Embedded Design Handbook

ID 683689
Date 8/28/2023
Public
Document Table of Contents

5.2.1.1. Nios® II Processor Application Execute-In-Place from Boot Flash

The boot flash5 controller is designed so that the boot flash address space is immediately accessible to the Nios® II processor upon system reset, without the need to initialize the memory controller or memory devices. This enables Nios® II to execute application code, stored on the boot devices, directly without the use of a boot copier to copy the code to another memory type.

When a boot copier is not used, the Nios® II application .text linker sections are set to the boot flash memory region while .bss, .rodata, .rwdata, .stack and .heap linker sections are set to the RAM memory region. Enable the alt_load () function in the BSP Settings to copy the data sections (.rodata, .rwdata, .exceptions) to the RAM upon system reset. The code section (.text) remains in the boot flash memory region. 6

5 Boot Flash refers to UFM, EPCQ, QSPI, or CFI flash devices.
6 .text, .rodata, .rwdata, and .exceptions are part of the Nios® II default section names. For more details about these functions, refer to Nios® II Gen2 Software Developer’s Handbook.