Specifications

add_memory_region onchip_ram $slave_desc $offset $new_span

add_memory_region onchip_special $slave_desc $split_offset $split_span

If you pass this Tcl script to nios2-bsp, it runs after the default Tcl script runs and sets up a linker region

named onchip_ram0. You pass the Tcl script to nios2-bsp as follows:

nios2-bsp hal my_bsp --script reserve_1024_onchip_ram.tclr

Note: Take care that one of the new memory regions has the same name as the original memory region.

If you run nios2-bsp again to update your BSP without providing the --script option, your BSP reverts

to the default linker memory regions and your onchip_special memory region disappears. To preserve

it, you can either provide the --script option to your Tcl script or pass the DONT_CHANGE keyword to the

default Tcl script as follows:

nios2-bsp hal my_bsp --default_memory_regions DONT_CHANGEr

Altera recommends that you use the --script approach when updating your BSP. This approach allows

the default Tcl script to update memory regions if memories are added, removed, renamed, or resized.

Using the DONT_CHANGE keyword approach does not handle any of these cases because the default Tcl

script does not update the memory regions at all.

For more information about using the --script argument, refer to the “Calling a Custom BSP Tcl Script”

chapter.

Related Information

• Calling a Custom BSP Tcl Script on page 4-26

• Nios II Software Build Tools Reference on page 15-1

For an explanation of each Tcl command used in this example, refer to the "Nios II Software Build

Tools Reference" chapter.

Creating a Custom Linker Section

The Nios II SBT provides a Tcl command, add_section_mapping, to create a linker section.

The default Tcl script creates these default sections for you using the add_section_mapping Tcl

command:

• .entry

• .exceptions

• .text

• .rodata

• .rwdata

• .bss

• .heap

• .stack

Creating a Linker Section for an Existing Region

To create your own section named special_section that is mapped to the linker region named

onchip_special, use the following command to run nios2-bsp:

nios2-bsp hal my_bsp --cmd add_section_mapping special_section onchip_specialr

When the nios2-bsp-generate-files utility (called by nios2-bsp) generates the linker script linker.x, the

linker script has a new section mapping. The order of section mappings in the linker script is determined

4-12

Creating a Custom Linker Section

NII5V2

2015.05.14

Altera Corporation

Nios II Software Build Tools

Send Feedback