This patch introduces the initial support for stdio library in Galileo
platform. For now, only standard output and error are supported. Both
streams use the UART1 device.
Newlib doesn't call open() for stdin, stdout, and stderr which means
that the _write_r call is the first activity the stub will see on
those streams. For that reason, we initialize the UART1 device in
Galileo's platform main() function instead of in open() system call.
This patch implements the _sbrk_r() system call for Galileo platform. This
system call is required by newlib's malloc() implementation. Next patch
will introduce the initial support for stdio library which requires a
working malloc() function for proper operation.
We are not sure about the heap size we should use. Preliminary tests
have shown that stdio library requests 1032 bytes heap. So, as an initial
guess, a 2Kb heap size should be enough for now.
This patch adds the initial support for Intel Galileo Platform. It
contains the minimum set of code required to boot a dummy Contiki
image.
For Galileo initial support, we implemented a linker script, a minimal
bootstrap code, a set of stubbed functions required by newlib, and a
very simple main() function. Moreover, we also define some header files
and macros required by Contiki.
To build applications for this platform you should first build newlib
(in case it wasn't already built). To build newlib you can run the
following command:
$ platform/galileo/bsp/libc/build_newlib.sh
Once newlib is built, you can build applications. To build applications
for Galileo platform you should set TARGET variable to 'galileo'. For
instance, building the hello-world application should look like this:
$ cd examples/hello-world/ && make TARGET=galileo
This will generate the 'hello-world.galileo' file which is a multiboot-
compliant [1] ELF image. This image can be booted by any multiboot-
complaint bootloader such as Grub.
Finally, this patch should be used as a guideline to add the initial
support for others platforms based on x86 SoCs.
[1] https://www.gnu.org/software/grub/manual/multiboot/multiboot.html
