Merge pull request #511 from ucb-bar/baremetal-docs

Baremetal docs

docs/Software/Baremetal.rst

@@ -0,0 +1,27 @@
+.. _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>`_.

docs/Software/index.rst

@@ -19,3 +19,4 @@ challenging to modify.
 
    FireMarshal
    Spike
+   Baremetal