Module: xenomai-2.6
Branch: master
Commit: 44ae881fd9022914cce689e51c4b274575bce735

Author: Philippe Gerum <>
Date:   Wed May 23 23:14:38 2012 +0200

nucleus: deprecate priority coupling

This feature does not fully deliver the initial promise of boosting
the linux kernel priority in every circumstance requiring it (granted,
only in a few uncommon cases, but still).

However, it still has a measurable impact on latency during primary
<-> secondary mode switches, although some progress has been made in
this area. Besides, it became overly complex over time to maintain, as
more issues where discovered and fixed, compared to the fairly small
number of use cases which might actually benefit from it.

For these reasons, we have already pulled this feature out from the
Xenomai 3 core. It is now marked as deprecated in 2.6.x as well and
defaults to disabled, to give a clear hint that applications should
not depend on it.

The short version is: 'Darn, I was wrong'.


 ksrc/nucleus/Kconfig |    8 +++++---
 1 files changed, 5 insertions(+), 3 deletions(-)

diff --git a/ksrc/nucleus/Kconfig b/ksrc/nucleus/Kconfig
index e058577..b53cbfc 100644
--- a/ksrc/nucleus/Kconfig
+++ b/ksrc/nucleus/Kconfig
@@ -21,8 +21,8 @@ config XENO_OPT_PERVASIVE
        depends on XENO_OPT_PERVASIVE
-       bool "Priority coupling support"
-       default y
+       bool "Priority coupling support (DEPRECATED)"
+       default n
        This option builds in the priority coupling support between
@@ -51,7 +51,9 @@ config XENO_OPT_PRIOCPL
        support globally. Otherwise, no priority coupling will ever
-       If in doubt, say Y.
+       Most applications do not require priority coupling, and should
+       leave this option disabled, unless you really know what you
+       are doing. If in doubt, say N.
        bool "Optimize as pipeline head (DEPRECATED)"

Xenomai-git mailing list

Reply via email to