Interpreting Map files

["Chris Holman" <chrish at owl dot co dot uk>]

I am trying to understand how a linker script for gnu ld.exe works so that I
can re-write it for the ecos configuration utility.
After reading the manual for LD I thought I had a reasonable understanding
of how it worked, until I came across the following.

A snippet of the linker file reads,

############# Linker file start
  USR_SP	= 0x00000000 ;
  SV_UNCACHE_SP	= 0xa0000000 ;
  SZ_ROM = 0 ;
  SZ_RAM = 0 ;

  /* The .text section is located at address passed in command line
e.g. -Ttext=0x40000000 */
  .text      :
  {
  _stext = .;
    *reset.o(.text_boot) /* Boot Section locate at first */
    *reset.o(.text) /* Boot Section locate at first */
  } =0
  ROM_START = ADDR(.text) ;
  ROM_OFFSET = ROM_START & 0x1fffffff ;
  SZ_ROM += SIZEOF(.text) ;

	/* place .text_mon in uncacheable area */
  .text_mon (SV_UNCACHE_SP + ROM_OFFSET + SZ_ROM) : AT (ROM_START + SZ_ROM)
  {
    *mainmon.o(.text_boot)
    *mainmon.o(.text)
############# Linker file end

The application is built and the equivalent section of the map file is
displayed below.

############# map file start
                0x00000000                USR_SP=0x0
                0xa0000000                SV_UNCACHE_SP=0xa0000000
                0x00000000                SZ_ROM=0x0
                0x00000000                SZ_RAM=0x0

.text           0x40000000      0x8bc
                0x40000000                _stext=.
 *reset.o(.text_boot)
 .text_boot     0x40000000      0x8bc /pie1.5/release/lib/reset.o
                0x40000065                start_up
                0x40000308                get_reset_info
                0x4000084b                scard_check
                0x400005ac                ram_acc_check
                0x400007e2                speed_check
                0x40000000                KNL_boot_boot
                0x4000012c                KNL_boot_post
                0x400003bc                set_ex_bus
                0x40000570                rom_acc_check
                0x400002f6                KNL_boot_dumphandler
                0x4000041e                set_opt_ex_bus
                0x40000010                fatal_vec
                0x40000360                set_bcu
                0x40000891                buserr_check
                0x4000071e                ack_check
                0x40000280                KNL_boot_nmihandler
                0x40000008                nmi_vec
                0x40000694                cs3_check
                0x40000362                set_heg
                0x40000755                cs_swap_check
 *reset.o(.text)
                0x40000000                ROM_START=ADDR(.text)
                0x00000000                ROM_OFFSET=(ROM_START&0x1fffffff)
                0x0004b244                SZ_ROM=(SZ_ROM+SIZEOF(.text))

.text_mon       0xa00008bc     0x1286 load address 0x4004a988
 *mainmon.o(.text_boot)
 .text_boot     0xa00008bc      0x21e /pie1.5/release/lib/boot.a(mainmon.o)
############# map file end

My confusion starts here.
1) Why is the last calculation of SZ_ROM not equal to (0 + 0x8bc)?
2) How is the load address for .text_mon arrived at? It doesn't seem to fit
with the calcualtion used.

I'm sure I'm missing something here?
Are there any good references or guides to interpreting the map file or how
the linker comes up with these addresses?

Regards,
Chris Holman

European Support Coordinator,
Panasonic OWL, 2 Anderson Place,
EDINBURGH, EH6 5NP

Tel: 0131 5611041
e-mail: chris.holman@owl.co.uk



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