AM263P4: Referring To ORIGIN and LENGTH at Link Time

Hi Kier,

Kier said:

I know how to generate linker symbols for SECTIONS. However, is there a way to generate linker symbols for MEMORY please?

Creating memory symbols in TI ARM CLANG LInker: 10.3. Invoking the Linker — TI Arm Clang Compiler Tools User's Guide

Kier said:

For example, can I refer to the ORIGIN (0x70080000) and LENGTH (0x40000) of OCRAM in my code at link time:

By code do you mean your linker file, then yes you can do it.

Hi Nilabh,

Nilabh Anand said:

By code do you mean your linker file

I mean code as in source code.

For example, this is how to refer to output section .bss.

Linker:

    GROUP  :   {
    .bss : {
    } palign(8)
    RUN_START(__BSS_START)
    RUN_END(__BSS_END)

Source:

extern uint32_t __BSS_START;
extern uint32_t __BSS_END;

int32_t _system_pre_init(void)
{
    uint32_t bss_size = ((uintptr_t)&__BSS_END - (uintptr_t)&__BSS_START);
    (void) memset((void*)&__BSS_START, 0x00, bss_size);
    return 1;
}

That much is already clear.

The question is how to create similar symbols for a MEMORY region?

    OCRAM   : ORIGIN = 0x70040000 , LENGTH = 0x80000 

e.g. The value of OCRAM ORIGIN and OCRAM LENGTH.

If so, what is the syntax please?

In source code:(.c fike)

uint8_t globalBufMem[ICSS_EMAC_PKT_BUF_MEM_SIZE] __attribute__((aligned(128), section(".bss.buf_mem")));

In linker file:

Kier said:

e.g. The value of OCRAM ORIGIN and OCRAM LENGTH.

If so, what is the syntax please?

I have shared an example where you are placing globalBufMem array in the section .bss.buf_mem

Later you can refer the section name and create a memeory region BUF_MEM(make sure this is not overlapping) and using the syntax mentioned below you can place it.

There's a few problems with this.

• The above only helps to determine the start of globalBufMem and length of globalBufMem not the start and length of BUF_MEM. globalBufMem  might not be placed first in BUF_MEM and the value ICSS_EMAC_PKT_BUF_MEM_SIZE may be the same as BUF_MEM LENGTH, but I would need to manually check that at compile time. The point is to determine these values at link time.
• I don't want to use SECTIONS to determine the attributes of a MEMORY entry.

The use case is that I want to check that a write memory access is with in particular range. So my application needs to know the value and BUF_MEM ORIGIN and BUF_MEM LENGTH at link time.

It sounds like the answer is "No, there is no syntax to determine the value of BUF_MEM ORIGIN and BUF_MEM LENGTH at link time in your source code." That's fine, I just need to know that that is the answer.

Hi Kier,

https://software-dl.ti.com/codegen/docs/tiarmclang/compiler_tools_user_guide/compiler_manual/linker_description/05_linker_command_files/assigning-symbols-at-link-time-stdz0758478.html?highlight=start#assigning-exact-start-end-and-size-values-of-a-section-to-a-symbol

Let me know if this is helpful to you.

Thanks Nilabh but no.

The closest is the LAST operator but that only gives the last occupied address the memory range. I would be looking for an START and END operators for the memory ranges but they are only applicable to the memory sections.