How do I use the m_data(SRAM_L portion) on the S32 mcu?

[建宽高]

The current environment MCU: S32K144 compilation environment: S32 IDE library version: 0.8.4.

When I used the link file to compile, I found that m_data was used very little, almost all using m_data_2, how can I use the m_data section, and the following is my link configuration file

/*
** ###################################################################
** Processor: S32K144 with 64 KB SRAM
** Compiler: GNU C Compiler
**
** Abstract:
** Linker file for the GNU C Compiler
**
** Copyright (c) 2015-2016 Freescale Semiconductor, Inc.
** Copyright 2017 NXP
** All rights reserved.
**
** THIS SOFTWARE IS PROVIDED BY NXP "AS IS" AND ANY EXPRESSED OR
** IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
** OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
** IN NO EVENT SHALL NXP OR ITS CONTRIBUTORS BE LIABLE FOR ANY DIRECT,
** INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
** (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
** SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
** HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
** STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
** IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
** THE POSSIBILITY OF SUCH DAMAGE.
**
** http: www.freescale.com
** mail: support@freescale.com
**
** ###################################################################
*/

/* Entry Point */
ENTRY(Reset_Handler)

HEAP_SIZE = DEFINED(__heap_size__) ? __heap_size__ : 0x00000400;
STACK_SIZE = DEFINED(__stack_size__) ? __stack_size__ : 0x00000400;

/* If symbol __flash_vector_table__=1 is defined at link time
* the interrupt vector will not be copied to RAM.
* Warning: Using the interrupt vector from Flash will not allow
* INT_SYS_InstallHandler because the section is Read Only.
*/
M_VECTOR_RAM_SIZE = DEFINED(__flash_vector_table__) ? 0x0 : 0x0400;

/* Specify the memory areas */
MEMORY
{
/* Flash */
m_interrupts (RX) : ORIGIN = 0x00000000, LENGTH = 0x00000400
m_flash_config (RX) : ORIGIN = 0x00000400, LENGTH = 0x00000010
m_text (RX) : ORIGIN = 0x00000410, LENGTH = 0x0007FBF0

/* SRAM_L */
m_data (RW) : ORIGIN = 0x1FFF8000, LENGTH = 0x00008000

/* SRAM_U */
m_data_2 (RW) : ORIGIN = 0x20000000, LENGTH = 0x00007000
}

/* Define output sections */
SECTIONS
{
/* The startup code goes first into internal flash */
.interrupts :
{
__VECTOR_TABLE = .;
. = ALIGN(4);
KEEP(*(.isr_vector)) /* Startup code */
. = ALIGN(4);
} > m_interrupts

.flash_config :
{
. = ALIGN(4);
KEEP(*(.FlashConfig)) /* Flash Configuration Field (FCF) */
. = ALIGN(4);
} > m_flash_config

/* The program code and other data goes into internal flash */
.text :
{
. = ALIGN(4);
*(.text) /* .text sections (code) */
*(.text*) /* .text* sections (code) */
*(.rodata) /* .rodata sections (constants, strings, etc.) */
*(.rodata*) /* .rodata* sections (constants, strings, etc.) */
*(.glue_7) /* glue arm to thumb code */
*(.glue_7t) /* glue thumb to arm code */
*(.eh_frame)
KEEP (*(.init))
KEEP (*(.fini))
. = ALIGN(4);
} > m_text

.ARM.extab :
{
*(.ARM.extab* .gnu.linkonce.armextab.*)
} > m_text

.ARM :
{
__exidx_start = .;
*(.ARM.exidx*)
__exidx_end = .;
} > m_text

.ctors :
{
__CTOR_LIST__ = .;
/* gcc uses crtbegin.o to find the start of
the constructors, so we make sure it is
first. Because this is a wildcard, it
doesn't matter if the user does not
actually link against crtbegin.o; the
linker won't look for a file to match a
wildcard. The wildcard also means that it
doesn't matter which directory crtbegin.o
is in. */
KEEP (*crtbegin.o(.ctors))
KEEP (*crtbegin?.o(.ctors))
/* We don't want to include the .ctor section from
from the crtend.o file until after the sorted ctors.
The .ctor section from the crtend file contains the
end of ctors marker and it must be last */
KEEP (*(EXCLUDE_FILE(*crtend?.o *crtend.o) .ctors))
KEEP (*(SORT(.ctors.*)))
KEEP (*(.ctors))
__CTOR_END__ = .;
} > m_text

.dtors :
{
__DTOR_LIST__ = .;
KEEP (*crtbegin.o(.dtors))
KEEP (*crtbegin?.o(.dtors))
KEEP (*(EXCLUDE_FILE(*crtend?.o *crtend.o) .dtors))
KEEP (*(SORT(.dtors.*)))
KEEP (*(.dtors))
__DTOR_END__ = .;
} > m_text

.preinit_array :
{
PROVIDE_HIDDEN (__preinit_array_start = .);
KEEP (*(.preinit_array*))
PROVIDE_HIDDEN (__preinit_array_end = .);
} > m_text

.init_array :
{
PROVIDE_HIDDEN (__init_array_start = .);
KEEP (*(SORT(.init_array.*)))
KEEP (*(.init_array*))
PROVIDE_HIDDEN (__init_array_end = .);
} > m_text

.fini_array :
{
PROVIDE_HIDDEN (__fini_array_start = .);
KEEP (*(SORT(.fini_array.*)))
KEEP (*(.fini_array*))
PROVIDE_HIDDEN (__fini_array_end = .);
} > m_text

__etext = .; /* Define a global symbol at end of code. */
__DATA_ROM = .; /* Symbol is used by startup for data initialization. */
.interrupts_ram :
{
. = ALIGN(4);
__VECTOR_RAM__ = .;
__interrupts_ram_start__ = .; /* Create a global symbol at data start. */
*(.m_interrupts_ram) /* This is a user defined section. */
. += M_VECTOR_RAM_SIZE;
. = ALIGN(4);
__interrupts_ram_end__ = .; /* Define a global symbol at data end. */
} > m_data

__VECTOR_RAM = DEFINED(__flash_vector_table__) ? ORIGIN(m_interrupts) : __VECTOR_RAM__ ;
__RAM_VECTOR_TABLE_SIZE = DEFINED(__flash_vector_table__) ? 0x0 : (__interrupts_ram_end__ - __interrupts_ram_start__) ;

.data : AT(__DATA_ROM)
{
. = ALIGN(4);
__DATA_RAM = .;
__data_start__ = .; /* Create a global symbol at data start. */
*(.data) /* .data sections */
*(.data*) /* .data* sections */
KEEP(*(.jcr*))
. = ALIGN(4);
__data_end__ = .; /* Define a global symbol at data end. */
} > m_data

__DATA_END = __DATA_ROM + (__data_end__ - __data_start__);
__CODE_ROM = __DATA_END; /* Symbol is used by code initialization. */
.code : AT(__CODE_ROM)
{
. = ALIGN(4);
__CODE_RAM = .;
__code_start__ = .; /* Create a global symbol at code start. */
*(.code_ram) /* Custom section for storing code in RAM */
. = ALIGN(4);
__code_end__ = .; /* Define a global symbol at code end. */
} > m_data

__CODE_END = __CODE_ROM + (__code_end__ - __code_start__);

/* Custom Section Block that can be used to place data at absolute address. */
/* Use __attribute__((section (".customSection"))) to place data here. */
.customSectionBlock ORIGIN(m_data_2) :
{
KEEP(*(.customSection)) /* Keep section even if not referenced. */
} > m_data_2

/* Uninitialized data section. */
.bss :
{
/* This is used by the startup in order to initialize the .bss section. */
. = ALIGN(4);
__BSS_START = .;
__bss_start__ = .;
*(.bss)
*(.bss*)
*(COMMON)
. = ALIGN(4);
__bss_end__ = .;
__BSS_END = .;
} > m_data_2

.heap :
{
. = ALIGN(8);
__end__ = .;
PROVIDE(end = .);
PROVIDE(_end = .);
PROVIDE(__end = .);
__HeapBase = .;
. += HEAP_SIZE;
__HeapLimit = .;
__heap_limit = .;
} > m_data_2

.stack :
{
. = ALIGN(8);
. += STACK_SIZE;
} > m_data_2

/* Initializes stack on the end of block */
__StackTop = ORIGIN(m_data_2) + LENGTH(m_data_2);
__StackLimit = __StackTop - STACK_SIZE;
PROVIDE(__stack = __StackTop);

.ARM.attributes 0 : { *(.ARM.attributes) }

ASSERT(__StackLimit >= __HeapLimit, "region m_data_2 overflowed with stack and heap")
}

[jiri_kral]

Hi, 

By default in m_data (SRAM_L) ends initialized global variables, copy of INT vector table and RAM_CODE. In m_data_2 ends .bss section (uninitialized global variables), stack and heap. 

If you need more RAM - you can merge m_data and m_data_2 section. Just remove m_data_2 section, extend m_data to 0xF000 size and replace all m_data_2 target to m_data in linker file.

Other possibility is force variables into m_data seciton by __attribute__ ((section(".data"))) int my_var

Jiri

[priyankb]

Hi Jiri,

Is it possible to place a large initialized char array into external SRAM. I have tried but reads garbage data.

Also tried placing whole file into external SRAM but got same result.

[建宽高]

3Q 

I changed it to the following configuration.?

/* SRAM */
m_data_2 (RW) : ORIGIN = 0x1FFF8000, LENGTH = 0x0000F000

[jiri_kral]

It should be okay. Make sure that all section targets are changed from m_data to m_data_2. 

Jiri