TMS320F28384S: CM - .vtable RAM section in generated output file

Are you not using vtable at all? OR are you using the vtable but wondering why it is appearing in hex file? Note that RAM vector table is also defined in the CM interrupt driver. This enables registering interrupts at runtime. If you are not using registerHandler functions, vtable should not be included in the build at all

Regards,

Veena

Hello Veena,
I use vtable and I register a couple of ISR:

Interrupt_registerHandler(FAULT_NMI, NMIHandler)
Interrupt_registerHandler(FAULT_SYSTICK, TickHandler)

As the bootloader runs in RAM a have enabled the vectorTableRAM[] definition, by eliminating the _FLASH preprocessor symbol, and I have set the vector table address accordling:

#ifdef _FLASH
#pragma RETAIN(vectorTableFlash)
#pragma DATA_ALIGN(vectorTableFlash, 1024U)
#pragma DATA_SECTION(vectorTableFlash, ".vftable")
void (* const vectorTableFlash[])(void) =
#else
#pragma RETAIN(vectorTableRAM)
#pragma DATA_ALIGN(vectorTableRAM, 1024U)
#pragma DATA_SECTION(vectorTableRAM, ".vtable")
void (* const vectorTableRAM[])(void) =
#endif
{
...
}

Interrupt_setVectorTableOffset((uint32_t) vectorTableRAM)

I am wondering why .vtable appears in the HEX file, as it resides in RAM.
Isn't it useless, since it is not programmed in FLASH?

Further more, how vectorTableRAM is initialized?
For other .text and .const sections I perform an explicit copy form FLASH to RAM.

.TI.ramfunc : {
    aaa.obj(.text)
    bbb.obj(.text)
    bbb.obj(.const)
    ...
} LOAD = CMBANK0_SECTOR0,
  RUN = E0RAM,
  LOAD_START(RamfuncsLoadStart),
  LOAD_SIZE(RamfuncsLoadSize),
  LOAD_END(RamfuncsLoadEnd),
  RUN_START(RamfuncsRunStart),
  RUN_SIZE(RamfuncsRunSize),
  RUN_END(RamfuncsRunEnd),
  ALIGN(16)

memcpy(&RamfuncsRunStart, &RamfuncsLoadStart, (size_t) &RamfuncsLoadSize);

Regards,
Carlo

Even though the vtable section is in the RAM section, the initial values should be stored in flash. This is copied to the RAM by the _c_int00 function.

For example, below is the .map file output for a CM example from C2000ware -

.vtable: load addr=00201690, load size=00000008 bytes, run addr=20000800, run size=00000140 bytes, compression=zero_init

As you can see the vectorTableRAM array allocated in RAM at address 20000800. But the load address (where initial values are stored) is part of Flash memory.

Regards,

Veena

Hello Veena,
looking at my map file I cannot find a .vtable section entry with load form flash / run form ram addresses, as the your one.

The problem seems to be due in having deleted the _FLASH preprocessor symbol form the project.
Restoring this symbol, indeed, the map file contains:
- both .vftable and .vtable sections, and not only .vtable.
- a .vtable entry with load from flash / run from ram addresses, as the your one.

In .vftable section is allocated vectorTableFlash[] and in .vtable is allocated vectorTableRAM[].
I have seen that vectorTableFlash[] is defined in startup_cm.c file, while vectorTableRAM[] is defined in the interrupt.c file of driverlib_cm library.

Which is the relation between vectorTableFlash[] and vectorTableRAM[]?
When is used the first and when the second one?
I need that at runtime, after initialization phase, the bootloader runs entirely in RAM and so that vectorTableRAM[] is used.

Moreover, after having restored the _FLASH preprocessor symbol, should I continue to set vector table address in RAM, with the following instruction, during initialization phase?

Interrupt_setVectorTableOffset((uint32_t) vectorTableRAM)

It seems it is useless, because it is implicity done in the Interrupt_registerHandler() function, that I use to register a couple of ISR:

void
Interrupt_registerHandler(uint32_t interruptNum, void (*intHandler)(void))
{
uint32_t index, value;

...

//
// See if the RAM vector table has been initialized.
//
if(HWREG(NVIC_BASE + NVIC_O_VTOR) != (uint32_t)vectorTableRAM)
{
//
// Copy the vector table from the beginning of FLASH to the RAM vector
// table.
//
value = HWREG(NVIC_BASE + NVIC_O_VTOR);
for(index = 0U; index < NUM_INTERRUPTS; index++)
{
vectorTableRAM[index] = (void (*)(void))HWREG((index * 4U) + value);
}

//
// Point the NVIC at the RAM vector table.
//
HWREG(NVIC_BASE + NVIC_O_VTOR) = (uint32_t)vectorTableRAM;
}

//
// Save the interrupt handler.
//
vectorTableRAM[interruptNum] = intHandler;
}

Regards,
Carlo