RTEMS 4.5.1-pre3 On-Line Library

Cygwin 1.0 or Newer

Getting Started with RTEMS for C/C++ Users

7.1: Cygwin 1.0 or Newer

Recent versions of Cygwin are vastly improved over the beta versions. Most of the oddities, instabilities, and performance problems have been resolved. The installation procedure is much simpler. However, there are a handful of issues that remain to successfully use Cygwin as an RTEMS development environment.

There is no cc program by default. The GNU configure scripts used by RTEMS require this to be present to work properly. The solution is to link gcc.exe to cc.exe.
Make sure you unarchive and build in a binary mounted filesystem (e.g. mounted with the -b option). Otherwise, many confusing errors will result.
If you want to use RPM, you will have to obtain that separately by following the links from the main Cygwin site.
When using the RPMs, there may be warnings about /etc/mtab while installing the info files. This can be ignored.
A user has reported that they needed to set CYGWIN=ntsec for chmod to work correctly, but had to set CYGWIN=nontsec for compile to work properly (otherwise there were complaints about permissions on a temporary file).
If you want to build the tools from source, you have the same options as UNIX users -- bit or RPM.

Getting Started with RTEMS for C/C++ Users