RE: [avr-gcc-list] ATmega256x trampolines? (Was: Why is there1200bytes of zeroes in my code?)

[Eric Weddington]

Hi Björn,

>From your description, it sounds like -Wl,--relax should be used all the
time. Is there ever a case where it should *not* be used? Can it be used for
all architectures (avr2, avr3,...)?

If it can be used all the time, then I can add it to the Makefile Template
that gets distributed with WinAVR/MFile.

Thanks
Eric Weddington

> -----Original Message-----
> From: 
> address@hidden 
> [mailto:address@hidden
> org] On Behalf Of Haase Bjoern (PT-BEU/EMT)
> Sent: Wednesday, March 21, 2007 3:05 AM
> To: Erik Christiansen; Joerg Wunsch
> Cc: address@hidden
> Subject: AW: [avr-gcc-list] ATmega256x trampolines? (Was: Why 
> is there1200bytes of zeroes in my code?)
> 
> Hi, you could solve your problem by using -Wl,--relax . The 
> linker first starts with worst-case assumptions that imply 
> that it needs a trampoline for any function. 
> 
> The linker thus reserves the space for all possibly needed 
> trampolines and starts the application code behind the 
> trampolines. If it turns out that not all of the trampolines 
> are actually needed, this space remains reserved by default. 
> 
> The space is freed afterwards when using the linker relaxation.
> 
> Yours, 
> 
> Björn.
> 
> 
> -----Ursprüngliche Nachricht-----
> Von: 
> address@hidden 
> [mailto:address@hidden
> org] Im Auftrag von Erik Christiansen
> Gesendet: Mittwoch, 21. März 2007 09:42
> An: Joerg Wunsch
> Cc: address@hidden
> Betreff: Re: [avr-gcc-list] ATmega256x trampolines? (Was: Why 
> is there 1200bytes of zeroes in my code?)
> 
> On Wed, Mar 21, 2007 at 07:07:24AM +0100, Joerg Wunsch wrote:
> 
> > 
> > >  *fill*         0x000020f3        0x1 00=20
> > >                 0x000020f4                
> __trampolines_start =3D .=20
> > >  *(.trampolines)=20
> > >  .trampolines   0x000020f4        0x0 linker stubs=20
> > >  *(.trampolines*)=20
> > >                 0x000020f4                
> __trampolines_end =3D .=20
> > >  *(.jumptables)=20
> > >  *(.jumptables*)=20
> > 
> > Obviously, this is somehow related to the linker stubs, but the
> > question is how the space allocation is calculated.
> 
> Is it possible to invoke avr-gcc with "-Wl,-verbose" in the winavr
> environment, so the we can see the linker script being used? (It would
> be enlightening to see what it directs for these sections.)
> 
> Erik
> 
> 
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