Re: [avr-gcc-list] reserve some RAM for bootloader

[Ned Konz]

On Wednesday 15 June 2005 5:19 pm, Torsten Mohr wrote:

> i'd like to have a bootloader and a normal application in an ATMega128
> and have the interrupt vectors in handled in the bootloader.
>
> The bootloader should catch some of the interrupts and forward the
> others to the application program.
>
> For this i'd like to reserve some RAM for the bootloader that the
> application should not use.

Remember that there is a switch in the processor itself to choose where the 
interrupt vectors are located (bootloader or main memory). You may not need 
RAM for this.

> Is it possible to just set the start address of .data to a higher value
> than normal for the application?  Would that be just sufficient?
>
> Do i also need to add the offset of 0x00800000?

I think the answer for this and some of the other questions being asked about 
bootloaders is: "write a new linker script". Especially if it's just for use 
with your own code.

You just have to work around the default section names used by the compiler.

There are 5 avr5.x* link scripts that come with avr-libc; these may provide 
some insight into what you can do with the linker.

-- 
Ned Konz
http://bike-nomad.com