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ARM Linker Address Map

Senthil Ramakrishnan
Note: This was originally posted on 22nd November 2009 at http://forums.arm.com

Hi All,

Im new to this forum and pretty new to ARM development.
When Im compiling my SW in THumb mode the symbol names
in .map file shows Unaligned memory addresses(Eg: 0x225571).
But the symbol is actually placed in address aligned address(0x225570).
Can anybody explain why linker map shows unaligned address?

Thanks
Parents
  • Arm Employee Badge
    Note: This was originally posted on 22nd November 2009 at http://forums.arm.com

    The least significant bit of the address is used by some ARM/Thumb instructions to determine the instruction set to use, e.g.

    [font="Lucida Console"]MOV r0,#0x21
    BX  r0[/font]

    Branches to address 0x20, and switches to Thumb state, whilst:

    [font="Lucida Console"]MOV r0,#0x20
    BX  r0[/font]

    Branches to address 0x20, and switches to ARM state.

    hth
    s.
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  • Arm Employee Badge
    Note: This was originally posted on 22nd November 2009 at http://forums.arm.com

    The least significant bit of the address is used by some ARM/Thumb instructions to determine the instruction set to use, e.g.

    [font="Lucida Console"]MOV r0,#0x21
    BX  r0[/font]

    Branches to address 0x20, and switches to Thumb state, whilst:

    [font="Lucida Console"]MOV r0,#0x20
    BX  r0[/font]

    Branches to address 0x20, and switches to ARM state.

    hth
    s.
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