UDS Developments

[Ralf Mardorf]

On Tue, 2012-05-08 at 20:27 +0200, Kaj Ailomaa wrote:
> What do mean by a "full" preempt non-rt kernel?

The first three kernels are full preempt, not voluntary. With full
preempt I mean that it's the most hard real-time kernel of all preempt
non-rt kernels. You can build it without a patch-rt, those are simple
vanilla kernels. The default lowlatency or avl might have distro
specific patches, that shouldn't be related to preemption.
The fourth kernel is a kernel-rt, providing harder real-time than a full
preempt kernel. To build a kernel preempt rt you need a patch-rt.

Vanilla kernels that can be configured for different kinds of
preemption:
http://www.kernel.org/pub/linux/kernel/v3.x/
The patches that are needed to get the preempt rt kernels:
http://www.kernel.org/pub/linux/kernel/projects/rt/

spinymouse at precise:~$ grep PREEMPT /boot/config-3.0.30
CONFIG_TREE_PREEMPT_RCU=y
CONFIG_PREEMPT_RCU=y
CONFIG_PREEMPT_NOTIFIERS=y
# CONFIG_PREEMPT_NONE is not set
# CONFIG_PREEMPT_VOLUNTARY is not set
CONFIG_PREEMPT=y
# CONFIG_PREEMPT_TRACER is not set
spinymouse at precise:~$ grep PREEMPT /boot/config-3.2.0-23-lowlatency
CONFIG_TREE_PREEMPT_RCU=y
CONFIG_PREEMPT_RCU=y
CONFIG_PREEMPT_NOTIFIERS=y
# CONFIG_PREEMPT_NONE is not set
# CONFIG_PREEMPT_VOLUNTARY is not set
CONFIG_PREEMPT=y
CONFIG_PREEMPT_COUNT=y
# CONFIG_PREEMPT_TRACER is not set
spinymouse at precise:~$ grep
PREEMPT /media/avlinux/boot/config-3.0.23-avl-7-pae
CONFIG_TREE_PREEMPT_RCU=y
CONFIG_PREEMPT_RCU=y
CONFIG_PREEMPT_NOTIFIERS=y
# CONFIG_PREEMPT_NONE is not set
# CONFIG_PREEMPT_VOLUNTARY is not set
CONFIG_PREEMPT=y
# CONFIG_DEBUG_PREEMPT is not set
spinymouse at precise:~$ grep
PREEMPT /media/avlinux/boot/config-3.0.23-rt40
CONFIG_TREE_PREEMPT_RCU=y
CONFIG_PREEMPT_RCU=y
CONFIG_PREEMPT_NOTIFIERS=y
CONFIG_PREEMPT=y
CONFIG_PREEMPT_RT_BASE=y
# CONFIG_PREEMPT_NONE is not set
# CONFIG_PREEMPT_VOLUNTARY is not set
# CONFIG_PREEMPT_LL is not set
# CONFIG_PREEMPT_RTB is not set
CONFIG_PREEMPT_RT_FULL=y