+@node System properties
+@chapter System properties
+
+The runtime behavior of the @code{libgcj} library can be modified by setting
+certain system properties. These properties can be compiled into the program
+using the @code{-D@var{name}[=@var{value}]} option to @command{gcj} or by
+setting them explicitly in the program by calling the
+@code{java.lang.System.setProperty()} method. Some system properties are only
+used for informational purposes (like giving a version number or a user name).
+A program can inspect the current value of a property by calling the
+@code{java.lang.System.getProperty()} method.
+
+@menu
+* Standard Properties:: Standard properties supported by @code{libgcj}
+* GNU Classpath Properties:: Properties found in Classpath based libraries
+* libgcj Runtime Properties:: Properties specific to @code{libgcj}
+@end menu
+
+@node Standard Properties
+@section Standard Properties
+
+The following properties are normally found in all implementations of the core
+libraries for the Java language.
+
+@table @gcctabopt
+
+@item java.version
+The @code{libgcj} version number.
+
+@item java.vendor
+Set to @samp{The Free Software Foundation, Inc.}
+
+@item java.vendor.url
+Set to @uref{http://gcc.gnu.org/java/}.
+
+@item java.home
+The directory where @code{gcj} was installed. Taken from the @code{--prefix}
+option given to @command{configure}.
+
+@item java.class.version
+The class format version number supported by the libgcj byte code interpreter.
+(Currently @samp{46.0})
+
+@item java.vm.specification.version
+The Virtual Machine Specification version implemented by @code{libgcj}.
+(Currently @samp{1.0})
+
+@item java.vm.specification.vendor
+The name of the Virtual Machine specification designer.
+
+@item java.vm.specification.name
+The name of the Virtual Machine specification
+(Set to @samp{Java Virtual Machine Specification}).
+
+@item java.vm.version
+The @command{gcj} version number.
+
+@item java.vm.vendor
+Set to @samp{The Free Software Foundation, Inc.}
+
+@item java.vm.name
+Set to @samp{GNU libgcj}.
+
+@item java.specification.version
+The Runtime Environment specification version implemented by @code{libgcj}.
+(Currently set to @samp{1.3})
+
+@item java.specification.vendor
+The Runtime Environment specification designer.
+
+@item java.specification.name
+The name of the Runtime Environment specification
+(Set to @samp{Java Platform API Specification}).
+
+@item java.class.path
+The paths (jar files, zip files and directories) used for finding class files.
+
+@item java.library.path
+Directory path used for finding native libraries.
+
+@item java.io.tmpdir
+The directory used to put temporary files in.
+
+@item java.compiler
+Name of the Just In Time compiler to use by the byte code interpreter.
+Currently not used in @code{libgcj}.
+
+@item java.ext.dirs
+Directories containing jar files with extra libraries. Will be used when
+resolving classes.
+
+@item java.protocol.handler.pkgs
+A @samp{|} separated list of package names that is used to find classes that
+implement handlers for @code{java.net.URL}.
+
+@item java.rmi.server.codebase
+A list of URLs that is used by the @code{java.rmi.server.RMIClassLoader}
+to load classes from.
+
+@item jdbc.drivers
+A list of class names that will be loaded by the @code{java.sql.DriverManager}
+when it starts up.
+
+@item file.separator
+The separator used in when directories are included in a filename
+(normally @samp{/} or @samp{\} ).
+
+@item file.encoding
+The default character encoding used when converting platform native files to
+Unicode (usually set to @samp{8859_1}).
+
+@item path.separator
+The standard separator used when a string contains multiple paths
+(normally @samp{:} or @samp{;}), the string is usually not a valid character
+to use in normal directory names.)
+
+@item line.separator
+The default line separator used on the platform (normally @samp{\n}, @samp{\r}
+or a combination of those two characters).
+
+@item policy.provider
+The class name used for the default policy provider returned by
+@code{java.security.Policy.getPolicy}.
+
+@item user.name
+The name of the user running the program. Can be the full name, the login name
+or empty if unknown.
+
+@item user.home
+The default directory to put user specific files in.
+
+@item user.dir
+The current working directory from which the program was started.
+
+@item user.language
+The default language as used by the @code{java.util.Locale} class.
+
+@item user.region
+The default region as used by the @code{java.util.Local} class.
+
+@item user.variant
+The default variant of the language and region local used.
+
+@item user.timezone
+The default timezone as used by the @code{java.util.TimeZone} class.
+
+@item os.name
+The operating system/kernel name that the program runs on.
+
+@item os.arch
+The hardware that we are running on.
+
+@item os.version
+The version number of the operating system/kernel.
+
+@item awt.appletWarning
+The string to display when an untrusted applet is displayed.
+Returned by @code{java.awt.Window.getWarningString()} when the window is
+``insecure''.
+
+@item awt.toolkit
+The class name used for initializing the default @code{java.awt.Toolkit}.
+Defaults to @code{gnu.awt.gtk.GtkToolkit}.
+
+@item http.proxyHost
+Name of proxy host for http connections.
+
+@item http.proxyPort
+Port number to use when a proxy host is in use.
+
+@end table
+
+@node GNU Classpath Properties
+@section GNU Classpath Properties
+
+@code{libgcj} is based on the GNU Classpath (Essential Libraries for Java) a
+GNU project to create free core class libraries for use with virtual machines
+and compilers for the Java language. The following properties are common to
+libraries based on GNU Classpath.
+
+@table @gcctabopt
+
+@item gcj.dumpobject
+Enables printing serialization debugging by the @code{java.io.ObjectInput} and
+@code{java.io.ObjectOutput} classes when set to something else then the empty
+string. Only used when running a debug build of the library.
+
+@item gnu.classpath.vm.shortname
+This is a succinct name of the virtual machine. For @code{libgcj},
+this will always be @samp{libgcj}.
+
+@item gnu.classpath.home.url
+A base URL used for finding system property files (e.g.,
+@file{classpath.security}). By default this is a @samp{file:} URL
+pointing to the @file{lib} directory under @samp{java.home}.
+
+@end table
+
+@node libgcj Runtime Properties
+@section libgcj Runtime Properties
+
+The following properties are specific to the @code{libgcj} runtime and will
+normally not be found in other core libraries for the java language.
+
+@table @gcctabopt
+
+@item java.fullversion
+The combination of @code{java.vm.name} and @code{java.vm.version}.
+
+@item java.vm.info
+Same as @code{java.fullversion}.
+
+@item impl.prefix
+Used by the @code{java.net.DatagramSocket} class when set to something else
+then the empty string. When set all newly created @code{DatagramSocket}s will
+try to load a class @code{java.net.[impl.prefix]DatagramSocketImpl} instead of
+the normal @code{java.net.PlainDatagramSocketImpl}.
+
+@item gnu.gcj.progname
+The class or binary name that was used to invoke the program. This will be
+the name of the "main" class in the case where the @code{gij} front end is
+used, or the program binary name in the case where an application is compiled
+to a native binary.
+
+@item gnu.gcj.user.realname
+The real name of the user, as taken from the password file. This may
+not always hold only the user's name (as some sites put extra
+information in this field). Also, this property is not available on
+all platforms.
+
+@item gnu.gcj.runtime.NameFinder.use_addr2line
+Whether an external process, @command{addr2line}, should be used to determine
+line number information when tracing the stack. Setting this to @code{false}
+may suppress line numbers when printing stack traces and when using
+the java.util.logging infrastructure. However, performance may improve
+significantly for applications that print stack traces or make logging calls
+frequently.
+
+@item gnu.gcj.runtime.NameFinder.show_raw
+Whether the address of a stack frame should be printed when the line
+number is unavailable. Setting this to @code{true} will cause the name
+of the object and the offset within that object to be printed when no
+line number is available. This allows for off-line decoding of
+stack traces if necessary debug information is available. The default
+is @code{false}, no raw addresses are printed.
+
+@item gnu.gcj.runtime.NameFinder.remove_unknown
+Whether stack frames for non-java code should be included in a stack
+trace. The default value is @code{true}, stack frames for non-java
+code are suppressed. Setting this to @code{false} will cause any
+non-java stack frames to be printed in addition to frames for the java
+code.
+
+@item gnu.gcj.runtime.VMClassLoader.library_control
+This controls how shared libraries are automatically loaded by the
+built-in class loader. If this property is set to @samp{full}, a full
+search is done for each requested class. If this property is set to
+@samp{cache}, then any failed lookups are cached and not tried again.
+If this property is set to @samp{never} (the default), then lookups
+are never done. For more information, @xref{Extensions}.
+
+@item gnu.gcj.runtime.endorsed.dirs
+This is like the standard @code{java.endorsed.dirs}, property, but
+specifies some extra directories which are searched after the standard
+endorsed directories. This is primarily useful for telling
+@code{libgcj} about additional libraries which are ordinarily
+incorporated into the JDK, and which should be loaded by the bootstrap
+class loader, but which are not yet part of @code{libgcj} itself for
+some reason.
+
+@item gnu.gcj.jit.compiler
+@c FIXME we should probably have a whole node on this...
+This is the full path to @command{gcj} executable which should be
+used to compile classes just-in-time when
+@code{ClassLoader.defineClass} is called. If not set, @command{gcj}
+will not be invoked by the runtime; this can also be controlled via
+@code{Compiler.disable}.
+
+@item gnu.gcj.jit.options
+This is a space-separated string of options which should be passed to
+@command{gcj} when in JIT mode. If not set, a sensible default is
+chosen.
+
+@item gnu.gcj.jit.cachedir
+This is the directory where cached shared library files are
+stored. If not set, JIT compilation is disabled. This should never
+be set to a directory that is writable by any other user.
+
+@item gnu.gcj.precompiled.db.path
+This is a sequence of file names, each referring to a file created by
+@command{gcj-dbtool}. These files will be used by @code{libgcj} to
+find shared libraries corresponding to classes that are loaded from
+bytecode. @code{libgcj} often has a built-in default database; it
+can be queried using @code{gcj-dbtool -p}.
+
+@end table
+