Status of Embedded Linux

CE WorgroupWork Update

May 2011

Tim Bird

Architecture Group Chair

LF CE Workgroup

Outline

• Status of merger with Linux Foundation• CELF contract work• Review of 2010 work• Plan for 2011 work

• Conferences• Other meetings

• Other initiatives

Merger Status

Merger with Linux Foundation

• Merger was completed in January 2011• Some final legal details still being wrapped

up• CELF is now the Linux Foundation “CE

Workgroup”• Now starting to utilize Linux Foundation

infrastructure– Should mean it's easier for non-members

to participate in CE WG projects!

Contract Work 2010

CELF Contract Work 2010

• Bootchart and smemcap in busybox• Function-sections• YAFFS2 mainline effort• SquashFS enhancements• U-Boot ARM enhancements• Trace format standard• Kexecboot enhancements• Flash filesystem testing

Bootchart and smemcap support in busybox Smemcap applet

• Bootchart applet - Captures bootchart data• See

http://elinux.org/Japan_Technical_Jamboree_33• See http://elinux.org/Bootchart#BusyBox

• Smemcap applet – captures smem data• Data can be moved to host for analysis and

visualization• Contractor: Denys Vlasenko• Status: Completed• Applets are available in busybox mainline

Function-sections

• Description:• Add support to Linux kernel for gcc –ffunction-

sections option, to shrink kernel size by improving dead code removal• Puts each function in its own linker section• Required a big section rename in kernel

• Contractor: Denys Vlasenko• Status:• Most parts mainlined• Waiting to resolve linker issues for weird

symbols on PARISC• Effort stalled – need to finish it

Mainline YAFFS2

• Description:• YAFFS2 is a popular NAND flash filesystem• Was used by Android in many devices

• Add support for YAFFS2 to mainline kernel• Contractor: Aleph One Ltd• Google Co-Sponsored this project• Status:• 3 mainline attempts made, but hit some barriers• Currently stuck on some locking issues

• Outlook for mainline acceptance is uncertain

SquashFS LZMA/LZO Support

Description: LZMA and LZO support

Contractor: Phillip Lougher Status:

LZMA work was submitted, and was in Linux-next, but got rejected

LZO work (contributed by LGE) was mainlined!!

ARM improvements in U-boot

• Description:• Improve aspects of U-boot for ARM• Allow relocating bootloader• Turn caches on for faster booting

• Contractor: Wolfgang Denx• Status:• Work was completed and mainlined in U-Boot

U-Boot Results:

• Limit for boot time into app code is 5s so U-boot image compression was not possible. But now it is.• Results from Matthias Weißer on Aug 5, 2010

• See http://article.gmane.org/gmane.comp.boot-loaders.u-boot/82079

Test Old (icache) New (i+d cache

Improvement

U-boot image size 191K 204K -

Copy 32M NOR -> RAM 7.0s 6.5s x 1.07

iminfo of 1.2 MiB image 0.5s 0.1s x 5.0

bootm of 1.2 MiB gz image 5.4s 0.5s x 10.8

Bootm of 0.8 MiB lzma image 17,1s 1.5s x 11.4

Bootm of 1.6 MiB lzo image 3.2s 0.2s x 16.0

Trace format standard

• Description:• Create a singled trace format standard for the

embedded industry• Contractor: Efficios (Matthieu Desnoyers)• Status:• Standard (Common Trace Format) was created• See http://www.efficios.com/ctf

• BabelTrace trace conversion library• Proof of concept conversion implementation

– Can convert kernel messages with timestamps to CTF and back to text

Kexecboot improvements

Description: Improve user interface and supported storage

devices for kexecboot Contractor: Yuri Bushmelev Status:

Interface has been enhanced Work on reading other storage devices was

completed

Flash filesystem testing

Description: Measure different flash filesystems for

comparisons Contractor: Free Electrons Status:

Results were shown at ELC Europe 2010

Contract Work 2011

Open Project Proposal

• Project ideas were collected in Dec. 2010 and Jan. 2011

• Bids were solicited in March• Architecture Group approved projects in April– 11 projects approved out of 28– Still have budget for more projects

• Contracts are being finalized now• Have a good list, but would like more

proposals from CE WG/LF members

Contract Work 2011

• Improve UBIFS mount time• Mainline Android kernel features• Mainline fast symbol resolution• Work on Linux tiny patches• Support read-only block filesystems on flash

devices

Contract Work 2011 (cont.)

• eLinux wiki content for kernel trace and debug• Mainline the watchdog framework• Flash filesystem testing• Extend bluetooth stack with Remote SIM

Access protocol• Mainline Device Firmware Upgrade (DFU)

code in U-Boot• Solicit project proposals throughout year

Improve UBIFS mount time

• Description:• Add logging or checkpointing to UBI to avoid bad-

block scan of whole device on UBI attach• Contractor: Linutronix (Thomas Gleixner)• Status:• Contract almost finished

Mainline Android kernel features

• Description:• Add a single Android feature (logger) to mainline,

as a pilot project for 3rd party mainlining of Android code

• Longterm goal is to mainline as much of Android as possible, to reduce difference and allow for easier “unified distro kernel”• Kernel that can run Ubuntu, Android, etc.

• Contractor: have interest from Alessio Bogani• Status:• Still working on project plan and bid

Mainline fast symbol resolution

• Description:• Change symbol lookup to use binary search

instead of linear scan• Speeds up module loading

• Contractor: Alessio Bogani• Status:• Patches are in linux-next

Work on Linux tiny patches

Description: Revive Linux-tiny patch set Forward-port patches to latest kernel Add more patches to improve kernel

configurability Contractor: We Zhanjin Status:

Contract ready to sign

Support read-only block filesystems on flash media

Description: Write block emulation layer to support read-only

filesystems on top of MTD layer in kernel Will allow Squashfs to be used on raw NAND

flash media Contractor: Phillip Lougher Status:

Contract in progress

eLinux wiki content for trace and debug

Description: Collect content on kernel trace and debug

techniques and publish on eLinux wiki Contractor: Peter Huewe Status:

Contract ready to sign

Mainline the watchdog framework

Description: Mainline the watchdog framework Original framework was written by Alan Cox and

others Provides a generalized watchdog mechanism Should provide easier method to add

watchdogging to drivers and the kernel going forward

Contractors: Wolfram Sang and Wim van Sebroeck

Status: Contract ready to sign

Flash filesystem testing

Description: Perform mount and runtime performance tests on

multiple flash filesystems, for each new kernel release

Publish results on eLinux wiki Contractor: Free Electrons Status:

Contract ready to sign

Extend bluetooth stack with Remote SIM Access protocol

Description: Allows for Linux bluetooth and telephony stack to

utilize SIM in external device for operation Primary use case is for Linux-based in-car system

to utilize SIM in mobile device for calls, etc. Contractor: ProFusion Status:

Contract almost complete

Mainline Device Firmware Upgrade (DFU) code in U-Boot

Description: Device Firmware Upgrade (DFU) is an industry

standard system for upgrading and manipulating firmware in embedded devices

Add support for this protocol to U-Boot mainline Contractor: Stefan Schmidt Status:

Contract ready to sign

Solicit project proposals throughout the year

Description: CE Workgroup will continue to maintain the

Project Proposal wiki page, and will continue accepting ideas and proposals for contract work through 2011

This will allow ideas to come in as they are generated and relevant, instead of accumulating them throughout the year

Contractor: Bill Traynor Status:

Contract ready to sign

Conferences

Conferences

Past

– ELC 2011 and Android Builders Summit

• Videos just announced – see wiki page

• Kato-san will give a report later today Future

LinuxCon Japan – June 1-3, Yokohama ELC Europe 2011 – Oct 26-28, Prague LinuxCon Brazil – Nov 17-18, Sao Paulo Continuing Japan Jamborees ELC and Android Builders Summit in 2012

See http://events.linuxfoundation.com/ and http://elinux.org/events

Embedded Linux Summit

• Invitation-only event to discuss embedded issues between key industry and community leaders• Was held September 30, 2010 in Tokyo and

October 26 in Cambrige, UK• Similar to other mini-summits, but with focus

on embedded issues• Leading up to kernel summit in November– Has lead to several initiatives– Big one was longterm kernel branch,

maintained by Andi Kleen

Android mainline BOF

• Invitation-only event to discuss Android mainline issues• Was held April 14 in San Francisco– Linaro, CE WG, Google and Qualcomm

attended• Very good discussion about what different

members of the “Android/Linux ecosystem” could do to coordinate work and mainline Android technologies• CE WG “mainline Android logger” project is a

result of this meeting

Other Initiatives

eLinux Wiki

• http://elinux.org/• Wikipedia for embedded Linux developers• Very good for some technical areas• I have been working on Android Portal

section of site• Recently moved to OSU Open Source Lab

hosting• Promotion• Contest – just finished best editor contest!

• Please use it and post stuff

Hardware Donations

• CELF donates hardware for some open source developers• example: Board for BKL removal work

• E-mail me if you need hardware for a project that you think CELF would be interested in

Thanks!