a Unicorn just by throwing money at it. investing in a better mouse trap, early on, means that you've actually identified a better mouse trap. WeWork, in particular, bought space long and high and sold short and cheap. why anyone with a functioning brain would consider this a Unicorn play just proves that being rich doesn't mean you've been smart. same with Uber/Lyft: a business model which 'disrupts' one of the least lucrative businesses on the face of the planet isn't a Unicorn. well except for what gets stuffed up the butt of an investor.
FunBunny2 - Friday, December 13, 2019 - link
oh, yeah. The Taxi King in NYC has recently been taken to court for, in essence, blowing up the price of taxi medallions, of which he held many, many. IOW, he created the illusion that taxis were profitable, at least for medallion holders. turns out it was all vapor. could the Uber/Lyft folks be hoodwinked by their own cleverness."A Russian immigrant and a cabdriver’s son who got his nickname by building the city’s biggest fleet, Mr. Freidman was a primary architect of some of the tactics used to build the bubble, according to records and interviews."
here: https://www.nytimes.com/2019/12/05/nyregion/nyc-ta...
Yet again, naive Americans get taken to the cleaners by Russians. Who knew?