5 ms·

>teaching MIPS as the most elegant example of a RISC processor elegant as in simplified to the bone, but also a market failure compared to not so reduced ARM

by rasz_pl 12y ago

>teaching MIPS as the most elegant example of a RISC processor elegant as in simplified to the bone, but also a market failure compared to not so reduced ARM >You’ve been here for two months, and now you want to give our IP away! haha, nice try Imagination Technologies, you arent giving anything for free. Later on in the blog post is a mere mention of all the proprietary IP, patents and licenses they are NOT granting/licensing. This is a huge win for Imagination, somehow they managed to convince a ton of universities to base their curriculum on Img proprietary design, this is as big as Nvidia "helping out" with heterogenous computing courses resulting in universities universally (hah) ignoring OpenCL, and exclusively teaching proprietary CUDA.

alexvoica 12y ago
This is not simplified, we include the full RTL and all the building blocks required to run Linux (cache controllers, MMU, debug interface, load/store unit etc.). We are granting an open license, which means you can see the code. CPU IP usually includes many options (i.e. parameters) that need to be set by design teams before doing any FPGA integration work (synthesis, functional simulation and verification, place and route, etc.). Setting those parameters up requires a lot of expertise which is usually accumulated over years of work in SoC design. The blog article mentions a case where a university struggled to configure the MIPSfpga CPU because (naturally) IP can be quite complex, especially if you haven’t used it before. So we’ve actually done a lot of work to create a pre-configured, pre-validated version that is easy to use by academics (lecturers, students, etc.) for FPGAs. Of course, we also state in the press release that users can change it but they need to talk to us first to ensure that the changes they make are valid and sensible. The last thing you want is to break a CPU architecture; this will affect not just the behavior of the hardware, but also the toolchain.
- ris 12y ago
  "We are granting an open license" I know it's become a bit of a tradition to abuse the word "open" in technology circles, but this is really pushing it a bit far. Even Microsoft didn't have the gall to call its "shared source" initiative "open".
userbinator 12y ago
but also a market failure compared to not so reduced ARM There are tons of MIPS SoCs out there, mostly in various Chinese devices (the ones which are too cheap for ARM?) so I wouldn't say they failed completely, but in terms of performance or power efficiency MIPS is definitely behind compared to ARM or x86: http://www.extremetech.com/extreme/188396-the-final-isa-showdown-is-arm-x86-or-mips-intrinsically-more-power-efficient http://www.extremetech.com/extreme/188396-the-final-isa-show... AFAIK all the patents on early x86 have expired, and IMHO that's a far more interesting architecture to study... http://zet.aluzina.org/index.php/Zet_processor http://zet.aluzina.org/index.php/Zet_processor
- solarexplorer 12y ago
  I disagree. This comparison is extremely unfair because they used a chineese clone instead of the real CPU/compiler from MIPS...
  - userbinator 12y ago
    What would the "real CPU from MIPS" be, and how much difference would that make...? Loongson is a licensed design. As for compilers, neither ARM's nor Intel's compiler were used for the other CPUs, so I think that's a fair comparison. ...and I thought one of the reasons to choose a very simple RISC like MIPS was that its simplicity made compiler optimisations easier?
    - solarexplorer 12y ago
      AFAIK Loongson just licensed the patent necessary to implement the MIPS ISA but the implementation was done by chineese academia without any intervention from MIPS. You cannont judge the quality of MIPS processors in general by looking only at one chineese clone...
- ris 12y ago
  "IMHO that's a far more interesting architecture to study" By interesting do you mean awful? The only reason for clinging on to x86 is maintaining compatibility with old proprietary (almost entirely windows) software.
jeffbush 12y ago
Many set top boxes and TVs use MIPS. I don't think it's accurate to call it a failure, although ARM certainly has more volume.
- abrowne 12y ago
  My internet radio, too.
protomyth 12y ago
> elegant as in simplified to the bone, but also a market failure compared to not so reduced ARM ah, to have such a failure that gets my chip in embedded use for decades including some game machines and some not too shabby workstations
glabifrons 12y ago
In addition to all of the other examples given, countless SoHo routers (just about everything from the old WRT54G workhorse on up) run MIPS processors. Edit: Fixed typo.

by rasz_pl 12y ago

alexvoica 12y ago

This is not simplified, we include the full RTL and all the building blocks required to run Linux (cache controllers, MMU, debug interface, load/store unit etc.). We are granting an open license, which means you can see the code. CPU IP usually includes many options (i.e. parameters) that need to be set by design teams before doing any FPGA integration work (synthesis, functional simulation and verification, place and route, etc.). Setting those parameters up requires a lot of expertise which is usually accumulated over years of work in SoC design. The blog article mentions a case where a university struggled to configure the MIPSfpga CPU because (naturally) IP can be quite complex, especially if you haven’t used it before. So we’ve actually done a lot of work to create a pre-configured, pre-validated version that is easy to use by academics (lecturers, students, etc.) for FPGAs. Of course, we also state in the press release that users can change it but they need to talk to us first to ensure that the changes they make are valid and sensible. The last thing you want is to break a CPU architecture; this will affect not just the behavior of the hardware, but also the toolchain.

ris 12y ago
"We are granting an open license" I know it's become a bit of a tradition to abuse the word "open" in technology circles, but this is really pushing it a bit far. Even Microsoft didn't have the gall to call its "shared source" initiative "open".

userbinator 12y ago

but also a market failure compared to not so reduced ARM There are tons of MIPS SoCs out there, mostly in various Chinese devices (the ones which are too cheap for ARM?) so I wouldn't say they failed completely, but in terms of performance or power efficiency MIPS is definitely behind compared to ARM or x86: http://www.extremetech.com/extreme/188396-the-final-isa-showdown-is-arm-x86-or-mips-intrinsically-more-power-efficient http://www.extremetech.com/extreme/188396-the-final-isa-show... AFAIK all the patents on early x86 have expired, and IMHO that's a far more interesting architecture to study... http://zet.aluzina.org/index.php/Zet_processor http://zet.aluzina.org/index.php/Zet_processor

solarexplorer 12y ago
I disagree. This comparison is extremely unfair because they used a chineese clone instead of the real CPU/compiler from MIPS...
- userbinator 12y ago
  What would the "real CPU from MIPS" be, and how much difference would that make...? Loongson is a licensed design. As for compilers, neither ARM's nor Intel's compiler were used for the other CPUs, so I think that's a fair comparison. ...and I thought one of the reasons to choose a very simple RISC like MIPS was that its simplicity made compiler optimisations easier?
  - solarexplorer 12y ago
    AFAIK Loongson just licensed the patent necessary to implement the MIPS ISA but the implementation was done by chineese academia without any intervention from MIPS. You cannont judge the quality of MIPS processors in general by looking only at one chineese clone...
ris 12y ago
"IMHO that's a far more interesting architecture to study" By interesting do you mean awful? The only reason for clinging on to x86 is maintaining compatibility with old proprietary (almost entirely windows) software.

jeffbush 12y ago

Many set top boxes and TVs use MIPS. I don't think it's accurate to call it a failure, although ARM certainly has more volume.

abrowne 12y ago
My internet radio, too.

protomyth 12y ago

> elegant as in simplified to the bone, but also a market failure compared to not so reduced ARM ah, to have such a failure that gets my chip in embedded use for decades including some game machines and some not too shabby workstations

glabifrons 12y ago

In addition to all of the other examples given, countless SoHo routers (just about everything from the old WRT54G workhorse on up) run MIPS processors. Edit: Fixed typo.