NuttX 0.2.8

NuttX project is a real-time embedded operating system (RTOS). It has a small footprint that is usable in micro-controller environments. It is fully scalable from tiny (8-bit) to moderate embedded (32-bit) systems. It also aims to be fully compliant to standards, to be fully real time, and to be totally open.
Main features:
Small Footprint
- Usable in all but the tightest micro-controller environments, The focus is on the tiny-to-small, deeply embedded environment.
Rich Feature OS Set
- The goal is to provide most standard POSIX OS interfaces to support a rich multi-threaded development environment.
- NON-GOALS: (1) It is not a goal to provide OS subsystems such as network or USB (but these could obviously be added). (2) There is no MMU-based support for processes. At present, NuttX assumes a flat address space.
Highly Scalable
- Fully scalable from tiny (8-bit) to moderate embedded (32-bit). Scalability with rich feature set is accomplished with: Many tiny source files, link from static libraries, highly configurable, use of weak symbols when available.
Standards Compliance
- NuttX strives to achieve a high degree of standards compliance. The primary governing standards are POSIX and ANSI standards. Additional standard APIs from Unix and other common RTOSs are adopted for functionality not available under these standards or for functionaly that is not appropriate for the deeply-embedded RTOS (such as fork()).
- Because of this standards conformance, software developed under other standard OSs (such as Linux) should port easily to NuttX.
Real-Time
- Fully pre-emptible, fixed priority and round-robin scheduling.
Totally Open
- Non-restrictive BSD license.
Enhancements:
- tools/Makefile.mkconfig: Under Cygwin, executable has a different name
- tools/mkdeps.sh & arch/arm/src/Makefile: Corrected a problem makeing dependencies
- tools/zipme.sh: Force directory name to be nuttx-xx.yy.zz
- fs/fs_opendir.c: Correct errors in semaphore usage that can cause deadlock.
- lib/lib_getopt.c: Added getopt() support
- examples/nsh/: NSH now supports cat, mount, umount, and mkdir. ls supports -l -s, and -R
- Added basic OS support to manage environment variables: environment storage, cloning on task creation, sharing on pthread creation, destruction on thread/task exit.
- Add environment variables APIs: environ, getenv, putenv, clearenv, setenv, unsetenv
- Correct an error in realloc() when the block is extended "down" in memory. In this case, the old memory contents need to be copied to the new location and an allocated bit was not being set.
- examples/ostest/: Added an environment variable test.
- examples/nsh/: Break into several files.
- lib/: Added strrchr, basename, dirname
- examples/nsh/: Add cp, rm, rmdir, set, unset commands. echo will now print environment variables.