Technology Watch List

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This page lists technologies and projects that CELF members are interested in the status of. This includes kernel patches, new technology research, and middleware and user-space projects of key interest for consumer electronics products. The projects may be the topics of discussion at CELF meetings, and we plan to watch and report the status of these technologies.

Please add any information you have about the technology items listed below!!

Latest Watchlist

The Status field in the table below indicates whether this feature is on track for being mainlined. The When was last activity field indicates the kernel version number or date when the last activity was noted for this feature. This could be the last kernel version where bits from this patch were mainlined, or the last date of visible feature development activity outside the main tree.

Kernel Stuff

Size Stuff

Technology, Feature or Patch Status When was last activity Notes
Linux-tiny In active maintenance. Path set published for 2.6.24 Latest full patchset was published Oct. 13, 2007, Latest patch (CONSOLE_TRANSLATIONS) was mainlined in June 2008 Maintainer is Michael Opdenacker (with help from Thomas Petazzoni). See Linux Tiny Patch Details for details about the patch status.
kpagemap - memory instrumentation mainlined in Feb, 2008 (for 2.6.25) Feb 2008
Bloatwatch (2.0) Now actively reporting kernel sizes April 2008 See Matt's presentation from ELC 2008
gcc -ffunction-sections -fdata-sections Patches submitted to LKML July 2008 See Function sections

File Systems

Technology, Feature or Patch Status When was last activity Notes
Squash Fs Latest release is 3.4, released Aug 26, 2008 (See Squashfs 3.4 released. Most recent mainline mainline submission was in October 2008 Another mainline attempt is in progress Phillip is working on another mainline attempt, with CELF funding. Sony is trying to help with the effort.
AXFS Not mainlined. Some required (predecessor) bits were mainlined in March, 2008, A version was submitted to LKML in August 2008 Flash filesystem that allows for tuning the amount of XIP
LogFS Not mainlined. Last mainline attempt was May, 2008.
  • Home page is at:
  • Jörn Engel is working on a re-write to address several major issues.
  • CELF is funding this work.
UBIFS mainlined in 2.6.27


Tracing and instrumentation

Technology, Feature or Patch Status When was last activity Notes
LTTng core not mainlined. Markers were mainlined in 2.6.24 ? LTTng instrumentation was changed to use markers, in early 2007
SystemTap (and Kprobes) for non-i386 arches ARM support merged for 2.6.25 ? KProbes ports for ARM, MIPS and PPC32 were reported on at ELC 2007, SystemTap for SH was demo'ed at ELC 2007
Kernel Function Trace (KFT) not mainlined Last published patches for 2.6.22 Nicholas McGuire was taking over maintainership from Tim Bird, with funding from CELF. Haven't heard much recently (as of June 2008)
ftrace mainlined in 2.6.27 This was formerly the latency-trace features from the RT-preempt patch set, refactored for general use
printk-times (arch support) fully mainlined? April, 2005 Some arches had problems with accessing the clock too early in the kernel bootup sequence, but a new setup routine defers turning on the timestamping until after timekeeping is initialized


Technology, Feature or Patch Status When was last activity Notes
KTimers mainlined, but needs lots of porting to embedded architectures ?? Adding clock driver support for various architectures is an ongoing process
RT-preempt some parts mainlined (last part was high res. timers in 2.6.21) 2.6.21? Next target is to integrate threaded interrupts in 2.6.23?? Threaded interrupt still not in 2.6.25
Xenomai external project 2.6.25 - stable release, newer in development Xenomai is a real-time development framework cooperating with the Linux kernel, in order to provide a pervasive, interface-agnostic, hard real-time support to user-space applications, seamlessly integrated into the GNU/Linux environment. Ready to deploy.


Technology, Feature or Patch Status When was last activity Notes
App Armour not mainlined May, 2007
TOMOYO Linux not mainlined Nov 17, 2007 (4th post) (trying now) "TOMOYO Linux has only recently surfaced on the wider mailing lists; its reception has not been entirely friendly. This project's developers have some work to do if they are (1) to get past the same obstacles which have slowed AppArmor, and (2) show that their project is sufficiently different from AppArmor to merit inclusion as yet another security framework." (from Linux Weather Forecast)
SMACK mainlined in 2.6.25 . article on SMACK
SELinux (usable in embedded) SELinux is mainlined, but some issues for making SELinux usable for embedded remain April 2008
  • There has been much progress recently to support SELinux in the embedded space
  • Requires filesytem with xattrs (some flash filesystems do not support xattrs)
  • at ELC 2008, Yuichi Nakamura described an embedded configuration of SELinux in as little as 700K

Power Management

Technology, Feature or Patch Status When was last activity Notes
powertop support for powertop is mainlined (for x86 architecture) ?
  • Powertop shows timers and power state durations
  • Only well-supported on x86??
    • To support on other architectures, the platform needs to support CPUIdle interface, in order to show C-state (power state) ** There has been some activity for non-Intel processors
PM QoS in 2.6.23-mm1 Oct '07 (see need Embedded folks to take a look and help define the interface, expand the features and raise issues from the embedded perspective.
Wolfson voltage regulator stuff not mainlined?? March 2008? See Every Microamp is Sacred - A Dynamic Voltage and Current Control Interface for the Linux Kernel - Liam Girdwood's ELC 2008 presentation

Bootup Time

Technology, Feature or Patch Status When was last activity Notes
deferred module load not mainlined, no patches July 2008 Proposed, without patches, by Tim Bird on linux-embedded list
async initcalls not mainlined July 2008 Patches submitted by Arjan van de Ven
snapshot boot not mainlined July 2006 Sony presented paper at OLS 2006. This technology is used in Sony products.
fastboot kernel configuration option not mainlined? July 2006 Arjan van de Ven submitted as part of his async initcalls patches


Technology, Feature or Patch Status When was last activity Notes
Userspace I/O Seems to be merged into mainline (see: ) July, 2007 References:


Project Status When was last activity Notes
libdlna Developer has added support for all profiles except MPEG-4 and WMV ( ) 29 Aug, 07 Short term goal is to provide DLNA support to Ushare media server, long term goal is to provide generic DLNA reference library