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/**

* ion_noxram.lds -- Linker script file for ION project (with no RAM or cache)

*

* WARNING: This script is no longer used by any makefile, to be removed.

*

* The ion cpu has separate buses for code and data (Harvard architecture) but

* does not have caches by default. This linker script targets that 'bare'

* system configuration. It is meant for early testing and debugging.

*

* This script will split the object file in two areas so that they can be put

* in separate memory blocks:

* 1.- Code area (text output section)

* 2.- Data area (sdata, data and bss output sections)

*

* Since data constants can't be reached from the code bus, constant data

* (usually in section rodata) needs to be put in the same space as other data.

* This is the main purpose of this file.

* Alternatively, we might jus implement a 3-port memory and leave all sections

* adjacent, but that would be too expensive (3-port memory would take about

* twice as many memory blocks for the same memory size).

*

* FIXME code and data RAM block sizes hardcoded

* FIXME code and data start addresses hardcoded

*/

/*

# Known problems:

#

# 1.- LINK PROBLEM IF FLAG '-G0' NOT USED

#       If flag '-G0' is not used on gcc, linker fails with 'relocation

#       truncated to fit: R_MIPS_GPREL16' error message.

#       This only happens when you use global or static veriables, initialized

#       or not.

#       (See explaination in the project docs about $gp indexed addressing in

#       MIPS architectures and the -G0 flag).

#

#     SUSPECTED CAUSE:

#       I'm sure there is something wrong with my linker script.

#       With the default link scripts this does not happen. Yet we need to use

#       a script so that we can split code and data (including read-only) to

#       different sections (and later to different ram blocks).

#

#     WORKAROUND:

#       Use -G0 flag so that _gp indexing is disabled. There is a performance

#       hit, though. In effect we're telling the compiler to NOT use $gp for

#       indexed access to any global variables.

#       This is only necessary for the 'bare' target (no external ram and no

#       cache) and will have to be fixed for regular targets (by using a

#       standard link script or fixing mine).

*/

/* Make sure the first linked file is ths startup code from boot.s */

/* (We might put boot.o in the ld command line, BEFORE all other files) */

STARTUP(boot.o)

/* Default object output format is ELF big endian */

OUTPUT_FORMAT(elf32-big)

SECTIONS {

    /* Put all code at CODE area */

    .text 0x00000000 : {

        _ftext = . ;

        * (.text);

    } = 0 /* fill gaps with zeros */

    /* Mark end of executable code */

    _ecode = .;

    /* mark end of read-only code */

    _etext = .;

    PROVIDE (etext = .);

    /**** Put all data, including read-only, at DATA area */

    .data 0x80000000 : {

        _fdata = . ;

        * (.data);

        * (.data.*);

        /* Conventionally, symbol _gp points to the middle of a 64K area at the

           start of the sdata section ('small data section'). Register $gp is

           loaded with _gp at program startup (in boot.s) so that data in that

           area can be reached with just one instruction.

           Note that the compiler/assembler will put data in the sdata section

           only if it is small enough (see as/gcc docs, -G option and others).

           FIXME this feature has not been tested.

        */

        _gp = . + 0x7ff0; /* 0x7ff0 -> middle of 64K area */

        *(.lit8);

        *(.lit4);

        *(.sdata);

        *(.sbss);

        *(.gnu.linkonce.s*);

        *(.rodata);

        *(.rodata.*);

        /* mark end of initialised data */

        _edata  =  .;

        PROVIDE (edata = .);

        /* start bss on dword boundary for easier clearing */

        . = ALIGN(8);

    }

    /* start bss on dword boundary for easier clearing */

    . = ALIGN(8);

    /* mark start of uninitialised data */

    __bss_start = .;

    _fbss = __bss_start;

    .bss : {

        /* *(.sbss); */

        *(.dynbss);

        *(COMMON);

        * (.bss);

        _end = . ;

    }

    /* mark end of uninitialised data */

    _end = . ;

    PROVIDE (end = .);

}