DDR linker script for Cortex-M4 on i.MX 8QuadMax using TCM for quick data/code access

Cryptic — Wed, 26 Apr 2023 08:18:25 GMT

The following snippet is taken from the MIMX8QM6xxxFF_cm4_core0_ddr_ram.ld template linker script in the SDK:

__TDATA_ROM = __DATA_ROM + SIZEOF(.data); /* Symbol is used by startup for TCM data initialization */ .quickaccess : AT(__TDATA_ROM) { __quickaccess_start__ = .; . = ALIGN(32); *(CodeQuickAccess) . += SAFE_BOUNDARY_LEN; *(DataQuickAccess) . = ALIGN(128); __quickaccess_end__ = .; } > m_tcml

Few questions:

Why are the CodeQuickAccess 32-byte, and DataQuickAccess 128-byte aligned? Why can't we live with 4-byte alignment?
Is it possible to break the .quickaccess section into two parts, such that we entirely dedicate m_tcml to CodeQuickAccess and m_tcmu to DataQuickAccess?

Here's the memory specification overview:

MEMORY { m_interrupts (RX) : ORIGIN = 0x88800000, LENGTH = 0x00000A00 m_text (RX) : ORIGIN = 0x88800A00, LENGTH = 0x003FF600 m_data (RW) : ORIGIN = 0x88C00000, LENGTH = 0x00400000 m_data2 (RW) : ORIGIN = 0x89000000, LENGTH = 0x07000000 m_tcml (RW) : ORIGIN = 0x1FFE0020, LENGTH = 0x0001FFE0 m_tcmu (RW) : ORIGIN = 0x20000000, LENGTH = 0x00020000 }

Thanks!

Re: DDR linker script for Cortex-M4 on i.MX 8QuadMax using TCM for quick data/code access

Dhruvit — Tue, 02 May 2023 11:49:56 GMT

Hi @Cryptic,

I hope you are doing well

Why are the CodeQuickAccess 32-byte, and DataQuickAccess 128-byte aligned? Why can't we live with a 4-byte alignment?

=> Yes, We can use 4 byte alignment.

Is it possible to break the .quickaccess section into two parts, such that we entirely dedicate m_tcml to CodeQuickAccess and m_tcmu to DataQuickAccess?

=> Yes, It is possible to do the same. But it is not recommended to change the linker script other than the default.

Thanks & Regards,

Dhruvit Vasavada

topic Re: DDR linker script for Cortex-M4 on i.MX 8QuadMax using TCM for quick data/code access in i.MX Processors

DDR linker script for Cortex-M4 on i.MX 8QuadMax using TCM for quick data/code access

Re: DDR linker script for Cortex-M4 on i.MX 8QuadMax using TCM for quick data/code access