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Re: arm-gcc: avoid calling other system functions

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Il 17/05/2018 15:27, Grant Edwards ha scritto:
> On 2018-05-17, pozz <pozzugno@gmail.com> wrote:
> 
>> I'm trying to put all ISRs in RAM[*]. Unfortunately, depending on
>> the code, arm-gcc could call some system functions that are located
>> in Flash.
> 
> By "system functions" do you mean gcc built-in functions from libgcc?

Yes, now I know those functions come from libgcc.


> Or functions from /usr/lib/*whatever*?
> 
>> For example, if I use a switch statement, the compiler calls a piece of
>> code of system libraries (that are in Flash) that use a table lookup to
>> manage the switch.
> 
> If you're talking about libgcc, that's not what most people mean when
> they refer to "system libraries".

Built-in functions is a better name?


>> Is it possible to force arm-gcc to avoid calling system functions
> 
> 
>> from ISRs, so it can be executed completely in RAM?
> 
> No, I don't think there's any way to prevent gcc from emitting calls
> to functions provided by libgcc.  However, you should be able to put
> the ISR code in a separate file and link it statically with libgcc,
> and then locate the resulting object file's code in RAM.

It seems complex.


> Alternatively, you could just manually tweak your linker script to
> place the specific libgcc functions used by your ISR functions in RAM.

Any help?

> 
>> [*] This is why I need to erase/write Flash memory and during these
>> operations the Flash can't be read and code in Flash can't be executed.
> 
> Using ISRs to program flash seems pretty strange...
> 

No, I need to serve interrupts *during* Flash erasing/writing. So the 
ISR code must be placed in RAM.

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Thread

arm-gcc: avoid calling other system functions pozz <pozzugno@gmail.com> - 2018-05-17 14:37 +0200
  Re: arm-gcc: avoid calling other system functions Grant Edwards <invalid@invalid.invalid> - 2018-05-17 13:27 +0000
    Re: arm-gcc: avoid calling other system functions pozz <pozzugno@gmail.com> - 2018-05-17 15:35 +0200
      Re: arm-gcc: avoid calling other system functions Grant Edwards <invalid@invalid.invalid> - 2018-05-17 14:18 +0000
        Re: arm-gcc: avoid calling other system functions David Brown <david.brown@hesbynett.no> - 2018-05-17 17:08 +0200
        Re: arm-gcc: avoid calling other system functions pozz <pozzugno@gmail.com> - 2018-05-18 08:47 +0200
  Re: arm-gcc: avoid calling other system functions pozz <pozzugno@gmail.com> - 2018-05-17 15:30 +0200
  Re: arm-gcc: avoid calling other system functions David Brown <david.brown@hesbynett.no> - 2018-05-17 17:06 +0200
    Re: arm-gcc: avoid calling other system functions pozz <pozzugno@gmail.com> - 2018-05-18 09:07 +0200
      Re: arm-gcc: avoid calling other system functions David Brown <david.brown@hesbynett.no> - 2018-05-18 09:51 +0200
        Re: arm-gcc: avoid calling other system functions pozz <pozzugno@gmail.com> - 2018-05-21 09:14 +0200
          Re: arm-gcc: avoid calling other system functions David Brown <david.brown@hesbynett.no> - 2018-05-21 12:50 +0200
        Re: arm-gcc: avoid calling other system functions Joe Chisolm <jchisolm6@earthlink.net> - 2018-05-21 10:15 -0500
          Re: arm-gcc: avoid calling other system functions David Brown <david.brown@hesbynett.no> - 2018-05-21 19:31 +0200
            Re: arm-gcc: avoid calling other system functions pozz <pozzugno@gmail.com> - 2018-05-22 09:05 +0200
              Re: arm-gcc: avoid calling other system functions David Brown <david.brown@hesbynett.no> - 2018-05-22 10:59 +0200
              Re: arm-gcc: avoid calling other system functions Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2018-05-22 15:24 +0300
                Re: arm-gcc: avoid calling other system functions pozz <pozzugno@gmail.com> - 2018-05-22 14:55 +0200
  Re: arm-gcc: avoid calling other system functions Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2018-05-18 12:41 +0300

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