Makefile modification to allow building optiboot in more environments.

Allows building within the Arduino Source tree, and within the Arduino
IDE tree, as well as using CrossPack on Mac.

Adds README.TXT to track arduino-specific changes (and documents the
new build options.)

This addresses Arduino issue:

  http://code.google.com/p/arduino/issues/detail?id=487

And optiboot issue

  http://code.google.com/p/optiboot/issues/detail?id=1

(which can be thought of as a subset of the Arduno issue.)

Note that the binaries produced after these Makefile changes (using any
of the compile environments) are identical to those produced by the
crosspack-20100115 environment on a Mac.

1 files changed, 55 insertions, 0 deletions

diff --git a/bootloaders/optiboot/README.TXT b/bootloaders/optiboot/README.TXT
new file mode 100644
index 0000000..9a68e23
--- /dev/null
+++ b/bootloaders/optiboot/README.TXT
@@ -0,0 +1,55 @@
+This directory contains the Optiboot small bootloader for AVR
+microcontrollers, somewhat modified specifically for the Arduino
+environment.
+
+Optiboot is more fully described here: http://code.google.com/p/optiboot/
+and is the work of Peter Knight (aka Cathedrow), building on work of Jason P
+Kyle, Spiff, and Ladyada.  Arduino-specific modification are by Bill
+Westfield (aka WestfW)
+
+Arduino-specific issues are tracked as part of the Arduino project
+at http://code.google.com/p/arduino
+
+
+------------------------------------------------------------
+Building optiboot for Arduino.
+
+Production builds of optiboot for Arduino are done on a Mac in "unix mode"
+using CrossPack-AVR-20100115.  CrossPack tracks WINAVR (for windows), which
+is just a package of avr-gcc and related utilities, so similar builds should
+work on Windows or Linux systems.
+
+One of the Arduino-specific changes is modifications to the makefile to
+allow building optiboot using only the tools installed as part of the
+Arduino environment, or the Arduino source development tree.  All three
+build procedures should yield identical binaries (.hex files) (although
+this may change if compiler versions drift apart between CrossPack and
+the Arduino IDE.)
+
+
+Building optiboot in the arduino IDE install.
+
+Work in the .../hardware/arduino/bootloaders/optiboot/ and use the
+"omake <targets>" command, which just generates a command that uses
+the arduino-included "make" utility with a command like:
+    make OS=windows ENV=arduino <targets>
+or  make OS=macosx ENV=arduino <targets>
+On windows, this assumes you're using the windows command shell.  If
+you're using a cygwin or mingw shell, or have one of those in your
+path, the build will probably break due to slash vs backslash issues.
+On a Mac, if you have the developer tools installed, you can use the
+Apple-supplied version of make.
+The makefile uses relative paths ("../../../tools/" and such) to find
+the programs it needs, so you need to work in the existing optiboot
+directory (or something created at the same "level") for it to work.
+
+
+Building optiboot in the arduino source development install.
+
+In this case, there is no special shell script, and you're assumed to
+have "make" installed somewhere in your path.
+Build the Arduino source ("ant build") to unpack the tools into the
+expected directory.
+Work in Arduino/hardware/arduino/bootloaders/optiboot and use
+    make OS=windows ENV=arduinodev <targets>
+or  make OS=macosx ENV=arduinodev <targets>