Re: Cortex-M: share an int between two tasks

From	David Brown <david.brown@hesbynett.no>
Newsgroups	comp.arch.embedded
Subject	Re: Cortex-M: share an int between two tasks
Date	2020-03-30 16:07 +0200
Organization	A noiseless patient Spider
Message-ID	<r5suft$3e9$1@dont-email.me> (permalink)
References	(3 earlier) <_ITdG.1110033$Gh7.201179@fx45.iad> <r59qsb$ll2$1@dont-email.me> <Ax1eG.523780$ls7.59106@fx40.iad> <r5ad5k$574$1@dont-email.me> <IdweG.1169345$Gh7.768707@fx45.iad>

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On 24/03/2020 23:55, Clifford Heath wrote:
> On 24/3/20 12:21 am, David Brown wrote:
>> Instructions like "dmb" force an order on the cpu operations, not the 
>> compiler - while "volatile" enforces a partial order on the compiler, 
>> but not the hardware.
>>
>> The standard solution would be asm("dmb" ::: "memory"), where the 
>> memory clobber forces an ordering on the compiler - and thus you can 
>> (usually) omit the "volatile".
> David, if you have time, many of us would appreciate a quick summary of 
> the situations where the different barriers should be used.
> 
> "dmb" can be a full read/write barrier, or just a write barrier. When to 
> use each?
> 
> "dsb" is different from "dmb" because it limits instruction ordering, 
> but when is that useful? When to use it as a write-only barrier?
> 
> "isb" is intended to precede a context switch, i.e. task switching in an 
> RTOS. Is it sufficient for that, and is that the only time to use it?
> 
> If you know a good article that gives practical guidelines, post a link, 
> otherwise I'd really like to hear your thoughts.
> 
> Clifford Heath.

Thread

Cortex-M: share an int between two tasks pozz <pozzugno@gmail.com> - 2020-03-13 15:38 +0100
  Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-13 17:49 +0100
    Re: Cortex-M: share an int between two tasks pozz <pozzugno@gmail.com> - 2020-03-18 09:09 +0100
      Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-18 09:17 +0100
      Re: Cortex-M: share an int between two tasks Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2020-03-18 17:37 +0100
        Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-18 19:23 +0100
    Re: Cortex-M: share an int between two tasks Les Cargill <lcargill99@comcast.com> - 2020-03-22 13:42 -0500
      Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-22 21:45 +0100
      Re: Cortex-M: share an int between two tasks Richard Damon <Richard@Damon-Family.org> - 2020-03-22 20:50 -0400
        Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-23 09:09 +0100
          Re: Cortex-M: share an int between two tasks Richard Damon <Richard@Damon-Family.org> - 2020-03-23 08:00 -0400
            Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-23 14:21 +0100
              Re: Cortex-M: share an int between two tasks Clifford Heath <no.spam@please.net> - 2020-03-25 09:55 +1100
                Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-30 16:07 +0200
                Re: Cortex-M: share an int between two tasks Clifford Heath <no.spam@please.net> - 2020-03-31 09:02 +1100
                Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-31 10:57 +0200
                Re: Cortex-M: share an int between two tasks Clifford Heath <no.spam@please.net> - 2020-04-01 12:05 +1100
                Re: Cortex-M: share an int between two tasks Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2020-03-30 17:49 +0300
                Re: Cortex-M: share an int between two tasks kegs@provalid.com (Kent Dickey) - 2020-05-19 00:34 -0500
                Re: Cortex-M: share an int between two tasks Clifford Heath <no.spam@please.net> - 2020-05-19 17:40 +1000
                Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-05-19 12:00 +0200
                Re: Cortex-M: share an int between two tasks Tom Gardner <spamjunk@blueyonder.co.uk> - 2020-05-19 13:48 +0100
  Re: Cortex-M: share an int between two tasks pozz <pozzugno@gmail.com> - 2020-03-18 09:20 +0100
    Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-18 10:06 +0100
      Re: Cortex-M: share an int between two tasks pozz <pozzugno@gmail.com> - 2020-03-18 10:59 +0100
        Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-18 11:48 +0100
          Re: Cortex-M: share an int between two tasks upsidedown@downunder.com - 2020-03-18 20:37 +0200
            Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-18 21:24 +0100
              Re: Cortex-M: share an int between two tasks Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2020-03-19 14:05 +0200
                Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-19 13:16 +0100
                Re: Cortex-M: share an int between two tasks Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2020-03-19 14:27 +0200
                Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-19 14:13 +0100
            Re: Cortex-M: share an int between two tasks pozz <pozzugno@gmail.com> - 2020-03-19 08:03 +0100
              Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-19 09:10 +0100
              Re: Cortex-M: share an int between two tasks upsidedown@downunder.com - 2020-03-19 12:51 +0200
          Re: Cortex-M: share an int between two tasks pozz <pozzugno@gmail.com> - 2020-03-19 07:40 +0100
            Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-19 09:38 +0100
              Re: Cortex-M: share an int between two tasks pozz <pozzugno@gmail.com> - 2020-03-19 11:26 +0100
                Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-19 12:12 +0100
                Re: Cortex-M: share an int between two tasks pozz <pozzugno@gmail.com> - 2020-03-19 15:31 +0100
                Re: Cortex-M: share an int between two tasks pozz <pozzugno@gmail.com> - 2020-03-23 09:22 +0100
                Re: Cortex-M: share an int between two tasks Richard Damon <Richard@Damon-Family.org> - 2020-03-23 08:10 -0400
                Re: Cortex-M: share an int between two tasks pozz <pozzugno@gmail.com> - 2020-03-23 13:47 +0100
                Re: Cortex-M: share an int between two tasks David Brown <david.brown@hesbynett.no> - 2020-03-23 14:31 +0100
                Re: Cortex-M: share an int between two tasks Richard Damon <Richard@Damon-Family.org> - 2020-03-23 13:50 -0400
            Re: Cortex-M: share an int between two tasks Niklas Holsti <niklas.holsti@tidorum.invalid> - 2020-03-19 12:27 +0200
              Re: Cortex-M: share an int between two tasks pozz <pozzugno@gmail.com> - 2020-03-19 11:45 +0100
                Re: Cortex-M: share an int between two tasks upsidedown@downunder.com - 2020-03-19 13:27 +0200
    Re: Cortex-M: share an int between two tasks antispam@math.uni.wroc.pl - 2020-03-18 16:24 +0000

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