Linker file vector table for bootloader setup

1

I am currently trying to use a bootloader application created using MCUXPresso that requires that my application start address is located at 0x80000. According to the following documentation: enter image description here

However, the .bin I generate is created with Kinetis Design Studio (an earlier version of MCUXpresso) and does not have the option to modify the vector table in such an easy way as in MCUXPresso. What I've been trying is modifying the linker file manually doing the following:

ENTRY(Reset_Handler)

    /* Original Memory Map */
MEMORY
{
  m_interrupts          (RX)  : ORIGIN = 0x00000000, LENGTH = 0x00000400
  m_flash_config        (RX)  : ORIGIN = 0x00000400, LENGTH = 0x00000010
  m_text                (RX)  : ORIGIN = 0x00000410, LENGTH = 0x001FFBF0
  m_data                (RW)  : ORIGIN = 0x1FFF0000, LENGTH = 0x00030000
  m_data_2              (RW)  : ORIGIN = 0x20000000, LENGTH = 0x00030000
}

/* Modified Memory Map */

MEMORY
{
  m_interrupts          (RX)  : ORIGIN = 0x00080000, LENGTH = 0x00000400
  m_flash_config        (RX)  : ORIGIN = 0x00080400, LENGTH = 0x00000010
  m_text                (RX)  : ORIGIN = 0x00080410, LENGTH = 0x001FFBF0
  m_data                (RW)  : ORIGIN = 0x1FFF0000, LENGTH = 0x00030000
  m_data_2              (RW)  : ORIGIN = 0x20000000, LENGTH = 0x00030000
}

/* rest of linker file */
/* 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(__ram_vector_table__) ? __VECTOR_RAM__ : ORIGIN(m_interrupts);
  __RAM_VECTOR_TABLE_SIZE_BYTES = DEFINED(__ram_vector_table__) ? (__interrupts_ram_end__ - __interrupts_ram_start__) : 0x0;

  .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__);
  text_end = ORIGIN(m_text) + LENGTH(m_text);
  ASSERT(__DATA_END <= text_end, "region m_text overflowed with text and data")

  USB_RAM_GAP = DEFINED(__usb_ram_size__) ? __usb_ram_size__ : 0x800;
  /* Uninitialized data section */
  .bss :
  {
    /* This is used by the startup in order to initialize the .bss section */
    . = ALIGN(4);
    __START_BSS = .;
    __bss_start__ = .;
    *(.bss)
    *(.bss*)
    . = ALIGN(512);
    USB_RAM_START = .;
    . += USB_RAM_GAP;
    *(COMMON)
    . = ALIGN(4);
    __bss_end__ = .;
    __END_BSS = .;
  } > m_data

  .heap :
  {
    . = ALIGN(8);
    __end__ = .;
    PROVIDE(end = .);
    __HeapBase = .;
    . += HEAP_SIZE;
    __HeapLimit = .;
    __heap_limit = .; /* Add for _sbrk */
  } > m_data_2

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

  m_usb_bdt USB_RAM_START (NOLOAD) :
  {
    *(m_usb_bdt)
    USB_RAM_BDT_END = .;
  }

  m_usb_global USB_RAM_BDT_END (NOLOAD) :
  {
    *(m_usb_global)
  }

  /* 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")
}

With this implementation, the bootloader does not load the application and it restarts. I assume the error comes from an erroneous memory map in my .bin.

The memory map should comply with the following: enter image description here

The startup_XXX.s file im currently using:

    .syntax unified
    .arch armv7-m

    .section .isr_vector, "a"
    .align 2
    .globl __isr_vector
__isr_vector:
    .long   __StackTop                                      /* Top of Stack */
    .long   Reset_Handler                                   /* Reset Handler */
    .long   NMI_Handler                                     /* NMI Handler*/
    .long   HardFault_Handler                               /* Hard Fault Handler*/
    .long   MemManage_Handler                               /* MPU Fault Handler*/
    .long   BusFault_Handler                                /* Bus Fault Handler*/
    .long   UsageFault_Handler                              /* Usage Fault Handler*/
    .long   0                                               /* Reserved*/
    .long   0                                               /* Reserved*/
    .long   0                                               /* Reserved*/
    .long   0                                               /* Reserved*/
    .long   SVC_Handler                                     /* SVCall Handler*/
    .long   DebugMon_Handler                                /* Debug Monitor Handler*/
    .long   0                                               /* Reserved*/
    .long   PendSV_Handler                                  /* PendSV Handler*/
    .long   SysTick_Handler                                 /* SysTick Handler*/

                                                            /* External Interrupts*/
    .long   DMA0_DMA16_IRQHandler                           /* DMA Channel 0, 16 Transfer Complete*/
    .long   DMA1_DMA17_IRQHandler                           /* DMA Channel 1, 17 Transfer Complete*/
    .long   DMA2_DMA18_IRQHandler                           /* DMA Channel 2, 18 Transfer Complete*/
    .long   DMA3_DMA19_IRQHandler                           /* DMA Channel 3, 19 Transfer Complete*/
    .long   DMA4_DMA20_IRQHandler                           /* DMA Channel 4, 20 Transfer Complete*/
    .long   DMA5_DMA21_IRQHandler                           /* DMA Channel 5, 21 Transfer Complete*/
    .long   DMA6_DMA22_IRQHandler                           /* DMA Channel 6, 22 Transfer Complete*/
    .long   DMA7_DMA23_IRQHandler                           /* DMA Channel 7, 23 Transfer Complete*/
    .long   DMA8_DMA24_IRQHandler                           /* DMA Channel 8, 24 Transfer Complete*/
    .long   DMA9_DMA25_IRQHandler                           /* DMA Channel 9, 25 Transfer Complete*/
    .long   DMA10_DMA26_IRQHandler                          /* DMA Channel 10, 26 Transfer Complete*/
    .long   DMA11_DMA27_IRQHandler                          /* DMA Channel 11, 27 Transfer Complete*/
    .long   DMA12_DMA28_IRQHandler                          /* DMA Channel 12, 28 Transfer Complete*/
    .long   DMA13_DMA29_IRQHandler                          /* DMA Channel 13, 29 Transfer Complete*/
    .long   DMA14_DMA30_IRQHandler                          /* DMA Channel 14, 30 Transfer Complete*/
    .long   DMA15_DMA31_IRQHandler                          /* DMA Channel 15, 31 Transfer Complete*/
    .long   DMA_Error_IRQHandler                            /* DMA Error Interrupt*/
    .long   MCM_IRQHandler                                  /* Normal Interrupt*/
    .long   FTFE_IRQHandler                                 /* FTFE Command complete interrupt*/
    .long   Read_Collision_IRQHandler                       /* Read Collision Interrupt*/
    .long   LVD_LVW_IRQHandler                              /* Low Voltage Detect, Low Voltage Warning*/
    .long   LLWU_IRQHandler                                 /* Low Leakage Wakeup Unit*/
    .long   WDOG_EWM_IRQHandler                             /* WDOG Interrupt*/
    .long   RNG_IRQHandler                                  /* RNG Interrupt*/
    .long   I2C0_IRQHandler                                 /* I2C0 interrupt*/
    .long   I2C1_IRQHandler                                 /* I2C1 interrupt*/
    .long   SPI0_IRQHandler                                 /* SPI0 Interrupt*/
    .long   SPI1_IRQHandler                                 /* SPI1 Interrupt*/
    .long   I2S0_Tx_IRQHandler                              /* I2S0 transmit interrupt*/
    .long   I2S0_Rx_IRQHandler                              /* I2S0 receive interrupt*/
    .long   Reserved46_IRQHandler                           /* Reserved interrupt 46*/
    .long   UART0_RX_TX_IRQHandler                          /* UART0 Receive/Transmit interrupt*/
    .long   UART0_ERR_IRQHandler                            /* UART0 Error interrupt*/
    .long   UART1_RX_TX_IRQHandler                          /* UART1 Receive/Transmit interrupt*/
    .long   UART1_ERR_IRQHandler                            /* UART1 Error interrupt*/
    .long   UART2_RX_TX_IRQHandler                          /* UART2 Receive/Transmit interrupt*/
    .long   UART2_ERR_IRQHandler                            /* UART2 Error interrupt*/
    .long   UART3_RX_TX_IRQHandler                          /* UART3 Receive/Transmit interrupt*/
    .long   UART3_ERR_IRQHandler                            /* UART3 Error interrupt*/
    .long   ADC0_IRQHandler                                 /* ADC0 interrupt*/
    .long   CMP0_IRQHandler                                 /* CMP0 interrupt*/
    .long   CMP1_IRQHandler                                 /* CMP1 interrupt*/
    .long   FTM0_IRQHandler                                 /* FTM0 fault, overflow and channels interrupt*/
    .long   FTM1_IRQHandler                                 /* FTM1 fault, overflow and channels interrupt*/
    .long   FTM2_IRQHandler                                 /* FTM2 fault, overflow and channels interrupt*/
    .long   CMT_IRQHandler                                  /* CMT interrupt*/
    .long   RTC_IRQHandler                                  /* RTC interrupt*/
    .long   RTC_Seconds_IRQHandler                          /* RTC seconds interrupt*/
    .long   PIT0_IRQHandler                                 /* PIT timer channel 0 interrupt*/
    .long   PIT1_IRQHandler                                 /* PIT timer channel 1 interrupt*/
    .long   PIT2_IRQHandler                                 /* PIT timer channel 2 interrupt*/
    .long   PIT3_IRQHandler                                 /* PIT timer channel 3 interrupt*/
    .long   PDB0_IRQHandler                                 /* PDB0 Interrupt*/
    .long   USB0_IRQHandler                                 /* USB0 interrupt*/
    .long   USBDCD_IRQHandler                               /* USBDCD Interrupt*/
    .long   Reserved71_IRQHandler                           /* Reserved interrupt 71*/
    .long   DAC0_IRQHandler                                 /* DAC0 interrupt*/
    .long   MCG_IRQHandler                                  /* MCG Interrupt*/
    .long   LPTMR0_IRQHandler                               /* LPTimer interrupt*/
    .long   PORTA_IRQHandler                                /* Port A interrupt*/
    .long   PORTB_IRQHandler                                /* Port B interrupt*/
    .long   PORTC_IRQHandler                                /* Port C interrupt*/
    .long   PORTD_IRQHandler                                /* Port D interrupt*/
    .long   PORTE_IRQHandler                                /* Port E interrupt*/
    .long   SWI_IRQHandler                                  /* Software interrupt*/
    .long   SPI2_IRQHandler                                 /* SPI2 Interrupt*/
    .long   UART4_RX_TX_IRQHandler                          /* UART4 Receive/Transmit interrupt*/
    .long   UART4_ERR_IRQHandler                            /* UART4 Error interrupt*/
    .long   Reserved84_IRQHandler                           /* Reserved interrupt 84*/
    .long   Reserved85_IRQHandler                           /* Reserved interrupt 85*/
    .long   CMP2_IRQHandler                                 /* CMP2 interrupt*/
    .long   FTM3_IRQHandler                                 /* FTM3 fault, overflow and channels interrupt*/
    .long   DAC1_IRQHandler                                 /* DAC1 interrupt*/
    .long   ADC1_IRQHandler                                 /* ADC1 interrupt*/
    .long   I2C2_IRQHandler                                 /* I2C2 interrupt*/
    .long   CAN0_ORed_Message_buffer_IRQHandler             /* CAN0 OR'd message buffers interrupt*/
    .long   CAN0_Bus_Off_IRQHandler                         /* CAN0 bus off interrupt*/
    .long   CAN0_Error_IRQHandler                           /* CAN0 error interrupt*/
    .long   CAN0_Tx_Warning_IRQHandler                      /* CAN0 Tx warning interrupt*/
    .long   CAN0_Rx_Warning_IRQHandler                      /* CAN0 Rx warning interrupt*/
    .long   CAN0_Wake_Up_IRQHandler                         /* CAN0 wake up interrupt*/
    .long   SDHC_IRQHandler                                 /* SDHC interrupt*/
    .long   ENET_1588_Timer_IRQHandler                      /* Ethernet MAC IEEE 1588 Timer Interrupt*/
    .long   ENET_Transmit_IRQHandler                        /* Ethernet MAC Transmit Interrupt*/
    .long   ENET_Receive_IRQHandler                         /* Ethernet MAC Receive Interrupt*/
    .long   ENET_Error_IRQHandler                           /* Ethernet MAC Error and miscelaneous Interrupt*/
    .long   LPUART0_IRQHandler                              /* LPUART0 status/error interrupt*/
    .long   TSI0_IRQHandler                                 /* TSI0 interrupt*/
    .long   TPM1_IRQHandler                                 /* TPM1 fault, overflow and channels interrupt*/
    .long   TPM2_IRQHandler                                 /* TPM2 fault, overflow and channels interrupt*/
    .long   USBHSDCD_IRQHandler                             /* USBHSDCD, USBHS Phy Interrupt*/
    .long   I2C3_IRQHandler                                 /* I2C3 interrupt*/
    .long   CMP3_IRQHandler                                 /* CMP3 interrupt*/
    .long   USBHS_IRQHandler                                /* USB high speed OTG interrupt*/
    .long   CAN1_ORed_Message_buffer_IRQHandler             /* CAN1 OR'd message buffers interrupt*/
    .long   CAN1_Bus_Off_IRQHandler                         /* CAN1 bus off interrupt*/
    .long   CAN1_Error_IRQHandler                           /* CAN1 error interrupt*/
    .long   CAN1_Tx_Warning_IRQHandler                      /* CAN1 Tx warning interrupt*/
    .long   CAN1_Rx_Warning_IRQHandler                      /* CAN1 Rx warning interrupt*/
    .long   CAN1_Wake_Up_IRQHandler                         /* CAN1 wake up interrupt*/
    .long   DefaultISR                                      /* 116*/
    .long   DefaultISR                                      /* 117*/
    .long   DefaultISR                                      /* 118*/
    .long   DefaultISR                                      /* 119*/
    .long   DefaultISR                                      /* 120*/
    .long   DefaultISR                                      /* 121*/
    .long   DefaultISR                                      /* 122*/
    .long   DefaultISR                                      /* 123*/
    .long   DefaultISR                                      /* 124*/
    .long   DefaultISR                                      /* 125*/
    (...)
    .long   DefaultISR                                      /* 245*/
    .long   DefaultISR                                      /* 246*/
    .long   DefaultISR                                      /* 247*/
    .long   DefaultISR                                      /* 248*/
    .long   DefaultISR                                      /* 249*/
    .long   DefaultISR                                      /* 250*/
    .long   DefaultISR                                      /* 251*/
    .long   DefaultISR                                      /* 252*/
    .long   DefaultISR                                      /* 253*/
    .long   DefaultISR                                      /* 254*/
    .long   0xFFFFFFFF                                      /*  Reserved for user TRIM value*/

    .size    __isr_vector, . - __isr_vector

/* Flash Configuration */
    .section .FlashConfig, "a"
    .long 0xFFFFFFFF
    .long 0xFFFFFFFF
    .long 0xFFFFFFFF
    .long 0xFFFFFFFE

    .text
    .thumb

/* Reset Handler */

    .thumb_func
    .align 2
    .globl   Reset_Handler
    .weak    Reset_Handler
    .type    Reset_Handler, %function
Reset_Handler:
    cpsid   i               /* Mask interrupts */
    .equ    VTOR, 0xE000ED08
    ldr     r0, =VTOR
    ldr     r1, =__isr_vector
    str     r1, [r0]
    ldr     r2, [r1]
    msr     msp, r2
#ifndef __NO_SYSTEM_INIT
    ldr   r0,=SystemInit
    blx   r0
#endif
/*     Loop to copy data from read only memory to RAM. The ranges
 *      of copy from/to are specified by following symbols evaluated in
 *      linker script.
 *      __etext: End of code section, i.e., begin of data sections to copy from.
 *      __data_start__/__data_end__: RAM address range that data should be
 *      copied to. Both must be aligned to 4 bytes boundary.  */

    ldr    r1, =__etext
    ldr    r2, =__data_start__
    ldr    r3, =__data_end__

#if 1
/* Here are two copies of loop implemenations. First one favors code size
 * and the second one favors performance. Default uses the first one.
 * Change to "#if 0" to use the second one */
.LC0:
    cmp     r2, r3
    ittt    lt
    ldrlt   r0, [r1], #4
    strlt   r0, [r2], #4
    blt    .LC0
#else
    subs    r3, r2
    ble    .LC1
.LC0:
    subs    r3, #4
    ldr    r0, [r1, r3]
    str    r0, [r2, r3]
    bgt    .LC0
.LC1:
#endif

#ifdef __STARTUP_CLEAR_BSS
/*     This part of work usually is done in C library startup code. Otherwise,
 *     define this macro to enable it in this startup.
 *
 *     Loop to zero out BSS section, which uses following symbols
 *     in linker script:
 *      __bss_start__: start of BSS section. Must align to 4
 *      __bss_end__: end of BSS section. Must align to 4
 */
    ldr r1, =__bss_start__
    ldr r2, =__bss_end__

    movs    r0, 0
.LC2:
    cmp     r1, r2
    itt    lt
    strlt   r0, [r1], #4
    blt    .LC2
#endif /* __STARTUP_CLEAR_BSS */

    cpsie   i               /* Unmask interrupts */
#ifndef __START
#define __START _start
#endif
#ifndef __ATOLLIC__
    ldr   r0,=__START
    blx   r0
#else
    ldr   r0,=__libc_init_array
    blx   r0
    ldr   r0,=main
    bx    r0
#endif
    .pool

[Could not paste the whole file]

My attempt to solve the issue comes from this tutorial.

c
embedded
microcontroller
linker-scripts
asked on Stack Overflow Nov 5, 2019 by A. San • edited Nov 6, 2019 by A. San

2 Answers

1

You should place the startup function in the position 0x80000, so the bootloader can execute it correctly.

Another problem are the interrupts. Since you have a bootloader, and I guess it is running the entire program life, you should not replace its interrupt vector. The bootloader probably have some functions to set the interrupts, so you should use those, instead of relocating the ISR vector.


Placing the startup function at a known address:

Since you are using the MCUXpresso and the KDS, I supose you are using the toolchain provided by NXP, based in GCC.

If so, you will need to use sections in order to set a function at a defined address. In the SDK, the startup function is located in the file startup_XXX.S, and in my file (I don't know if they use always the same naming) it is called Reset_Handler. You can find it also from your ISR vector, being it the second entry (the reset entry).

In my case, it is defined as follows:

.section .reset_handler_section, "a"  //EDIT 3: This is the line added
.thumb_func
    .align 2
    .globl   Reset_Handler
    .weak    Reset_Handler
    .type    Reset_Handler, %function
Reset_Handler:
    //Actual reset code follows

You should have something similar in your ASM code.

Now, once you know which is your startup function, you should place it at 0x80000. This is done in your linker file, in the SECTIONS section.

But first, your new memory map should only include the memory which you are allowed to modify, this is the section called "Application Area" in the image you attached.

So, the memory map for our application should be:

MEMORY
{
  m_text                (RX)  : ORIGIN = 0x00080000, LENGTH = 0x00080000
  m_data                (RWX)  : ORIGIN = 0x20000000, LENGTH = 0x00030000
}

WARNING: You should know where your data (m_data) can start in RAM, since you don't want to override the bootloader data. You didn't show it in your image, so I just picked an ORIGIN in RAM, but you should check this.

Note also that there are no interrupts nor flash_config sections. I presume that the bootloader already have those, so you don't need to add them again.

Once you have defined your memory map, you can add all your program to it:

SECTIONS
{
  /* The startup code*/
    .startup_text :
  {
    . = ALIGN(4);
    KEEP(*(.reset_handler_section)) /* Startup data */ /*EDIT 3: This is the modification*/
    KEEP(*(.isr_vector))     /* EDIT 6: Startup code. It is needed in order to avoid modifying source files. It is not used, since the reset vector is the defined in the Bootloader build */
    *(.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 */
    KEEP (*(.init))  /*EDIT 2: The init section. If there are more 
                      * sections like this, just keep adding them here.
                      */
  } > m_text

    /*EDIT 5. Added entire section*/
  .ARM :
  {
    __exidx_start = .;
    *(.ARM.exidx*)
    __exidx_end = .;
  } > m_text

  __DATA_ROM = .;          /* Symbol is used by startup for data initialization */ /*EDIT 7: This symbol must be placed at the end of the text sections, so the data can follow all the code in ROM*/
  __etext = .;    /* define a global symbol at end of code */ /*EDIT 4*/

  /*The application variables and other data in RAM*/
  .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*))
    KEEP(*(.ramSection))
    . = ALIGN(4);
    __data_end__ = .;        /* define a global symbol at data end */
  } > m_data

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

}

As a little explanation, we are telling the linker to place all inside the section ".startup_text" (this can be any name) into the m_text memory, always in order. So, in the first address of m_text (this is, 0x80000) it will place the Reset_Handler. After it, it will place all the other functions (.text) and the constant data (rodata).

We also define the symbol __DATA_ROM to be in the last address of the section. After all the constant data, we also append the initialised data. This data has constant values that will go in ROM, but the linker should also reserve memory for them in RAM, in order to be able to modify them. This is what is done in the data section.


Edit 1: For the linker to know where to start your program, thus being able to look what code will be needed, you have to tell it which one is the startup point of your program, since the linker does not understands about chip specific hardware (like reset vector entry). This is done by adding this to the beginning of the linker file, before the MEMORY section:

/* Entry Point */
ENTRY(Reset_Handler)

STACK_SIZE = 0x0400;
M_VECTOR_RAM_SIZE = 0x0400;

I don't know if the size's definitions are really required, but just in case I put them also here.

answered on Stack Overflow Nov 5, 2019 by LoPiTaL • edited Nov 6, 2019 by LoPiTaL
0

Adding to the solution:

The modification on the linker file in my question was indeed correct.

MEMORY
{
  m_interrupts          (RX)  : ORIGIN = 0x00080000, LENGTH = 0x00000400
  m_flash_config        (RX)  : ORIGIN = 0x00080400, LENGTH = 0x00000010
  m_text                (RX)  : ORIGIN = 0x00080410, LENGTH = 0x001FFBF0
  m_data                (RW)  : ORIGIN = 0x1FFF0000, LENGTH = 0x00030000
  m_data_2              (RW)  : ORIGIN = 0x20000000, LENGTH = 0x00030000
}

The problem of not loading the program came from the fact that it runs a real time operating system. Therefore I later realized that the solution to my problem was not on the linker file but in restarting the SysTick clock which seemed to affect the RTOS and therefore it did not start the loaded application.

If you are using a real time operating system, make sure to reset the system clock before loading the application from the bootloader. This seemed to solve my issues.

However, the proposed solution to the linker file does work but the problem came from a different source.

answered on Stack Overflow Nov 11, 2019 by A. San

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