printf() linker error – "undefined reference to `_sbrk'"

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This topic contains 2 replies, has 2 voices, and was last updated by  support 1 week, 2 days ago.

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  • #10023

    bmcdonnell_psi
    Participant

    I have an STM32F072RB project using the toolchain ARM in C:\SysGCC\arm-eabi.

    When I try to build my project and it includes an integer to string conversion using any function in the printf() family (sprintf(), vsnprintf(), etc.), I get the following linker error.

    Severity Code Description Project File Line Suppression State
    Error undefined reference to `_sbrk’ MyProject¬†q:\gnu\newlib-nano\newlib-nano-2016q3\newlib\libc\reent\sbrkr.c 58
    Error ld returned 1 exit status MyProject C:\[path to MyProject]\collect2.exe 1

    Why is this happening, and how can I fix it?

     

    I have the latest VisualGDB packages, as shown below.

    • This topic was modified 1 week, 2 days ago by  bmcdonnell_psi. Reason: add version details
    #10025

    bmcdonnell_psi
    Participant

    Actually, it’s not just for number conversions. Maybe for every time there’s a format string followed by one or more var args? I’m not totally sure the circumstances.

    #10031

    support
    Keymaster

    Hi,

    This error happens because the newlib-nano does not include the default implementations for system calls like _sbrk().

    To fix this, please simply enable the ‘provide default implementations for system calls’ checkbox on the first page of VisualGDB Project Properties.

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