Getting Started with Picolibc

Overview

Experimental support of Picolibc for ARC Classic targets is introduced in arc-2026.03 release of GNU toolchains for ARC processors.

Below you can find a series of examples of using it for building and running applications for ARC Classic targets.

Check Choosing nSIM Templates for information about choosing correct target options.

Building and Running for nSIM

Consider this simple example with hello.c filename:

#include <stdio.h>

int main()
{
    printf("Hello, World!\n");
    return 0;
}

Build the application with GNU nSIM interface for input/output and run it:

$ arc-snps-elf-gcc \
    -mcpu=archs \
    -specs=picolibc.specs \
    --crt0=semihost \
    --oslib=semihost \
    hello.c -o hello.elf

$ nsimdrv -tcf $NSIM_HOME/etc/tcf/templates/hs38_full.tcf -on nsim_emt hello.elf
Hello, World!

Build the application with Hostlink nSIM interface for input/output and run it:

$ arc-snps-elf-gcc \
    -mcpu=archs \
    -specs=picolibc.specs \
    --crt0=hl \
    --oslib=hl \
    hello.c -o hello.elf

$ nsimdrv -tcf $NSIM_HOME/etc/tcf/templates/hs38_full.tcf hello.elf
Hello, World!

Build with a size-optimized version of Picolibc:

$ arc-snps-elf-gcc \
    -mcpu=archs \
    -specs=picolibc.specs \
    --crt0=semihost \
    --oslib=semihost \
    -specs=nano.specs \
    hello.c -o hello.elf

Build with custom memory layout, heap size and stack size:

$ arc-snps-elf-gcc \
    -mcpu=archs \
    -specs=picolibc.specs \
    --crt0=semihost \
    --oslib=semihost \
    -Wl,-defsym=__f4lash=0x0 \
    -Wl,-defsym=__flash_size=16M \
    -Wl,-defsym=__ram=0x80000000 \
    -Wl,-defsym=__ram_size=16M \
    -Wl,-defsym=__heap_size_min=32M \
    -Wl,-defsym=__stack_size=32M \
    hello.c -o hello.elf

Compiling C++ Applications

Consider a simple code example with hello.cpp filename:

#include <iostream>

int main()
{
        std::cout << "Hello, World!" << std::endl;
        return 0;
}

For compiling C++ applications use -specs=picolibcpp.specs:

$ arc-snps-elf-g++ \
    -mcpu=archs \
    -specs=picolibcpp.specs \
    --crt0=semihost \
    --oslib=semihost \
    -Wl,--defsym=__flash_size=4M \
    -Wl,--defsym=__ram_size=4M \
    hello.cpp -o hello.elf

$ nsimdrv -tcf $NSIM_HOME/etc/tcf/templates/hs38_full.tcf -on nsim_emt hello.elf
Hello, World!

Building and Running for Boards

Build for ARC HS Development Kit:

$ arc-snps-elf-gcc \
    -mcpu=hs38_linux \
    -specs=picolibc.specs \
    -specs=hsdk.specs \
    --crt0=hosted \
    --oslib=hsdk \
    hello.c -o hello.elf

Build for ARC EM Software Development Platform 1.0 and 1.1:

$ arc-snps-elf-gcc \
    -mcpu=em4_fpuda \
    -mmpy-option=6 \
    -mfpu=fpuda_all \
    -specs=picolibc.specs \
    -specs=emsdp1.1.specs \
    --crt0=hosted \
    --oslib=emsdp \
    hello.c -o hello.elf

Build for ARC EM Software Development Platform 1.2:

$ arc-snps-elf-gcc \
    -mcpu=em4_fpuda \
    -mmpy-option=6 \
    -mfpu=fpuda_all \
    -specs=picolibc.specs \
    -specs=emsdp1.2.specs \
    --crt0=hosted \
    --oslib=emsdp \
    hello.c -o hello.elf