embedded build_error ai_generated true

arm-none-eabi-ld: section .data VMA 0x20000000 overlaps section .bss VMA 0x20000000 in region RAM

ID: embedded/arm-gcc-section-overlap-in-ram

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95%Fix Rate
90%Confidence
1Evidence
2023-11-08First Seen

Version Compatibility

VersionStatusIntroducedDeprecatedNotes
ARM GCC 12.3.1 active — — —
GNU ld 2.40 active — — —
STM32CubeIDE 1.14.0 active — — —

Root Cause

Linker script defines .data and .bss sections with overlapping virtual memory addresses in RAM region, typically due to incorrect LMA/VMA alignment or missing section padding.

generic

中文

链接脚本在 RAM 区域中为 .data 和 .bss 段定义了重叠的虚拟内存地址，通常是由于 LMA/VMA 对齐错误或缺少段填充。

Official Documentation

https://gcc.gnu.org/onlinedocs/gcc-12.3.0/gnu_lnk.html

Workarounds

  1. 95% success Edit linker script (.ld file) to add explicit alignment and gap between .data and .bss sections: . = ALIGN(4); .data : { *(.data) } >RAM AT>FLASH; . = ALIGN(4); .bss : { *(.bss) } >RAM; Ensure .bss VMA starts after .data end address, e.g., .bss VMA = .data VMA + SIZEOF(.data) + 4. 
    Edit linker script (.ld file) to add explicit alignment and gap between .data and .bss sections: . = ALIGN(4); .data : { *(.data) } >RAM AT>FLASH; . = ALIGN(4); .bss : { *(.bss) } >RAM; Ensure .bss VMA starts after .data end address, e.g., .bss VMA = .data VMA + SIZEOF(.data) + 4.
  2. 90% success Use the linker script's built-in PROVIDE and ASSERT to detect overlap at build time: add ASSERT(SIZEOF(.data) + SIZEOF(.bss) <= LENGTH(RAM), "RAM overflow"); in the script. 
    Use the linker script's built-in PROVIDE and ASSERT to detect overlap at build time: add ASSERT(SIZEOF(.data) + SIZEOF(.bss) <= LENGTH(RAM), "RAM overflow"); in the script.

中文步骤

  1. Edit linker script (.ld file) to add explicit alignment and gap between .data and .bss sections: . = ALIGN(4); .data : { *(.data) } >RAM AT>FLASH; . = ALIGN(4); .bss : { *(.bss) } >RAM; Ensure .bss VMA starts after .data end address, e.g., .bss VMA = .data VMA + SIZEOF(.data) + 4.
  2. Use the linker script's built-in PROVIDE and ASSERT to detect overlap at build time: add ASSERT(SIZEOF(.data) + SIZEOF(.bss) <= LENGTH(RAM), "RAM overflow"); in the script.

Dead Ends

Common approaches that don't work:

  1. Increase RAM size in linker script (e.g., change RAM length from 64K to 128K) 90% fail

    Overlap is due to address assignment, not insufficient total RAM; increasing size does not separate overlapping addresses.

  2. Move all variables to .data section by removing __attribute__((section(".bss"))) 80% fail

    This may shift the problem but not resolve the underlying VMA collision; .data and .bss still share same base address.