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Re: ARM Cortex Mx vs the rest of the gang

From Dimiter_Popoff <dp@tgi-sci.com>
Newsgroups comp.arch.embedded
Subject Re: ARM Cortex Mx vs the rest of the gang
Date 2017-07-15 04:04 +0300
Organization TGI
Message-ID <okbpg3$cad$1@dont-email.me> (permalink)
References (7 earlier) <ok2u4n$1dfc$1@gioia.aioe.org> <ok37se$9qg$1@dont-email.me> <ok3m7t$fbg$1@gioia.aioe.org> <okbdr1$b3d$1@dont-email.me> <okbidq$19rl$1@gioia.aioe.org>

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On 15.7.2017 г. 02:00, Chris wrote:
> On 07/14/17 21:45, Dimiter_Popoff wrote:
>
>>
>> I can't think of a single non-68k/coldfire processor which has the
>> multiple priority interrupt levels (but I don't know ARM) or an
>> equivalent. Did ARM come that much of age? I'd be surprised.
>
> Neither do I. At the time, we avidly followed developments in Byte
> magazine and remember being so impressed by the 68K architecture,
> went out and spent a fortune on the 68KECB, just to learn about it.
> It's the architecture that all others since have been compared
> against, often unfavorably, but Motorola were influenced by
> older mini architectures such as pdp11, or even Vax. "Get as much
> mini arch into a micro as possible", I think was the reasoning. I
> bet it would still be competitive even now with modern process
> technology, but of course, CISC is out of fashion these days.

Well the prioritized scheme needs not be on CISC, e.g. on power a
pair of registers to save the PC and the MSR per priority level
would suffice (this is how they did the FIRQ). Of course and a
RTI (rfi on power) opcode, different per level - and working :-).

>
>>
>> Even power do not have it, some cores do have a FIRQ which has
>> priority over IRQ (i.e. will interrupt an IRQ handler). On the core
>> I use (and did not use the FIRQ) there is a hardware mess with the
>> return from FIRQ opcodes - and IIRC the suggested workaround would
>> kill the "FIRQ interrupt IRQ" capability, LOL. (I think it was
>> to copy the FIRQ return registers to those for IRQ and exectute
>> a return from IRQ.... too bad if you had just interrupted an IRQ
>> handler).
>>
>
> Older arm arch was a mess, imho, looking like bits had been glued
> on all over the place. The idea of IRQ and FIRQ harks back to 6800
> and 6502's IRQ and NMI, which served similar functions.

NMI was too cruel, I used it for step by step tracing only. They
introduced the FIRQ on the 6809 (they being Motorola, obviously);
perhaps were forced to as IRQ pushed all the registers and the 09 had
a lot more than the 6800 (which pushed all IIRC in about 20uS @1 MHz...)
The FIRQ on the 09 pushed just the CCR and the PC, 3 bytes.

> If they could
> build compiler friendly orthoganal architecture micros 30 years ago,
> there's no excuse not to do it now...

The guy who made power must have been really good, apart from the
missing interrupt levels I can't say I have many wishes. In fact I
live fine as it is, I just think of the moment I might need them :D.
This has been some 30 years ago... still the architecture the rest want
to catch up with.

Then on the mpc5200B (the one in heaviest use here) there is an
interrupt peripheral, which prioritizes the interrupts 68k style
and feeds them via the single IRQ line to the core. I have not
needed to do it but with a few reads and writes at the beginning of
the IRQ handler and perhaps at its end one could emulate the complete
68k thing I believe (never seriously looked into it though, would
take unmasking the irq in the core after stacking some stuff and
making the intrerrupt controller shut up for the current and lower
priorities).

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

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Thread

ARM Cortex Mx vs the rest of the gang Klaus Kragelund <klauskvik@hotmail.com> - 2017-05-30 05:11 -0700
  ARM Cortex Mx vs the rest of the gang klaus.kragelund@gmail.com - 2017-05-30 05:48 -0700
    Re: ARM Cortex Mx vs the rest of the gang Uwe Bonnes <bon@hertz.tu-darmstadt.de> - 2017-05-30 14:32 +0000
      Re: ARM Cortex Mx vs the rest of the gang Tim Wescott <seemywebsite@myfooter.really> - 2017-05-30 22:07 -0500
        Re: ARM Cortex Mx vs the rest of the gang rickman <gnuarm@gmail.com> - 2017-05-30 23:57 -0400
          Re: ARM Cortex Mx vs the rest of the gang David Brown <david.brown@hesbynett.no> - 2017-05-31 12:08 +0200
            Re: ARM Cortex Mx vs the rest of the gang rickman <gnuarm@gmail.com> - 2017-05-31 09:11 -0400
              Re: ARM Cortex Mx vs the rest of the gang Tim Wescott <seemywebsite@myfooter.really> - 2017-06-01 15:17 -0500
                Re: ARM Cortex Mx vs the rest of the gang rickman <gnuarm@gmail.com> - 2017-06-01 16:27 -0400
                Re: ARM Cortex Mx vs the rest of the gang rickman <gnuarm@gmail.com> - 2017-06-01 16:30 -0400
            Re: ARM Cortex Mx vs the rest of the gang Tim Wescott <seemywebsite@myfooter.really> - 2017-06-01 15:17 -0500
  Re: ARM Cortex Mx vs the rest of the gang Don Y <blockedofcourse@foo.invalid> - 2017-05-30 07:31 -0700
    Re: ARM Cortex Mx vs the rest of the gang Klaus Kragelund <klauskvik@hotmail.com> - 2017-05-30 08:07 -0700
      Re: ARM Cortex Mx vs the rest of the gang George Neuner <gneuner2@comcast.net> - 2017-05-31 00:38 -0400
      Re: ARM Cortex Mx vs the rest of the gang Don Y <blockedofcourse@foo.invalid> - 2017-05-30 22:14 -0700
  Re: ARM Cortex Mx vs the rest of the gang rickman <gnuarm@gmail.com> - 2017-05-30 10:53 -0400
  Re: ARM Cortex Mx vs the rest of the gang StateMachineCOM <statemachineguru@gmail.com> - 2017-06-07 12:58 -0700
    Re: ARM Cortex Mx vs the rest of the gang Klaus Kragelund <klauskvik@hotmail.com> - 2017-06-07 13:27 -0700
    Re: ARM Cortex Mx vs the rest of the gang Jack <jack4747@gmail.com> - 2017-06-07 23:24 -0700
      Re: ARM Cortex Mx vs the rest of the gang StateMachineCOM <statemachineguru@gmail.com> - 2017-06-12 07:21 -0700
        Re: ARM Cortex Mx vs the rest of the gang Dimiter_Popoff <dp@tgi-sci.com> - 2017-06-12 17:57 +0300
          Re: ARM Cortex Mx vs the rest of the gang Don Y <blockedofcourse@foo.invalid> - 2017-06-12 10:10 -0700
            Re: ARM Cortex Mx vs the rest of the gang Dimiter_Popoff <dp@tgi-sci.com> - 2017-06-12 22:06 +0300
              Re: ARM Cortex Mx vs the rest of the gang Don Y <blockedofcourse@foo.invalid> - 2017-06-12 12:19 -0700
                Re: ARM Cortex Mx vs the rest of the gang Dimiter_Popoff <dp@tgi-sci.com> - 2017-06-12 23:04 +0300
                Re: ARM Cortex Mx vs the rest of the gang Don Y <blockedofcourse@foo.invalid> - 2017-06-12 14:34 -0700
                Re: ARM Cortex Mx vs the rest of the gang Dimiter_Popoff <dp@tgi-sci.com> - 2017-06-13 02:44 +0300
                Re: ARM Cortex Mx vs the rest of the gang Don Y <blockedofcourse@foo.invalid> - 2017-06-12 17:31 -0700
        Re: ARM Cortex Mx vs the rest of the gang Jack <jack4747@gmail.com> - 2017-06-12 08:04 -0700
        Re: ARM Cortex Mx vs the rest of the gang Don Y <blockedofcourse@foo.invalid> - 2017-06-12 09:54 -0700
          Re: ARM Cortex Mx vs the rest of the gang Chris <xxx.syseng.yyy@gfsys.co.uk> - 2017-07-10 13:30 +0000
            Re: ARM Cortex Mx vs the rest of the gang Don Y <blockedofcourse@foo.invalid> - 2017-07-10 16:03 -0700
              Re: ARM Cortex Mx vs the rest of the gang Chris <xxx.syseng.yyy@gfsys.co.uk> - 2017-07-11 16:24 +0000
                Re: ARM Cortex Mx vs the rest of the gang Don Y <blockedofcourse@foo.invalid> - 2017-07-11 12:15 -0700
                Re: ARM Cortex Mx vs the rest of the gang Chris <xxx.syseng.yyy@gfsys.co.uk> - 2017-07-11 23:16 +0000
                Re: ARM Cortex Mx vs the rest of the gang Don Y <blockedofcourse@foo.invalid> - 2017-07-12 11:44 -0700
                Re: ARM Cortex Mx vs the rest of the gang George Neuner <gneuner2@comcast.net> - 2017-07-12 17:46 -0400
                Re: ARM Cortex Mx vs the rest of the gang Don Y <blockedofcourse@foo.invalid> - 2017-07-12 18:12 -0700
                Re: ARM Cortex Mx vs the rest of the gang Anders.Montonen@kapsi.spam.stop.fi.invalid - 2017-07-13 11:42 +0000
                Re: ARM Cortex Mx vs the rest of the gang Don Y <blockedofcourse@foo.invalid> - 2017-07-13 21:38 -0700
                Re: ARM Cortex Mx vs the rest of the gang David Brown <david.brown@hesbynett.no> - 2017-07-13 23:31 +0200
                Re: ARM Cortex Mx vs the rest of the gang Chris <xxx.syseng.yyy@gfsys.co.uk> - 2017-07-14 15:27 +0000
                Re: ARM Cortex Mx vs the rest of the gang David Brown <david.brown@hesbynett.no> - 2017-07-14 17:38 +0200
                Re: ARM Cortex Mx vs the rest of the gang Chris <xxx.syseng.yyy@gfsys.co.uk> - 2017-07-14 16:03 +0000
                Re: ARM Cortex Mx vs the rest of the gang David Brown <david.brown@hesbynett.no> - 2017-07-14 20:20 +0200
                Re: ARM Cortex Mx vs the rest of the gang Chris <xxx.syseng.yyy@gfsys.co.uk> - 2017-07-14 18:59 +0000
                Re: ARM Cortex Mx vs the rest of the gang Chris <xxx.syseng.yyy@gfsys.co.uk> - 2017-07-14 17:17 +0000
                Re: ARM Cortex Mx vs the rest of the gang Dimiter_Popoff <dp@tgi-sci.com> - 2017-07-15 00:45 +0300
                Re: ARM Cortex Mx vs the rest of the gang Chris <xxx.syseng.yyy@gfsys.co.uk> - 2017-07-14 23:00 +0000
                Re: ARM Cortex Mx vs the rest of the gang Dimiter_Popoff <dp@tgi-sci.com> - 2017-07-15 04:04 +0300
                Re: ARM Cortex Mx vs the rest of the gang Chris <xxx.syseng.yyy@gfsys.co.uk> - 2017-07-16 16:58 +0000
                Re: ARM Cortex Mx vs the rest of the gang Richard Damon <Richard@Damon-Family.org> - 2017-07-14 20:05 -0400
                Re: ARM Cortex Mx vs the rest of the gang Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2017-07-15 11:53 +0300
                Re: ARM Cortex Mx vs the rest of the gang David Brown <david.brown@hesbynett.no> - 2017-07-15 12:05 +0200
                Re: ARM Cortex Mx vs the rest of the gang Anders.Montonen@kapsi.spam.stop.fi.invalid - 2017-07-20 11:11 +0000
                Re: ARM Cortex Mx vs the rest of the gang Anders.Montonen@kapsi.spam.stop.fi.invalid - 2017-07-20 10:29 +0000
        Re: ARM Cortex Mx vs the rest of the gang "Boudewijn Dijkstra" <sp4mtr4p.boudewijn@indes.com> - 2017-06-14 09:54 +0200

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