Understanding Section Merging Problems
Section merging problems in the IAR Linker often arise due to conflicts or overlaps in memory allocation, incorrect placement directives, or incompatible section attributes. Understanding how these problems manifest is key to resolving them effectively. When different sections with similar names or addresses overlap, the linker may generate warnings or errors.
Common Causes of Section Merging Problems
- Overlapping Memory Regions: Multiple segments trying to access the same memory region.
- Incorrect Linker Configuration: Misconfiguration in the linker command file, such as incorrect section placement.
- Incompatible Attributes: Sections having conflicting attributes that prevent them from being merged properly.
Steps to Resolve Section Merging Issues
Review Linker Configuration
Ensure that the linker configuration is correctly set up to accommodate your project’s memory model. Review the .icf (IAR configuration file) settings and check that the memory regions are defined accurately.
define region ROM_region = mem:[from 0x00000000 to 0x00007FFF];
define block program_start with fixed order
{
ro start_code { section .text };
rw initialized_data { section .data};
zi uninitialized_data { section .bss};
};
Analyze Linker Warnings and Errors
The linker will often provide warnings or errors that point towards the sections or segments that are causing the issue. Carefully read the linker messages to understand the source of the problem. Enable verbose output for more detailed logs.
Modify Section Attributes
If the issue arises from incompatible section attributes, review the section modifiers. Align the attributes where necessary, ensuring that they do not conflict. For example, confirm if sections are set as READ, WRITE, etc., appropriately.
#pragma location=".my_custom_section"
__root const int myData[5] = {1, 2, 3, 4, 5};
Utilize Custom Linker Commands
Customizing the linker script can give more direct control over segment placement. Define specific locations for problematic sections to avoid automatic merging.
define region MY_REGION = mem:[from 0x20000000 to 0x20007FFF];
place at address mem:0x20000000 { section .my_custom_section };
Isolate Problematic Sections
When a section consistently causes issues, isolate it by giving it a unique memory region. This can prevent conflicts and overlaps with other sections.
Reorganize Code
Consider reorganizing or refactoring your code to reduce the number of sections and simplify memory layout. Group similar functions or data in the same source file if possible, to encourage simpler section handling.
Debugging Aid: Map Files
Generate a map file to inspect how the linker allocates memory. Map files provide detailed information about section sizes, starting locations, and assignments, which can be invaluable for diagnosing section merging problems.
To enable map file output, ensure your project settings reflect the option:
--map myProject.map
Consult IAR Documentation and Support
If troubleshooting steps don’t resolve the issue, consult IAR’s extensive documentation or contact technical support. They offer detailed guides and examples that might cover the specific merging issues encountered.
