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Re: [avr-gcc-list] fixed address for PROGMEM


From: Joerg Wunsch
Subject: Re: [avr-gcc-list] fixed address for PROGMEM
Date: Wed, 12 Nov 2003 18:26:48 +0100 (MET)

As Erik Christiansen <address@hidden> wrote:

>There may be relevant expertise on the list. I don't know if building
>gcc with "-fPIC" or "-fpic" is realistic for this target.

Not in the general case.  AVRs with <= 8 KB of ROM do use PC-relative
addressing anyway, but for devices with larger ROMs, it's impossible
to reach an arbitrary destination with a relative jump or call.  So I
figure it's not possible to implement PIC (position-independent code)
there.  (A completely self-contained library module could perhaps be
made position-independent, as long as it fits into this 8 KB limit.)

> Where would
>the shared library be loaded from?

Good question. ;-)  It has to be brought into ROM (Harvard
architecture), but newer AVRs can do self-programming.

> What would do the job of ld.so?

That must be part of the application.

-- 
J"org Wunsch                                           Unix support engineer
address@hidden        http://www.interface-systems.de/~j/


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