[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>

diff --git a/arch/um/Kconfig b/arch/um/Kconfig
index 450547a4b3be9ece225ed836ff5c7c3edb7f2c90..78fb619bdb732fcf2bd6de5e99894840af5a3db8 100644 (file)
--- a/arch/um/Kconfig
+++ b/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
+       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"