64bit bfd_vma vs 32bit address space in linker

[Andreas Schwab <schwab at suse dot de>]

What is the expected behaviour of the linker when dot advances past the
32 bit address space and bfd_vma is 64 bits?  Is this undefined, or
should the result wrap around as if bfd_vma is only 32 bits?  Note the
address of .text in the linker map below.

$ objdump --info
BFD header file version 2.13.90.0.18 20030121 (SuSE Linux)
elf32-i386
 (header little endian, data little endian)
  i386
a.out-i386-linux
 (header little endian, data little endian)
  i386
efi-app-ia32
 (header little endian, data little endian)
  i386
elf32-little
 (header little endian, data little endian)
  i386
elf32-big
 (header big endian, data big endian)
  i386
elf64-x86-64
 (header little endian, data little endian)
  i386
elf64-little
 (header little endian, data little endian)
  i386
elf64-big
 (header big endian, data big endian)
  i386
srec
 (header endianness unknown, data endianness unknown)
  i386
symbolsrec
 (header endianness unknown, data endianness unknown)
  i386
tekhex
 (header endianness unknown, data endianness unknown)
  i386
binary
 (header endianness unknown, data endianness unknown)
  i386
ihex
 (header endianness unknown, data endianness unknown)
  i386
trad-core
 (header endianness unknown, data endianness unknown)

               elf32-i386 a.out-i386-linux efi-app-ia32 elf32-little elf32-big 
          i386 elf32-i386 a.out-i386-linux efi-app-ia32 elf32-little elf32-big 

               elf64-x86-64 elf64-little elf64-big srec symbolsrec tekhex 
          i386 elf64-x86-64 elf64-little elf64-big srec symbolsrec tekhex 

               binary ihex trad-core 
          i386 binary ihex --------- 
$ cat rom.s
        .section ".rom.text"
        .code16
        .globl  _start
_start:
        cli

        .section ".reset"
        .code16
.globl  reset_vector
reset_vector:
        jmp     _start_offset
$ cat rom.lds
OUTPUT_FORMAT("elf32-i386", "elf32-i386", "elf32-i386")
OUTPUT_ARCH(i386)

ENTRY(_start)

_RAMBASE = 0x4000;
_ROMBASE = 0xffff0000;
_start_offset = _start & 0xffff;

TARGET(binary)
SECTIONS
{
        . = _ROMBASE;

        .rom . : {
                _rom = .;
                *(.rom.text);
                *(.rom.data);
                . = ALIGN(16);
                _erom = .;
        }

        /DISCARD/ : {
                *(.comment)
                *(.note)
        }
}

SECTIONS {
        _ROMTOP = (_ROMBASE >= 0xffff0000)? 0xfffffff0 : 0xffff0;
        . = _ROMTOP;
        .reset . : {
                *(.reset)
                . = 15 ;
                BYTE(0x00);
        } 
}
$ as rom.s -o rom.o
$ ld rom.o -T rom.lds -M
rom.o(.reset+0x1): In function `reset_vector':
: relocation truncated to fit: R_386_PC16 _start_offset

Memory Configuration

Name             Origin             Length             Attributes
*default*        0x0000000000000000 0xffffffffffffffff

Linker script and memory map

LOAD rom.o
                0x0000000000004000                _RAMBASE = 0x4000
                0x00000000ffff0000                _ROMBASE = 0xffff0000
                0x0000000000000000                _start_offset = (_start & 0xffff)
TARGET(binary)
                0x00000000ffff0000                . = _ROMBASE

.rom            0x00000000ffff0000       0x10
                0x00000000ffff0000                _rom = .
 *(.rom.text)
 .rom.text      0x00000000ffff0000        0x1 rom.o
                0x00000000ffff0000                _start
 *(.rom.data)
                0x00000000ffff0010                . = ALIGN (0x10)
 *fill*         0x00000000ffff0001 0x10000000f 00
                0x00000000ffff0010                _erom = .

/DISCARD/
 *(.comment)
 *(.note)
                0x00000000fffffff0                _ROMTOP = (_ROMBASE >= 0xffff0000)?0xfffffff0:0xffff0
                0x00000000fffffff0                . = _ROMTOP

.reset          0x00000000fffffff0       0x10
 *(.reset)
 .reset         0x00000000fffffff0        0x3 rom.o
                0x00000000fffffff0                reset_vector
                0x00000000ffffffff                . = 0xf
 *fill*         0x00000000fffffff3 0x10000000c 00
                0x00000000ffffffff        0x1 BYTE 0x0
OUTPUT(a.out elf32-i386)

.text           0x0000000100000000        0x0

.data           0x0000000100000000        0x0

.bss            0x0000000100000000        0x0


Andreas.

-- 
Andreas Schwab, SuSE Labs, schwab at suse dot de
SuSE Linux AG, Deutschherrnstr. 15-19, D-90429 Nürnberg
Key fingerprint = 58CA 54C7 6D53 942B 1756  01D3 44D5 214B 8276 4ED5
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