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chipyard/docs/Software/Baremetal.rst
2020-04-15 14:21:12 -07:00

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.. _baremetal-programs:
Baremetal RISC-V Programs
==========================
To build baremetal RISC-V programs to run in simulation, we use the riscv64-unknown-elf cross-compiler and a fork of the libgloss board support package. To build such a program yourself, simply invoke the cross-compiler with the flags "-fno-common -fno-builtin-printf -specs=htif_nano.specs" and the link with the arguments "-static -specs=htif_nano.specs". For instance, if we want to run a "Hello, World" program in baremetal, we could do the following.
.. code:: c
#include <stdio.h>
int main(void)
{
printf("Hello, World!\n");
return 0;
}
.. code:: bash
$ riscv64-unknown-elf-gcc -fno-common -fno-builtin-printf -specs=htif_nano.specs -c hello.c
$ riscv64-unknown-elf-gcc -static -specs=htif_nano.specs hello.o -o hello.riscv
$ spike hello.riscv
Hello, World!
For more examples, look at the `tests/ directory <https://github.com/ucb-bar/chipyard/tree/master/tests>`_ in the chipyard repository.
For more information about the libgloss port, take a look at `its README <https://github.com/ucb-bar/libgloss-htif/blob/master/README.md>`_.