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Published 20 hours ago • verified publisher icon foss-for-synopsys-dwc-arc-processors

GNU build sets GP to _f_sdata instead of __SDATA_BEGIN__

Open iguryanov opened this issue 4 years ago • 0 comments
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Issue Summary

  • Type: Bug
  • Category: Library
  • Priority: Low
  • Release Version: 2019.06

Bug

Development Environment

  • HOST OS All OS

  • TOOLCHAIN ARC GNU 2020.03=9.

  • BOARD Customer's board, irrelevant.

  • ARC CORE EM9D.

Bug Description

gcc builds use linker scripts with both _f_sdata and __SDATA_BEGIN__. Normally they are the same in our scripts. Native GNU toolchain startup uses __SDATA_BEGIN__ to configure %GP register. But embARC startup sticks to MWDT agreement and uses _f_sdata.

This works ok until user decides to put __SDATA_BEGIN__ in the middle of the section to extend it's range. (GP-based offset is signed). And linker uses __SDATA_BEGIN__ to calculate relocations and actual offsets.

So when user changes related line in the script to something like this - __SDATA_BEGIN__ = . + 0x100; small data access becomes wrong. Runtime offsets will be 0x100 less (easily driving into negative zone), while startup still sets %GP to the beginning of small data section.

Question

Is it possible to change arc_startup.s in a way that for GCC builds it will choose __SDATA_BEGIN__ for GP?

iguryanov avatar Mar 25 '21 11:03 iguryanov