Xref: news2.mv.net comp.os.msdos.djgpp:6545
Newsgroups: comp.os.msdos.djgpp
From: hk AT bercos DOT de (Helge Kruse)
Subject: Re: __attribute__((section))
Reply-To: hk AT bercos DOT de
Organization: BERCOS GmbH Berlin, Germany
Message-ID: <DvBL0t.qp@bercos.de>
References: <Pine DOT NEB DOT 3 DOT 93 DOT 960726171833 DOT 18376B-100000 AT ananke DOT amu DOT edu DOT pl>
Date: Mon, 29 Jul 1996 19:34:04 GMT
Lines: 78
To: djgpp AT delorie DOT com
DJ-Gateway: from newsgroup comp.os.msdos.djgpp

Mark Habersack (grendel AT ananke DOT amu DOT edu DOT pl) wrote:

: For one moment I suspected that I cannot use __attribute__(section) because
: djgpp doesn't know how to switch data segments, which would be necessary to
: acces the data in other sections which are not in the same address
: space as BSS & DATA (but then it is only a matter of an entry in djgpp.ld,
: isn't it? Of course, it is not possible to specify any section by default in
: that script, but that should not impose any restrictions on the compiler
: itself) - is that the reason? 

If you like to look at a quick and dirty hack, here it is:
----- makefile -----
CC=gcc
DJGPP=c:/djgpp

sample: sample.o specdat.o
	ld -Tdjgpp.lnk -o $@ $(DJGPP)/lib/crt0.o -L$(DJGPP)/lib $^ -lgcc -lc -lgcc

sample.o: sample.c
    
specdat.o: specdat.c
	$(CC) -S $< -o $*.sx
	sed "s/\.data/.section MYDATA/" <$*.sx >$*.s
	$(CC) -c $*.s -o $@

show: sample
	objdump -h $<

clean:
	rm -f sample *.o *.s* *.bak
----- sample.c -----
#include "specdat.h"

int maindata;

void main(void)
{
    maindata=specdata;
}
----- specdat.h -----
extern int specdata;
----- specdat.c -----
#include "specdat.h"

/* ONLY use initialized data! */
/* uninitialized data goes to .bss and cannot be moved */
int specdata=0;

/* section attributes are not supported for this target 
int me __attribute ((section("MYDATA"))); */
----- djgpp.lnk -----
OUTPUT_FORMAT("coff-go32")
ENTRY(start)
SECTIONS
{
  .text : {
    *(.text)
    etext  =  . ; _etext = .;
    . = ALIGN(0x200); 
  }
  .data ALIGN(0x200) : {
    *(.data)
    *(.bss)
    edata  =  . ; _edata = .;
    . = ALIGN(0x200); 
  }
  MYDATA 0x1234 : {
    _mydata = . ;
    *(MYDATA)
    _emydata = . ;
  }
}
----- end -----

The djgpp.lnk is written from mind, so check it against the system file.

Regards,
	Helge