/**
|
/**
|
* ion_noxram.lds -- Linker script file for ION project (with no RAM or cache)
|
* 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.
|
* WARNING: This script is no longer used by any makefile, to be removed or
|
|
* refactored.
|
*
|
*
|
* The ion cpu has separate buses for code and data (Harvard architecture) but
|
* The ion cpu has separate buses for code and data (Harvard architecture) and
|
* does not have caches by default. This linker script targets that 'bare'
|
* can be used with no cache. This linker script targets that 'bare'
|
* system configuration. It is meant for early testing and debugging.
|
* 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
|
* This script will split the object file in two areas so that they can be put
|
* in separate memory blocks:
|
* in separate memory blocks:
|
* 1.- Code area (text output section)
|
* 1.- Code area (text output section)
|
* 2.- Data area (sdata, data and bss output sections)
|
* 2.- Data area (sdata, data and bss output sections)
|
*
|
*
|
* Since data constants can't be reached from the code bus, constant data
|
* 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.
|
* (usually in section rodata) needs to be put in the same space as other data.
|
* This is the main purpose of this file.
|
* This is the main purpose of this file.
|
* Alternatively, we might jus implement a 3-port memory and leave all sections
|
* Alternatively, we might just implement a 3-port memory and leave all sections
|
* adjacent, but that would be too expensive (3-port memory would take about
|
* adjacent, but that would be too expensive (3-port memory would take about
|
* twice as many memory blocks for the same memory size).
|
* twice as many memory blocks for the same memory size).
|
*
|
*
|
* FIXME code and data RAM block sizes hardcoded
|
* FIXME code and data RAM block sizes hardcoded
|
* FIXME code and data start addresses hardcoded
|
* FIXME code and data start addresses hardcoded
|
*/
|
*/
|
/*
|
/*
|
# Known problems:
|
# Known problems:
|
#
|
#
|
# 1.- LINK PROBLEM IF FLAG '-G0' NOT USED
|
# 1.- LINK PROBLEM IF FLAG '-G0' NOT USED
|
# If flag '-G0' is not used on gcc, linker fails with 'relocation
|
# If flag '-G0' is not used on gcc, linker fails with 'relocation
|
# truncated to fit: R_MIPS_GPREL16' error message.
|
# truncated to fit: R_MIPS_GPREL16' error message.
|
# This only happens when you use global or static veriables, initialized
|
# This only happens when you use global or static veriables, initialized
|
# or not.
|
# or not.
|
# (See explaination in the project docs about $gp indexed addressing in
|
# (See explaination in the project docs about $gp indexed addressing in
|
# MIPS architectures and the -G0 flag).
|
# MIPS architectures and the -G0 flag).
|
#
|
#
|
# SUSPECTED CAUSE:
|
# SUSPECTED CAUSE:
|
# I'm sure there is something wrong with my linker script.
|
# 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
|
# 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
|
# a script so that we can split code and data (including read-only) to
|
# different sections (and later to different ram blocks).
|
# different sections (and later to different ram blocks).
|
#
|
#
|
# WORKAROUND:
|
# WORKAROUND:
|
# Use -G0 flag so that _gp indexing is disabled. There is a performance
|
# 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
|
# hit, though. In effect we're telling the compiler to NOT use $gp for
|
# indexed access to any global variables.
|
# indexed access to any global variables.
|
# This is only necessary for the 'bare' target (no external ram and no
|
# 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
|
# cache) and will have to be fixed for regular targets (by using a
|
# standard link script or fixing mine).
|
# standard link script or fixing mine).
|
|
|
*/
|
*/
|
|
|
|
|
/* Make sure the first linked file is ths startup code from boot.s */
|
/* 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) */
|
/* (We might put boot.o in the ld command line, BEFORE all other files) */
|
STARTUP(boot.o)
|
STARTUP(boot.o)
|
|
|
/* Default object output format is ELF big endian */
|
/* Default object output format is ELF big endian */
|
OUTPUT_FORMAT(elf32-big)
|
OUTPUT_FORMAT(elf32-big)
|
|
|
|
|
|
|
SECTIONS {
|
SECTIONS {
|
/* Put all code at CODE area */
|
/* Put all code at CODE area */
|
.text 0x00000000 : {
|
.text 0x00000000 : {
|
_ftext = . ;
|
_ftext = . ;
|
* (.text);
|
* (.text);
|
|
|
|
|
} = 0 /* fill gaps with zeros */
|
} = 0 /* fill gaps with zeros */
|
|
|
/* Mark end of executable code */
|
/* Mark end of executable code */
|
_ecode = .;
|
_ecode = .;
|
/* mark end of read-only code */
|
/* mark end of read-only code */
|
_etext = .;
|
_etext = .;
|
PROVIDE (etext = .);
|
PROVIDE (etext = .);
|
|
|
|
|
/**** Put all data, including read-only, at DATA area */
|
/**** Put all data, including read-only, at DATA area */
|
|
|
.data 0x80000000 : {
|
.data 0x80000000 : {
|
_fdata = . ;
|
_fdata = . ;
|
* (.data);
|
* (.data);
|
* (.data.*);
|
* (.data.*);
|
|
|
/* Conventionally, symbol _gp points to the middle of a 64K area at the
|
/* Conventionally, symbol _gp points to the middle of a 64K area at the
|
start of the sdata section ('small data section'). Register $gp is
|
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
|
loaded with _gp at program startup (in boot.s) so that data in that
|
area can be reached with just one instruction.
|
area can be reached with just one instruction.
|
Note that the compiler/assembler will put data in the sdata section
|
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).
|
only if it is small enough (see as/gcc docs, -G option and others).
|
FIXME this feature has not been tested.
|
FIXME this feature has not been tested.
|
*/
|
*/
|
_gp = . + 0x7ff0; /* 0x7ff0 -> middle of 64K area */
|
_gp = . + 0x7ff0; /* 0x7ff0 -> middle of 64K area */
|
*(.lit8);
|
*(.lit8);
|
*(.lit4);
|
*(.lit4);
|
*(.sdata);
|
*(.sdata);
|
*(.sbss);
|
*(.sbss);
|
*(.gnu.linkonce.s*);
|
*(.gnu.linkonce.s*);
|
*(.rodata);
|
*(.rodata);
|
*(.rodata.*);
|
*(.rodata.*);
|
/* mark end of initialised data */
|
/* mark end of initialised data */
|
_edata = .;
|
_edata = .;
|
PROVIDE (edata = .);
|
PROVIDE (edata = .);
|
|
|
/* start bss on dword boundary for easier clearing */
|
/* start bss on dword boundary for easier clearing */
|
. = ALIGN(8);
|
. = ALIGN(8);
|
|
|
}
|
}
|
|
|
/* start bss on dword boundary for easier clearing */
|
/* start bss on dword boundary for easier clearing */
|
. = ALIGN(8);
|
. = ALIGN(8);
|
|
|
/* mark start of uninitialised data */
|
/* mark start of uninitialised data */
|
__bss_start = .;
|
__bss_start = .;
|
_fbss = __bss_start;
|
_fbss = __bss_start;
|
|
|
.bss : {
|
.bss : {
|
/* *(.sbss); */
|
/* *(.sbss); */
|
*(.dynbss);
|
*(.dynbss);
|
*(COMMON);
|
*(COMMON);
|
* (.bss);
|
* (.bss);
|
_end = . ;
|
_end = . ;
|
}
|
}
|
/* mark end of uninitialised data */
|
/* mark end of uninitialised data */
|
_end = . ;
|
_end = . ;
|
PROVIDE (end = .);
|
PROVIDE (end = .);
|
}
|
}
|
|
|
