Document --enable-sandbox configure option in INSTALL.
diff --git a/INSTALL b/INSTALL
index fb2b6d7..da116be 100644
--- a/INSTALL
+++ b/INSTALL
@@ -399,6 +399,29 @@
calls any liblzma functions from more than
one thread, something bad may happen.
+ --enable-sandbox=METHOD
+ There is limited sandboxing support in the xz tool. If
+ built with sandbox support, it's used automatically when
+ (de)compressing exactly one file to standard output and
+ the options --files or --files0 weren't used. This is a
+ common use case, for example, (de)compressing .tar.xz
+ files via GNU tar. The sandbox is also used for
+ single-file `xz --test' or `xz --list'.
+
+ Supported METHODs:
+
+ auto Look for a supported sandboxing method
+ and use it if found. If no method is
+ found, then sandboxing isn't used.
+ This is the default.
+
+ no Disable sandboxing support.
+
+ capsicum
+ Use Capsicum (FreeBSD >= 10) for
+ sandboxing. If no Capsicum support
+ is found, configure will give an error.
+
--enable-symbol-versions
Use symbol versioning for liblzma. This is enabled by
default on GNU/Linux, other GNU-based systems, and
