gcc: NOLOAD and .noinit

From	pozz <pozzugno@gmail.com>
Newsgroups	comp.arch.embedded
Subject	gcc: NOLOAD and .noinit
Date	2022-03-19 08:02 +0100
Organization	A noiseless patient Spider
Message-ID	<t13v61$b72$1@dont-email.me> (permalink)

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I usually don't touch linker script of my development system, sincerely 
I can't read every details of a linker script, so I'm in trouble now.

As explained in my previous post, I need to avoid zeroing a static big 
variable, because it is allocated in SDRAM and SDRAM isn't available 
when zeroing of bss sections (and initialization of data sections) occurs.

My development system allows me to use .noinit section, so I'm studying 
how it works.

MCUXpresso IDE generates complete linker scripts that automatically 
manages .noinit sections. These sections aren't added to section table 
that startup code reads to reset sections of RAM.

What I don't understand is the presence of NOLOAD directive in the 
linker script:

     [...]
     The linker will process the section normally, but will
     mark it so that a program loader will not load it into
     memory.

In embedded systems we don't have program loader, at least in my case 
there isn't any program loader. Code and constant variables are already 
at the right addresses at startup (Flash is already written). Only 
variables that changes at runtime must be initialized in RAM, but this 
is done by startup code, not by a program loader.

So, if startup code doesn't reset .noinit sections (because they aren't 
added in bss section table by the linker script), what's the exact 
purpose of NOLOAD directive?

I was tempted to remove NOLOAD directive from the linker script 
generated by MCUXpresso, but it re-generates it at every build.

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Thread

gcc: NOLOAD and .noinit pozz <pozzugno@gmail.com> - 2022-03-19 08:02 +0100
  Re: gcc: NOLOAD and .noinit David Brown <david.brown@hesbynett.no> - 2022-03-19 11:33 +0100
    Re: gcc: NOLOAD and .noinit pozz <pozzugno@gmail.com> - 2022-03-19 16:20 +0100
      Re: gcc: NOLOAD and .noinit David Brown <david.brown@hesbynett.no> - 2022-03-19 16:49 +0100
  Re: gcc: NOLOAD and .noinit Hans-Bernhard Bröker <HBBroeker@t-online.de> - 2022-03-19 12:46 +0100
    Re: gcc: NOLOAD and .noinit pozz <pozzugno@gmail.com> - 2022-03-19 16:27 +0100
      Re: gcc: NOLOAD and .noinit Tauno Voipio <tauno.voipio@notused.fi.invalid> - 2022-03-19 18:57 +0200
  Re: gcc: NOLOAD and .noinit kegs@provalid.com (Kent Dickey) - 2022-03-21 04:43 +0000

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