Re: [lwip-devel] [bug #20254] Initializing static/global variables

[Jonathan Larmour]

Jonathan Larmour wrote:
> Goldschmidt Simon wrote:

> > Note that many pieces of embedded software that are supposed to be
> > ultra-portable provide compile switches whether to initialize the data
> > or not. I'll try to search for some C definition if the initialization
> > to zero is mandatory or not.
>
> It is mandatory.

I just noticed this is ambiguous - it's not clear what we're saying is 
doing the init to 0 :-). What is mandatory is that any static or global 
with no immediate initialiser must be initialised to 0 by the system before 
program startup. In practice, all such statics/globals, along with those 
that are explicitly initialised to 0, are placed in a .bss (possibly also 
.sbss for "small" items - long story) section by the linker, and so do not 
occupy space in the binary, but the loader will allocate space for it, and 
clear it to 0.

Jifl
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