rcu: Wordsmith help text for RCU_USER_QS kernel parameter

[karo-tx-linux.git] / init / Kconfig

diff --git a/init/Kconfig b/init/Kconfig
index 4c93533da42cbd66fd29f84b4e66c8c7e881c9ff..ec62139207d3cf5930a23d4f0642309864291a7c 100644 (file)
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -494,7 +494,13 @@ config RCU_USER_QS
          puts RCU in extended quiescent state when the CPU runs in
          userspace. It means that when a CPU runs in userspace, it is
          excluded from the global RCU state machine and thus doesn't
-         to keep the timer tick on for RCU.
+         try to keep the timer tick on for RCU.
+
+         Unless you want to hack and help the development of the full
+         tickless feature, you shouldn't enable this option.  It also
+         adds unnecessary overhead.
+
+         If unsure say N
 
 config RCU_USER_QS_FORCE
        bool "Force userspace extended QS by default"
@@ -504,6 +510,12 @@ config RCU_USER_QS_FORCE
          test this feature that treats userspace as an extended quiescent
          state until we have a real user like a full adaptive nohz option.
 
+         Unless you want to hack and help the development of the full
+         tickless feature, you shouldn't enable this option. It adds
+         unnecessary overhead.
+
+         If unsure say N
+
 config RCU_FANOUT
        int "Tree-based hierarchical RCU fanout value"
        range 2 64 if 64BIT
@@ -570,14 +582,13 @@ config RCU_FAST_NO_HZ
        depends on NO_HZ && SMP
        default n
        help
-         This option causes RCU to attempt to accelerate grace periods
-         in order to allow CPUs to enter dynticks-idle state more
-         quickly.  On the other hand, this option increases the overhead
-         of the dynticks-idle checking, particularly on systems with
-         large numbers of CPUs.
+         This option causes RCU to attempt to accelerate grace periods in
+         order to allow CPUs to enter dynticks-idle state more quickly.
+         On the other hand, this option increases the overhead of the
+         dynticks-idle checking, thus degrading scheduling latency.
 
-         Say Y if energy efficiency is critically important, particularly
-               if you have relatively few CPUs.
+         Say Y if energy efficiency is critically important, and you don't
+               care about real-time response.
 
          Say N if you are unsure.
 
@@ -1562,6 +1573,66 @@ config MODULE_SRCVERSION_ALL
          the version).  With this option, such a "srcversion" field
          will be created for all modules.  If unsure, say N.
 
+config MODULE_SIG
+       bool "Module signature verification"
+       depends on MODULES
+       select KEYS
+       select CRYPTO
+       select ASYMMETRIC_KEY_TYPE
+       select ASYMMETRIC_PUBLIC_KEY_SUBTYPE
+       select PUBLIC_KEY_ALGO_RSA
+       select ASN1
+       select OID_REGISTRY
+       select X509_CERTIFICATE_PARSER
+       help
+         Check modules for valid signatures upon load: the signature
+         is simply appended to the module. For more information see
+         Documentation/module-signing.txt.
+
+         !!!WARNING!!!  If you enable this option, you MUST make sure that the
+         module DOES NOT get stripped after being signed.  This includes the
+         debuginfo strip done by some packagers (such as rpmbuild) and
+         inclusion into an initramfs that wants the module size reduced.
+
+config MODULE_SIG_FORCE
+       bool "Require modules to be validly signed"
+       depends on MODULE_SIG
+       help
+         Reject unsigned modules or signed modules for which we don't have a
+         key.  Without this, such modules will simply taint the kernel.
+
+choice
+       prompt "Which hash algorithm should modules be signed with?"
+       depends on MODULE_SIG
+       help
+         This determines which sort of hashing algorithm will be used during
+         signature generation.  This algorithm _must_ be built into the kernel
+         directly so that signature verification can take place.  It is not
+         possible to load a signed module containing the algorithm to check
+         the signature on that module.
+
+config MODULE_SIG_SHA1
+       bool "Sign modules with SHA-1"
+       select CRYPTO_SHA1
+
+config MODULE_SIG_SHA224
+       bool "Sign modules with SHA-224"
+       select CRYPTO_SHA256
+
+config MODULE_SIG_SHA256
+       bool "Sign modules with SHA-256"
+       select CRYPTO_SHA256
+
+config MODULE_SIG_SHA384
+       bool "Sign modules with SHA-384"
+       select CRYPTO_SHA512
+
+config MODULE_SIG_SHA512
+       bool "Sign modules with SHA-512"
+       select CRYPTO_SHA512
+
+endchoice
+
 endif # MODULES
 
 config INIT_ALL_POSSIBLE
@@ -1595,4 +1666,12 @@ config PADATA
 config BROKEN_RODATA
        bool
 
+config ASN1
+       tristate
+       help
+         Build a simple ASN.1 grammar compiler that produces a bytecode output
+         that can be interpreted by the ASN.1 stream decoder and used to
+         inform it as to what tags are to be expected in a stream and what
+         functions to call on what tags.
+
 source "kernel/Kconfig.locks"