Download ppt - Embedded Linux BOF

April 22, 2023 CE Linux Forum Members Confidential

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Embedded Linux BOF

Tim BirdSoftware Engineer, Sony ElectronicsChair, CE Linux Forum Architecture

Group


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Embedded Linux Stuff• Year in Review

• Shameless plug

• Embedded Linux wiki

• Lightning talks


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Year in Review

• Real-time

• Size

• Bootup Time

• Audio/Video/Graphics

• Security

• Power Management

• Mobile Phone

• Processor support

• Tools


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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

http://lwn.net/Articles/167315/



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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


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Size

• Linux-tiny

• Squashfs

• Inode Slimming

• Unit-at-a-time compilation• Size Testing

– Bloatwatch

– Config size testing


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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


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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


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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:




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Size Testing• Bloatwatch

– http://testlab.celinuxforum.org/...

• Config size testing– Presentation at CELF Project BOF


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Security• AppArmour

– Lighter than SELinux– Good enough for embedded work??

• LSM in peril…


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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/



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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 19:00 Room A


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Audio/Video/Graphics

• Big direct rendering update

– http://lwn.net/Articles/167315/

• New CELF AVG Spec. (2.0)– DirectFB, ALSA, OpenGL/ES, UHAPI



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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”


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Tools• Tracing

– LTTgn just recently re-added lots of architecture support

– LTTng, KFT, LKST - See Tracing BOF, 19:00 Room D

• Memory Leak Tracker

• Compilers– Thumb support


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Other• Function re-ordering

– http://lwn.net/Articles/173657/

• GPL3– “Nothing to see here, move along…


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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??


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Shameless plug• CELF Project BOF

– Friday night, 7:00 pm, Les Suites– CELF Test Lab demo– Config size testing– CABI CPU resource reservation– Japan Jamboree update– Technical showcase


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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 there’s

community interest

• BOF this week to discuss


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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…


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Lightning topics