ldscript-generator

This is a python tool based on pydevicetree (GitHub/PyPI) which generates linker scripts for Freedom Metal applications.

Usage

usage: generate_ldscript.py [-h] -d DTS -o OUTPUT [--scratchpad | --ramrodata]

Generate linker scripts from Devicetrees

optional arguments:
  -h, --help            show this help message and exit
  -d DTS, --dts DTS     The path to the Devicetree for the target
  -o OUTPUT, --output OUTPUT
                        The path of the linker script file to output
  --scratchpad          Emits a linker script with the scratchpad layout
  --ramrodata           Emits a linker script with the ramrodata layout
  --freertos            Emits a linker script with specific layout for freertos

Required Devicetree Properties

This linker script generator expects that the Devicetree has annotated the desired memory map for the resulting linker script through properties in the /chosen node. Those properties are:

metal,entry, which describes which memory region read-only data should be placed in
metal,itim, which describes which memory region should be treated as instruction tightly-integrated memory for low-latency instruction fetch
metal,ram, which describes which memory region should be treated as ram

Each of these properties is a prop-encoded-array with the following triplet of values:

A reference to a node which describes memory with the reg property
An integer describing which 0-indexed tuple in the reg property should be used
An integer describing the offset into the memory region described by the requested reg tuple

For example, the chosen node may include the following properties:

chosen {
    metal,entry = <&testram0 0 0>;
    metal,itim = <&L11 0 0>;
    metal,ram = <&L28 0 0>;
};

Example Invocation

$ ./generate_ldscript.py -d e31.dts -o metal.default.lds
Generating linker script with default layout
Selected memories in design:
        RAM:  0x80000000-0x8000ffff (/soc/dtim@80000000)
        ITIM: 0x01800000-0x01801fff (/soc/itim@1800000)
        ROM:  0x20000000-0x3ffffffe (/soc/ahb-periph-port@20000000/testram@20000000)

$ head -n 20 metal.default.lds
/* Copyright (c) 2020 SiFive Inc. */
/* SPDX-License-Identifier: Apache-2.0 */
OUTPUT_ARCH("riscv")


/* Default Linker Script
 *
 * This is the default linker script for all Freedom Metal applications.
 */


ENTRY(_enter)

MEMORY
{
    ram (rwai!x) : ORIGIN = 0x80000000, LENGTH = 0x10000
    itim (rwxai) : ORIGIN = 0x1800000, LENGTH = 0x2000
    rom (rxai!w) : ORIGIN = 0x20000000, LENGTH = 0x1fffffff
    
}

Copyright and License

The contents of this repository are distributed according to the terms described in the LICENSE file.

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