Embedded Linux BOF

1
Embedded Linux BOF

• Tim Bird
• Software Engineer, Sony Electronics
• Chair, CE Linux Forum Architecture Group

2
Embedded Linux Stuff

• Year in Review
• Shameless plug
• Embedded Linux wiki
• Lightning talks

3
Year in Review

• Real-time
• Size
• Bootup Time
• Audio/Video/Graphics
• Security
• Power Management
• Mobile Phone
• Processor support
• Tools

4
Realtime

• hrtimers (2.6.18?)
• clock sources (2.6.18)
• HR timer API
• http//lwn.net/Articles/167315/
• ktimers explanation
• http//lwn.net/Articles/152436/
• Generic IRQ (2.6.18)
• Tickless Idle coming

5
Rt-Preempt

• Mainline status
• Most stuff in, only need
• sleeping spinlocks
• threaded IRQs
• Priority Inheritance (2.6.18)
• http//lwn.net/Articles/177838/
• Latency tracer

6
Size

• Linux-tiny
• Squashfs
• Inode Slimming
• Unit-at-a-time compilation
• Size Testing
• Bloatwatch
• Config size testing

7
Linx-tiny mainlining

• small-8023.patch
• fs_open-inlines.patch
• inode-inlines.patch
• fslocks-inline.patch
• bloat-o-meter.patch
• no-doublefault.patch
• no-elf-core.patch
• slob.patch
• remove-vm86.patch
• uid16.patch

8
Inode Slimming Patches

• brand new
• july 3 - Ted Tso (not mainlined yet)
• Tips
• Ted Tso - if you want to save memory taken up by
  in-core inodes, the first thing you should do is
  disable the debugging options they are
  responsible for a huge amount of bloat in the VFS
  inode structure

9
Unit-at-a-time Compilation

• Ingo Molnar patch to utilize gcc 4 unit-at-a-time
  compilation
• http//lkml.org/lkml/2005/12/28/68
• http//lwn.net/Articles/165354/
• inline reduction
• New _always_inline_ attribute
• http//lwn.net/Articles/167315/
• http//lwn.net/Articles/165354/

10
Size Testing

• Bloatwatch
• http//testlab.celinuxforum.org/...
• Config size testing
• Presentation at CELF Project BOF

11
Security

• AppArmour
• Lighter than SELinux
• Good enough for embedded work??
• LSM in peril

12
Bootup Time

• XIP - Execute in Place
• Old info http//lwn.net/Articles/135472/
• XAFS - new file system specifically for XIP
• Jared Hulbert (Intel) posted for comments
• http//lwn.net/Articles/182337/

13
Power Management

• User-space software suspend
• Latest kerfluffle over suspend phases
• Linus has posted a new patch, showing his method.
• See lwn.net http//lwn.net/Articles/189467
• Linux PM summit
• http//lwn.net/Articles/181687
• Main issues See PM BOF 1900 Room A

14
Audio/Video/Graphics

• Big direct rendering update
• http//lwn.net/Articles/167315/
• New CELF AVG Spec. (2.0)
• DirectFB, ALSA, OpenGL/ES, UHAPI

15
Mobile phone stuff

• CELF specification still in-progress
• More organizations than you can shake a stick
  at
• CELF MPPWG
• OSDL MLI
• LIPS
• the new one

16
Tools

• Tracing
• LTTgn just recently re-added lots of architecture
  support
• LTTng, KFT, LKST - See Tracing BOF, 1900 Room D
• Memory Leak Tracker
• Compilers
• Thumb support

17
Other

• Function re-ordering
• http//lwn.net/Articles/173657/
• GPL3
• Nothing to see here, move along

18
News from the Kernel Summit

• LSM stays for now
• suspend/resume still messed up
• no transparent super-pages
• Kernel leaders sympathetic to size issue
• other stuff??

19
Shameless plug

• CELF Project BOF
• Friday night, 700 pm, Les Suites
• CELF Test Lab demo
• Config size testing
• CABI CPU resource reservation
• Japan Jamboree update
• Technical showcase

20
Embedded Linux Wiki

• Place to store info on embedded Linux
• Starter material from CELF wiki
• Paid maintenance, to avoid wiki rot
• CELF may fund, if plan looks good and theres
  community interest
• BOF this week to discuss

21
Lightning talks

• 2 minutes (max)
• what are you doing? / what is the issue? when
  will you publish!?
• make it quick and to-the-point
• where to go for more info

22
Lightning topics