[En-Nut-Discussion] Can't correctly build NutOS 4.8.9 on Fedora 14 for Ethernut 2.1b

Bernard Fouché bernard.fouche at kuantic.com
Wed Apr 20 17:20:57 CEST 2011

Hi Harald,

Le 19/04/2011 18:50, Harald Kipp a écrit :
> The fix will be available in 4.8.10. Not sure, when this will become
> available. There are a few more things waiting.
I suggest to add also "-mcall-prologues" in the default avr-gcc flags 
provided: compiling NutOS and my application with this option, I was 
able to spare about 3KB. There is no problem if some part of the code is 
compiled with or without this option since the 'prologues' require some 
code added at link time if needed. There is a very slight execution 
penalty because the pop/push are not done directly but in a function, 
but the flash spared is a big win (I was over 124K on the Ethernut 2.1b 
and I have a 4K booloader).

When link-time-optimization (LTO) will be considered fully operationnal 
(I'm waiting for Avr Studio 5 to change to the 'final' state and then 
consider the patches provided by Atmel in the avr compilation chain), 
there should be also memory to spare. Some says LTO already works 
correctly but I did not have time to test on my side. Maybe the ARM 
targets already use it?

Another suggestion is also to use 'CFLAGS' instead of 'CPFLAGS' in the 
Makefile(s) since the first one is the variable everyone knows about.

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