- <para>With <option>-threaded</option>, calls to foreign
- functions are made using the same OS thread that created the
- Haskell thread (if it was created by a call to a foreign
- exported Haskell function), or an arbitrary OS thread
- otherwise (if the Haskell thread was created by
- <literal>forkIO</literal>).</para>
+ <varlistentry>
+ <term>
+ <option>-rtsopts</option>
+ <indexterm><primary><option>-rtsopts</option></primary></indexterm>
+ </term>
+ <listitem>
+ <para>
+ This option affects the processing of RTS control options given either
+ on the command line or via the <envar>GHCRTS</envar> environment variable.
+ There are three possibilities:
+ </para>
+ <variablelist>
+ <varlistentry>
+ <term><option>-rtsopts=none</option></term>
+ <listitem>
+ <para>
+ Disable all processing of RTS options.
+ If <option>+RTS</option> appears anywhere on the command
+ line, then the program will abort with an error message.
+ If the <envar>GHCRTS</envar> environment variable is
+ set, then the program will emit a warning message,
+ <envar>GHCRTS</envar> will be ignored, and the program
+ will run as normal.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>-rtsopts=some</option></term>
+ <listitem>
+ <para>[this is the default setting] Enable
+ only the "safe" RTS options: (Currently
+ only <option>-?</option>
+ and <option>--info</option>.) Any other RTS options
+ on the command line or in the <envar>GHCRTS</envar>
+ environment variable causes the program with to abort
+ with an error message.
+ </para>
+ </listitem>
+ </varlistentry>
+ <varlistentry>
+ <term><option>-rtsopts=all</option>, or
+ just <option>-rtsopts</option></term>
+ <listitem>
+ <para>
+ Enable <emphasis>all</emphasis> RTS option
+ processing, both on the command line and through
+ the <envar>GHCRTS</envar> environment variable.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+ <para>
+ In GHC 6.12.3 and earlier, the default was to process all
+ RTS options. However, since RTS options can be used to
+ write logging data to arbitrary files under the security
+ context of the running program, there is a potential
+ security problem. For this reason, GHC 7.0.1 and later
+ default to <option>-rtsops=some</option>.
+ </para>
+ </listitem>
+ </varlistentry>