[PATCH] uml: deprecate CONFIG_MODE_TT

Deprecate TT mode in Kconfig so that users won't select it, update the
MODE_SKAS description (it was largely obsolete and misleadin) and btw describe
advantages for high memory usage with CONFIG_STATIC_LINK.
Signed-off-by: Paolo 'Blaisorblade' Giarrusso <blaisorblade@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

@@ -50,13 +50,15 @@ config IRQ_RELEASE_METHOD
 menu "UML-specific options"
 
 config MODE_TT
-	bool "Tracing thread support"
+	bool "Tracing thread support (DEPRECATED)"
 	default n
 	help
 	This option controls whether tracing thread support is compiled
 	into UML. This option is largely obsolete, given that skas0 provides
 	skas security and performance without needing to patch the host.
-	It is safe to say 'N' here.
+	It is safe to say 'N' here; saying 'Y' may cause additional problems
+	with the resulting binary even if you run UML in SKAS mode, and running
+	in TT mode is strongly *NOT RECOMMENDED*.
 
 config STATIC_LINK
 	bool "Force a static link"
@@ -69,6 +71,9 @@ config STATIC_LINK
 	for use in a chroot jail.  So, if you intend to run UML inside a
 	chroot, and you disable CONFIG_MODE_TT, you probably want to say Y
 	here.
+	Additionally, this option enables using higher memory spaces (up to
+	2.75G) for UML - disabling CONFIG_MODE_TT and enabling this option leads
+	to best results for this.
 
 config KERNEL_HALF_GIGS
 	int "Kernel address space size (in .5G units)"
@@ -85,10 +90,13 @@ config MODE_SKAS
 	default y
 	help
 	This option controls whether skas (separate kernel address space)
-	support is compiled in.  If you have applied the skas patch to the
-	host, then you certainly want to say Y here (and consider saying N
-	to CONFIG_MODE_TT).  Otherwise, it is safe to say Y.  Disabling this
-	option will shrink the UML binary slightly.
+	support is compiled in.
+	Unless you have specific needs to use TT mode (which applies almost only
+	to developers), you should say Y here.
+	SKAS mode will make use of the SKAS3 patch if it is applied on the host
+	(and your UML will run in SKAS3 mode), but if no SKAS patch is applied
+	on the host it will run in SKAS0 mode, which is anyway faster than TT
+	mode.
 
 source "arch/um/Kconfig.arch"
 source "mm/Kconfig"