NSPR platforms¶

Build System and Supported Platforms¶

NSPR has been implemented on over 20 platforms. A platform may have more than one implementation strategy of its multi threading and I/O facilities. This article explains the NSPR build system and how to specify a particular implementation strategy, compiler or compiler switches, or the target OS for your build on each platform.

Implementation Strategies¶

Threads are at the core of NSPR, and the I/O functions are tied to the multi threading facilities because many I/O functions may block the calling threads. NSPR has multiple implementation strategies of its multi threading and I/O functions. The various implementation strategies can be organized into the hierarchy below:

Classic NSPR (This is our first code base, hence the term “classic NSPR”):

Local threads only: All threads are user-level threads implemented by NSPR. Global threads only: All threads are native threads supplied by the OS vendor. For example, Solaris UI (Unix International) threads and Win32 threads. Combined: NSPR multiplexes user-level threads on top of native, kernel-level threads. This is also called the MxN model. At present, there are three implementations of the combined model.

IRIX: sprocs + NSPR user-level threads
Windows NT: Win32 threads + NT fibers
Pthreads-user: kernel-level pthreads + NSPR user-level threads

Pthreads: All threads are pthreads. The relevant code is in mozilla/nsprpub/pr/src/pthreads (threads and I/O). Classic NSPR and pthreads have relatively disjoint code bases in the threads and I/O areas:

Classic NSPR: mozilla/nsprpub/pr/src/threads/combined (threads), mozilla/nsprpub/pr/src/io (I/O)
Pthreads: mozilla/nsprpub/pr/src/pthreads (threads and I/O)

Note that some files under mozilla/nsprpub/pr/src/io are shared by both classic NSPR and pthreads. Consult mozilla/nsprpub/pr/src/Makefile for the definitive list of files used by each implementation strategy (see the definition of the makefile variable OBJS).

Compilers¶

For ease of integration with third-party libraries, which may use native threads, NSPR uses the native threads whenever possible. As a result, native compilers are used to build NSPR on most platforms because they have better debugging support for native threads. The only exception is Solaris, where both cc and gcc are used.

NSPR Build System¶

NSPR build system is based on GNU make. We use GNU make 3.74 on Unix, but our makefiles should work fine under newer versions of GNU make.

Every directory in NSPR has a makefile named Makefile, which includes the makefile fragments in mozilla/nsprpub/config. NSPR makefiles implement the common Makefile targets such as export, libs, and install. However, some makefiles targets are no-op in NSPR because they are not necessary for NSPR.

To build NSPR, change directory to the root of our source tree cd mozilla/nsprpub and then issue the command gmake Make will recursively go into all the subdirectories and the right things will happen.

The table below lists the common NSPR makefile targets.

`all`	The default target. Same as `export` `libs` `install`.
`export`	Do a complete build.
`libs`	No-op.
`install`	No-op.
`depend`	No-op. This means that NSPR makefiles do not have header file dependencies.
`clean`	Remove `.o` files.
`clobber`	Remove `.o` files, libraries, and executable programs.
`realclean`	Remove all generated files and directories.
`clobber_all`	Same as `realclean`.

The table below lists common makefile variables that one can specify on the command line to customize a build..

`BUILD_OPT`	Optimized build (default: debug build).
`OS_TARGET`	Set to the target OS (`WIN95` or `WIN16`) when doing cross-compilation on NT (default: same as the host OS).
`NS_USE_GCC`	Use gcc and g++ (default: native compilers).
`USE_PTHREADS`	Build pthreads version.
`CLASSIC_NSPR`	Build classic NSPR version (usually local threads only).
`PTHREADS_USER`	Build pthreads-user version.
`LOCAL_THREADS_ONLY`	Build local threads only version.
`USE_DEBUG_RTL`	On Win32, compile with `/MDd` in the debug build (default: `/MD`). Optimized build always uses `/MD`.
`USE_N32`	On IRIX, compile with `-n32` (default: `-32`).
`USE_IPV6`	Enable IPv6.
`MOZILLA_CLIENT`	Adjust NSPR build system for Netscape Client (mozilla).