pty.7: Explicitly mention CONFIG_LEGACY_PTYS

Explicitly mention CONFIG_LEGACY_PTYS, and note that it is disabled
by default since Linux 2.6.30.

Signed-off-by: Michael Kerrisk <mtk.manpages@gmail.com>

diff --git a/man7/pty.7 b/man7/pty.7
index f321b9395d6307d5b8c83d85d3d91e11a1d865eb..ecc1a6bec6ba44446f9fe5aadec81d3b0f7e03fd 100644 (file)
--- a/man7/pty.7
+++ b/man7/pty.7
@@ -66,8 +66,13 @@ Linux provides both BSD-style and (standardized) System V-style
 pseudoterminals.
 System V-style terminals are commonly called UNIX 98 pseudoterminals
 on Linux systems.
-Since kernel 2.6.4, BSD-style pseudoterminals are considered deprecated
-(they can be disabled when configuring the kernel);
+.PP
+Since kernel 2.6.4, BSD-style pseudoterminals are considered deprecated:
+support can be disabled when building the kernel by disabling the
+.B CONFIG_LEGACY_PTYS
+option.
+(Starting with Linux 2.6.30,
+that option is disabled by default in the mainline kernel.)
 UNIX 98 pseudoterminals should be used in new applications.
 .SS UNIX 98 pseudoterminals
 An unused UNIX 98 pseudoterminal master is opened by calling