I am trying to do a very simple exercise as shown below
- Compiler a simple C program using arm-none-eabi-gcc compiler for a Cortex-R5 MCU target.
- Link it with the respective linker file and create a executable so I can load it and debug.
What have I tried?
- I was able to successfully compiler the below C code using the below mentioned command
#include<stdio.h>
int main()
{
int a = 1;
for(int i=0;i<10;i++)
{
a++;
}
return 0;
}
gcc Command used - arm-none-eabi-gcc -mcpu=cortex-r5 -mthumb -mfloat-abi=hard -mfpu=vfpv3-d16 --specs=nosys.specs -ffunction-sections -fdata-sections -c main.c -o hi.o
This has properly created a object file.
Where am I stuck?
When I tried to use the below linker and link command I am receiving a warning where the vector table is improperly placed in the memory (It is placed in the 0x10260000 (RAM) instead of 0x0 where it has to be)
Linker command used - arm-none-eabi-gcc -mcpu=cortex-r5 -mthumb -mfloat-abi=hard -mfpu=vfpv3-d16 -Wl,-Map=output.map -Wl,-I/home/kowshik/ti/mcu_plus_sdk_am273x_08_05_00_24/source/kernel/nortos/lib/ -Wl,-Lnortos.am273x.r5f.ti-arm-clang.debug.lib -nostdlib -nostartfiles --specs=nosys.specs -T linker.ld hi.o -o hi.elf
Linker file used
/* This is the stack that is used by code running within main()
* In case of NORTOS,
* - This means all the code outside of ISR uses this stack
* In case of FreeRTOS
* - This means all the code until vTaskStartScheduler() is called in main()
* uses this stack.
* - After vTaskStartScheduler() each task created in FreeRTOS has its own stack
*/
__stack_size = 16384;
/* This is the heap size for malloc() API in NORTOS and FreeRTOS
* This is also the heap used by pvPortMalloc in FreeRTOS
*/
__heap_size = 32768;
ENTRY(_vectors)/* This is the entry of the application, _vector MUST be placed at starting address 0x0 */
/* This is the size of stack when R5 is in IRQ mode
* In NORTOS,
* - Here interrupt nesting is enabled
* - This is the stack used by ISRs registered as type IRQ
* In FreeRTOS,
* - Here interrupt nesting is disabled
* - This is stack that is used initially when an IRQ is received
* - But then the mode is switched to SVC mode and SVC stack is used for all user ISR callbacks
* - Hence in FreeRTOS, IRQ stack size is less and SVC stack size is more
*/
__IRQ_STACK_SIZE = 256;
/* This is the size of stack when R5 is in IRQ mode
* - In both NORTOS and FreeRTOS, nesting is disabled for FIQ
*/
__FIQ_STACK_SIZE = 256;
__SVC_STACK_SIZE = 4096; /* This is the size of stack when R5 is in SVC mode */
__ABORT_STACK_SIZE = 256; /* This is the size of stack when R5 is in ABORT mode */
__UNDEFINED_STACK_SIZE = 256; /* This is the size of stack when R5 is in UNDEF mode */
MEMORY
{
R5F_VECS : ORIGIN = 0x00000000, LENGTH = 0x00000040
R5F_TCMA : ORIGIN = 0x00000040, LENGTH = 0x00003FC0
R5F_TCMB : ORIGIN = 0x00080000, LENGTH = 0x00004000
/* when using multi-core application's i.e more than one R5F active, make sure
* this memory does not overlap with other R5F's
*/
MSS_L2 : ORIGIN = 0x10260000, LENGTH = 0x40000
/* This is typically used to hold data IO buffers from accelerators like CSI, HWA, DSP */
DSS_L3 : ORIGIN = 0x88000000, LENGTH = 0x00390000
/* shared memories that are used by RTOS/NORTOS cores */
/* On R5F,
* - make sure there are MPU entries which map below regions as non-cache
*/
USER_SHM_MEM : ORIGIN = 0x102E8000, LENGTH = 0x00004000
LOG_SHM_MEM : ORIGIN = 0x102EC000, LENGTH = 0x00004000
/* MSS mailbox memory is used as shared memory, we dont use bottom 32*6 bytes, since its used as SW queue by ipc_notify */
RTOS_NORTOS_IPC_SHM_MEM : ORIGIN = 0xC5000000, LENGTH = 0x1F40
MAILBOX_HSM : ORIGIN = 0x44000000, LENGTH = 0x000003CE
MAILBOX_R5F : ORIGIN = 0x44000400, LENGTH = 0x000003CE
}
SECTIONS
{
/* This has the R5F entry point and vector table, this MUST be at 0x0 */
.vectors :
{
KEEP(*(.vectors)) /* Keep the vectors section */
} > R5F_VECS
/* This is rest of code. This can be placed in MSS_L2 */
.text :
{
*(.text) /* Code resides here */
} > MSS_L2
/* This is rest of initialized data. This can be placed in MSS_L2 */
.rodata :
{
*(.rodata) /* Consts go here */
} > MSS_L2
/* This is rest of uninitialized data. This can be placed in MSS_L2 */
.data :
{
*(.data) /* Initialized globals and statics go here */
} > MSS_L2
/* This is where the uninitialized data goes */
.bss :
{
*(.bss) /* Uninitialized globals go here */
__bss_start__ = .; /* Symbol for BSS start address */
*(.sysmem) /* Malloc heap goes here */
*(.stack) /* Main stack goes here */
__bss_end__ = .; /* Symbol for BSS end address */
} > MSS_L2
/* This is where the stacks for different R5F modes go */
.irqstack :
{
. = ALIGN(8);
__IRQ_STACK_START = .;
BYTE(0); /* Reserve space for IRQ stack */
__IRQ_STACK_END = .; /* Symbol for IRQ stack end address */
}
.fiqstack :
{
. = ALIGN(8);
__FIQ_STACK_START = .;
BYTE(0); /* Reserve space for FIQ stack */
__FIQ_STACK_END = .; /* Symbol for FIQ stack end address */
}
.svcstack :
{
. = ALIGN(8);
__SVC_STACK_START = .;
BYTE(0); /* Reserve space for SVC stack */
__SVC_STACK_END = .; /* Symbol for SVC stack end address */
}
.abortstack :
{
. = ALIGN(8);
__ABORT_STACK_START = .;
BYTE(0); /* Reserve space for ABORT stack */
__ABORT_STACK_END = .; /* Symbol for ABORT stack end address */
}
.undefinedstack :
{
. = ALIGN(8);
__UNDEFINED_STACK_START = .;
BYTE(0); /* Reserve space for UNDEFINED stack */
__UNDEFINED_STACK_END = .; /* Symbol for UNDEFINED stack end address */
}
/* Sections needed for C++ projects */
.ARM.exidx :
{
*(.ARM.exidx) /* Needed for C++ exception handling */
} > MSS_L2
.init_array :
{
KEEP(*(SORT(.init_array.*))) /* Contains function pointers called before main */
} > MSS_L2
.fini_array :
{
KEEP(*(SORT(.fini_array.*))) /* Contains function pointers called after main */
} > MSS_L2
/* any data buffer needed to be put in L3 can be assigned this section name */
.bss.dss_l3 :
{
*(.bss.dss_l3)
} > DSS_L3
/* General purpose user shared memory, used in some examples */
.bss.user_shared_mem (NOLOAD) :
{
*(.bss.user_shared_mem)
} > USER_SHM_MEM
/* this is used when Debug log's to shared memory are enabled, else this is not used */
.bss.log_shared_mem (NOLOAD) :
{
*(.bss.log_shared_mem)
} > LOG_SHM_MEM
/* this is used only when IPC RPMessage is enabled, else this is not used */
.bss.ipc_vring_mem (NOLOAD) :
{
*(.bss.ipc_vring_mem)
} > RTOS_NORTOS_IPC_SHM_MEM
/* this is used only when Secure IPC is enabled */
.bss.sipc_hsm_queue_mem (NOLOAD) :
{
*(.bss.sipc_hsm_queue_mem)
} > MAILBOX_HSM
.bss.sipc_r5f_queue_mem (NOLOAD) :
{
*(.bss.sipc_r5f_queue_mem)
} > MAILBOX_R5F
}
Warning I received - warning: cannot find entry symbol _vectors; defaulting to 0000000010260000
I am using AM273x Texas Instrument's MCU, here's the link to Technial reference manual (TRM)
I also opened the map file generated by this command I still see no section is allocated to the vectors alone.
I can definitely assure that the _vectors symbol is defined properly in a file that is already present in the nortos.am273x.r5f.ti-arm-clang.debug.lib static library. I can provide more details about this if you require.
Please help me here to properly locate the vector table in the binary so I can run my applications properly.
