[PATCH] uml: Adds LEGACY_PTY config option

The second adds the LEGACY_PTY config option. Without it, with late 2.6 kernels
/dev/ptyxx won't work. In fact, with those kernels, root_fs_toms does not
work, because it's "unable to allocate TTY pair". And removes the dead option 
"UNIX98_PTY_COUNT" (just commented out for now).
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade_spam@yahoo.it>
Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

arch/um/Kconfig_char

@@ -108,11 +108,60 @@ config SSL_CHAN
 
 config UNIX98_PTYS
 	bool "Unix98 PTY support"
-
-config UNIX98_PTY_COUNT
-	int "Maximum number of Unix98 PTYs in use (0-2048)"
-	depends on UNIX98_PTYS
+	---help---
+	  A pseudo terminal (PTY) is a software device consisting of two
+	  halves: a master and a slave. The slave device behaves identical to
+	  a physical terminal; the master device is used by a process to
+	  read data from and write data to the slave, thereby emulating a
+	  terminal. Typical programs for the master side are telnet servers
+	  and xterms.
+
+	  Linux has traditionally used the BSD-like names /dev/ptyxx for
+	  masters and /dev/ttyxx for slaves of pseudo terminals. This scheme
+	  has a number of problems. The GNU C library glibc 2.1 and later,
+	  however, supports the Unix98 naming standard: in order to acquire a
+	  pseudo terminal, a process opens /dev/ptmx; the number of the pseudo
+	  terminal is then made available to the process and the pseudo
+	  terminal slave can be accessed as /dev/pts/<number>. What was
+	  traditionally /dev/ttyp2 will then be /dev/pts/2, for example.
+
+	  All modern Linux systems use the Unix98 ptys.  Say Y unless
+	  you're on an embedded system and want to conserve memory.
+
+config LEGACY_PTYS
+	bool "Legacy (BSD) PTY support"
+	default y
+	---help---
+	  A pseudo terminal (PTY) is a software device consisting of two
+	  halves: a master and a slave. The slave device behaves identical to
+	  a physical terminal; the master device is used by a process to
+	  read data from and write data to the slave, thereby emulating a
+	  terminal. Typical programs for the master side are telnet servers
+	  and xterms.
+
+	  Linux has traditionally used the BSD-like names /dev/ptyxx
+	  for masters and /dev/ttyxx for slaves of pseudo
+	  terminals. This scheme has a number of problems, including
+	  security.  This option enables these legacy devices; on most
+	  systems, it is safe to say N.
+
+
+config LEGACY_PTY_COUNT
+	int "Maximum number of legacy PTY in use"
+	depends on LEGACY_PTYS
 	default "256"
+	---help---
+	  The maximum number of legacy PTYs that can be used at any one time.
+	  The default is 256, and should be more than enough.  Embedded
+	  systems may want to reduce this to save memory.
+
+	  When not in use, each legacy PTY occupies 12 bytes on 32-bit
+	  architectures and 24 bytes on 64-bit architectures.
+
+#config UNIX98_PTY_COUNT
+#	int "Maximum number of Unix98 PTYs in use (0-2048)"
+#	depends on UNIX98_PTYS
+#	default "256"
 
 config WATCHDOG
 	bool "Watchdog Timer Support"