Re: [avr-gcc-list] Maximum Object File Alignment

[E. Weddington]

On 19 Nov 2002 at 10:06, Robert Latham wrote:

> I am trying to create a global array in program memory (flash) to
> which I wish to write using spm.   The array needs to be aligned to
> the flash pages.   So I have a declaration as follows:
> 
> __attribute__ ((progmem, aligned(128)))
> unsigned char gucArray[ARRAY_SIZE] =
> {
> <lots of bytes>
> };
> In response the compiler issues the warning:
> 
> "Warning: alignment of `gucArray' is greater than maximum object file
> alignment. Using 1."
> 

I tried it too and got the same thing.

An alternative solution, since you're putting the array in Flash, 
would be to give the variable a "section" attribute which puts the 
array in its own named section. Then in your linker flags you can 
relocate this named section to any address in the Flash.


<snip>

> Bruce's post did suggest one way out - creating the array in
> assembler. 
>   However, I can't find any *comprehensive* documentation of the gcc
> in-line assembler, so whilst I've figured out how to create in-line
> assembler functions, I've no idea how to create and reference (from C
> or in-line assembler functions) a global variable defined in
> assembler.   Can anyone point me in the right direction please?

GNU Manuals Online:
http://www.gnu.org/manual/

At this site, look for:
gas = GNU Assembler
ld = GNU Linker
gcc = GNU Compiler


HTH,
Eric
avr-gcc-list at http://avr1.org