Re: [avr-gcc-list] [Patch, avr] Shrink interrupt vector table down to last used entry

[Georg-Johann Lay]

Senthil Kumar Selvaraj wrote:

>> Granted, the (saved memory) reward for the effort is small, but if the
>> user would specify the number of the highest used vector, then gas
>> conditional assembly, in a "bad vector" macro does handle the task:
> 
> Ah, but right now, the vector table is defined in avr-libc
> (crt1/gcrt1.S) and gets built into crtxxx.o at avr-libc build time. It
> is then linked into the final executable automatically by the gcc
> driver. I guess that rules out conditional assembly?

It is reasonable that gcrt1.S is contained in a distribution so that users can
assemble an use it directly.  There's already an issue for this: #38125.

http://savannah.nongnu.org/bugs/?38125

With that, it's straight forward to accomplish a small vector table:

Just -nostartfiles, add gcrt1.S to the project and define _VECTORS_SIZE.

That way it is flexible and freely adjustable without binutils hacks.

Johann