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| From | David Brown <david.brown@hesbynett.no> |
|---|---|
| Newsgroups | comp.lang.c |
| Subject | Re: Does each core of 8-core Intel processor has an independent floating X87 unit? |
| Date | 2015-04-07 23:40 +0200 |
| Organization | A noiseless patient Spider |
| Message-ID | <mg1iri$588$1@dont-email.me> (permalink) |
| References | (5 earlier) <mfrpm1$oui$1@news.albasani.net> <bcef1fdb-0b53-4073-a533-acf051d11ab4@googlegroups.com> <mfruf3$1ri$1@news.albasani.net> <mg03c4$lq$1@dont-email.me> <mg0t54$gtt$1@news.albasani.net> |
On 07/04/15 17:26, BGB wrote: > On 4/7/2015 3:10 AM, David Brown wrote: >> On 05/04/15 20:17, BGB wrote: >>> On 4/5/2015 12:08 PM, fir wrote: >>>> W dniu niedziela, 5 kwietnia 2015 18:59:54 UTC+2 użytkownik BGB >>>> napisał: >>>>> On 4/5/2015 11:40 AM, Melzzzzz wrote: >>>>>> On Sun, 05 Apr 2015 11:21:52 -0500 >>>>>> BGB <cr88192@hotmail.com> wrote: >>>>>> >>>>>>> On 4/5/2015 10:35 AM, Melzzzzz wrote: >>>>>>>> On Sun, 05 Apr 2015 17:17:42 +0200 >>>>>>>> Noob <root@127.0.0.1> wrote: >>>>>>>> >>>>>>>>> >>>>>>>>> And x87 is obsolete. >>>>>>>>> >>>>>>>> >>>>>>>> Who said that? >>>>>>>> >>>>>>> >>>>>>> AMD mostly. >>>>>>> >>>>>>> >>>>>>> when they created the x86-64 / AMD64 ISA, IIRC they also classified >>>>>>> x87 (among other things) as a deprecated feature. the main existing >>>>>>> 64-bit ABIs (SysV/AMD64 and Win64) also regard x87 as deprecated >>>>>>> AFAIK. >>>>>>> >>>>>>> I don't know if Intel has said anything on the matter, but either >>>>>>> way, x87 hasn't really been a big thing in quite a while now. >>>>>>> >>>>>>> however, both x87 and most of the deprecated instructions have been >>>>>>> kept around, kind of still needed if you want the processors to >>>>>>> still >>>>>>> be able to run 16-bit or 32-bit software (or the possibility of >>>>>>> pesky >>>>>>> runtime library implementers using x87 for sin/cos/tan/... rather >>>>>>> than calculating them via the Taylor Series or similar). >>>>>>> >>>>>> >>>>>> What about extended precision float? Compilers still generate >>>>>> x87 instructions and take adequate parameters for that number? >>>>>> >>>>> >>>>> depends on compiler and OS. >>>>> >>>>> GCC and Linux, yes. >>>>> >>>>> had partly overlooked these. >>>>> >>>>> but, yes, it seems SysV/AMD64 still allows x87. >>>>> >>>>> >>>>> not sure what GCC does on Win64, but if they are using 80-bit >>>>> floats via >>>>> x87 on Win64, this is basically a "thin ice" scenario AFAIK, and may >>>>> break hard in Ring-0 / WDM code or similar. >>>>> >>>>> >>>>> Microsoft's compiler treats "long double" as equivalent to >>>>> "double", so >>>>> 80-bit floats don't really exist on Win64 to begin with, so no issue >>>>> here. >>>> >>>> not sure if this is microsoft who decides here or intel or who.. >>>> not sure also if they should deprecate or drop x87 of no, maybe they >>>> should.. bit hard to say >>>> (some could say they could drop x64 at all and build something nicer) >>>> >>> >>> each party says something slightly different. >>> >>> >>> thought was, eventually it may go away. >>> >>> but, this is unlikely in mainstream processors anytime soon, and would >>> most likely happen first with embedded processors (more likely in a >>> scenario where x86-64 and AArch64 are start trying to compete on price >>> point to displace 32-bit ARM in lower-end phones and in >>> consumer-electronics, vs at present competing more over high-end >>> smartphones and netbooks and tablets). >>> >>> >>> this will probably be also about the time when you can get a reasonably >>> cheap board with a 64-bit SoC on it for sticking in electronics >>> projects, whereas ATM $15 or $20 can get you a board with a 32-bit >>> processor (8/16 bit MCUs are cheaper, and are easier to get in >>> self-contained DIP modules, but typically suffer from a severe lack of >>> RAM, but some options come as small PCB's which can still be stuck into >>> DIP sockets via pin-headers, and maybe secured with hot-glue). >>> >> >> There are still a few hobby developers who see DIP as an advantage, but >> as a proportion of devices, DIP chips or modules are negligible. Small >> developers often prefer wider pin spacing packages over the densest >> devices, and they certainly prefer small pin counts, but few people >> seriously use DIP any more. >> > > for a hobbyist though, DIP is very useful when building custom (mostly > one-off) boards by hand (using a lot of wire-wrap and soldering). > > and DIP sockets are pretty useful when you want parts to be removable. That's the theory, and it is wildly over-estimated in importance. Parts are seldom removed - certainly not the microcontroller. It's true that some people insist on making life harder for themselves by trying to use DIP packages - resulting in bigger, slower, more expensive and more limited microcontrollers when they could have easily used something much better on a ready-made microcontroller board. There are people who would rather spend days extra on an inferior system rather than spend a few extra pennies. But as I said, such uses are extremely minor in the overall picture. > > > luckily, my projects tend to be big enough that I can have multiple boards. > > for example, a small robot project of mine currently has 3 boards: > a Raspberry Pi; > a motor-interface board (has a few transistor H-bridges and similar on it); > a power-regulator board, which mostly has voltage-regulators, some > diodes and capacitors, ... (its main thing is to supply 5v power for the > RPi and the cameras and a few other things). > > there is also some mostly glue-stuff done on a breadboard. > > > for another project, I may use a Raspberry Pi 2 (mostly for sake of it > having a multi-core processor, so RT and non-RT stuff can coexist more > peacefully). > > > but, the thought would be it would be nice if something along similar > lines (capability wise) to a Raspberry Pi 2 could be crammed into a more > compact package (though there is a RPi variant which fits into > re-purposed SO-DIMM slots). > > > >> And while 64-bit ARM may gradually replace 32-bit ARM in phones, >> tablets, etc., it will not do so for small embedded devices where 32-bit >> ARM Cortex-M is becoming dominant (and often significantly cheaper than >> 8/16-bit micros - you can get a 32-bit ARM device for under $0.50). >> > > yeah. > > an ARM Cortex-M is at this point a bit cheaper than, say, a PIC32 > device. though in quick searches, I had seen PIC32 devices with a wider > temperature range than I have seen Cortex-M devices available for. It's a pity Microchip have made such a pig's breakfast with the PIC32 - it really spoiled the reputation of MIPS in the small microcontroller market. It is a pointless device. (But details here would be even more seriously off-topic in c.l.c.). > > I suspect 64-bit could happen in micros, though probably a bit further > in the future (currently nowhere near enough RAM in most of them to make > this worthwhile). 64-bit microcontrollers have been mainstream in particular parts of the embedded market for longer than they have been common on desktops. But they are only used where they are /useful/ (typically high-end networking equipment and other communication devices, as well as audio/video processing). And that is how it will continue to be - they will only become common in systems where it is useful to have more than 4 GB address space, or more serious processing power. > > >> But for that sort of system, floating point precision or tight IEEE >> compliance is usually irrelevant. Single-precision 32-bit floats are >> normally enough on the small proportion of systems that need floating >> point at all. >> > > yeah. > > most stuff can be done either with integer or fixed-point. >
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Does each core of 8-core Intel processor has an independent floating X87 unit? Weng Tianxiang <wtxwtx@gmail.com> - 2015-04-05 06:50 -0700
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Noob <root@127.0.0.1> - 2015-04-05 17:17 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Melzzzzz <mel@zzzzz.com> - 2015-04-05 17:35 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 11:21 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Melzzzzz <mel@zzzzz.com> - 2015-04-05 18:40 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 11:56 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? fir <profesor.fir@gmail.com> - 2015-04-05 10:08 -0700
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 13:17 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-07 10:10 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-07 10:26 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-07 23:40 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Bartc <bc@freeuk.com> - 2015-04-07 23:06 +0100
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-08 01:23 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-07 23:15 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-07 20:16 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-08 09:27 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-08 09:44 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Melzzzzz <mel@zzzzz.com> - 2015-04-05 19:37 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 18:50 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-05 22:29 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 23:09 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-06 01:54 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-06 07:44 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-07 10:16 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-07 03:32 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-07 12:48 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Richard Heathfield <rjh@cpax.org.uk> - 2015-04-07 11:57 +0100
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-07 13:33 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-07 15:21 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-04-07 17:15 +0000
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Tim Prince <tprince@computer.org> - 2015-04-07 14:21 -0400
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Keith Thompson <kst-u@mib.org> - 2015-04-05 13:08 -0700
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 15:27 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Noob <root@127.0.0.1> - 2015-04-05 19:04 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Melzzzzz <mel@zzzzz.com> - 2015-04-05 19:38 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? fir <profesor.fir@gmail.com> - 2015-04-05 10:46 -0700
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Keith Thompson <kst-u@mib.org> - 2015-04-05 13:12 -0700
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? fir <profesor.fir@gmail.com> - 2015-04-05 09:51 -0700
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 12:18 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? jacobnavia <jacob@jacob.remcomp.fr> - 2015-04-06 01:30 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 19:27 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? christian.bau@cbau.wanadoo.co.uk - 2015-04-07 23:58 -0700
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-08 08:08 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Melzzzzz <mel@zzzzz.com> - 2015-04-06 03:36 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-07 10:27 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-07 10:39 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? christian.bau@cbau.wanadoo.co.uk - 2015-04-07 23:47 -0700
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 11:04 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Melzzzzz <mel@zzzzz.com> - 2015-04-05 18:20 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-05 11:43 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? glen herrmannsfeldt <gah@ugcs.caltech.edu> - 2015-04-05 20:28 +0000
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Malcolm McLean <malcolm.mclean5@btinternet.com> - 2015-04-05 14:46 -0700
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? fir <profesor.fir@gmail.com> - 2015-04-05 15:01 -0700
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Keith Thompson <kst-u@mib.org> - 2015-04-05 13:17 -0700
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Paul <nospam@needed.com> - 2015-04-05 14:31 -0400
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-07 11:01 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-05 22:34 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Weng Tianxiang <wtxwtx@gmail.com> - 2015-04-05 23:39 -0700
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-06 02:06 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-06 08:57 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-06 12:38 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-06 16:30 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Stephen Sprunk <stephen@sprunk.org> - 2015-04-06 17:10 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Ian Collins <ian-news@hotmail.com> - 2015-04-07 10:16 +1200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Melzzzzz <mel@zzzzz.com> - 2015-04-07 02:23 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-06 17:36 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-06 17:41 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-06 20:09 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Richard Damon <Richard@Damon-Family.org> - 2015-04-06 22:44 -0400
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? David Brown <david.brown@hesbynett.no> - 2015-04-07 11:11 +0200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Weng Tianxiang <wtxwtx@gmail.com> - 2015-04-06 08:04 -0700
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-06 12:43 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Paul <nospam@needed.com> - 2015-04-06 14:52 -0400
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? BGB <cr88192@hotmail.com> - 2015-04-06 17:09 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Paul <nospam@needed.com> - 2015-04-06 11:11 -0400
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-06 12:47 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Stephen Sprunk <stephen@sprunk.org> - 2015-04-06 17:15 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Robert Wessel <robertwessel2@yahoo.com> - 2015-04-07 03:41 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Ian Collins <ian-news@hotmail.com> - 2015-04-07 21:19 +1200
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Stephen Sprunk <stephen@sprunk.org> - 2015-04-07 10:37 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Tim Prince <tprince@computer.org> - 2015-04-07 12:13 -0400
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Stephen Sprunk <stephen@sprunk.org> - 2015-04-09 12:34 -0500
Re: Does each core of 8-core Intel processor has an independent floating X87 unit? Stephen Sprunk <stephen@sprunk.org> - 2015-04-07 10:48 -0500
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