Re: [avr-chat] Startup code.

[Robert von Knobloch]

On 22/09/10 17:49, Erik Christiansen wrote:
>> I just removed ,init1 & .init2 from the linker script and replaced it
>> with my own code in a new section.
> 
> That's not a really good idea. They're standard sections, the compiler
> wants to put the default initialisation code in there. And you can use
> that code as is. If empty, the sections are simply omitted. (You have
> seen that crttn13.o only has two of the ten.)
> 
>> Only small thing is, that if my code:
>> does not actually exist (e.g. comment it out, the linker does not throw
>> any kind of error (not even an incomprehensible one!!), the code is, of
>> course, missing from the output.
> 
> It is not an error for an input section to be empty. You probaly have
> more than half of .init0 - .init9 empty. What you've done is quite
> normal, except that it is much easier to place it in one of the existing
> .init sections. e.g. If you have a hardware init for a peripheral chip,
> and one for some code which uses it, you might put the former in .init3
> and the latter in .init4, to make sure the execute in the right order.
> (Can't think of a better example at this hour.)

Hi Erik,
I need to remove the code from .init2.
If I make an init2 section, the compiler includes my code but also adds
the default stack pointer setting (which I cannot have, for resaons
explained).
So, either I rewrite crttn13.o which means recompiling the toolchain to
be non-standard (for all projects), as it is itself compiled during the
install process, or I make a linker script which is then specific only
for those projects that require it.
Setting the stack in software is not an option if I want to achieve my
hardware-independant goal. (OK - not quite true, but the way I want to
go :-) ).
I see that you are right, it cannot be an error for no code to be
written - I could just as easly omit hw initialisation im my main() and
it wouldn't squawk - it just looks wrong in a c source to have a
function (although it isn't a function really) that you can comment out
and no one cares - wrong thinking on my part :-(
Again, many thanks,
Robert