Linux Bootup Time Reduction for Digital Still Camera.ppt
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1、Linux Bootup Time Reduction for Digital Still Camera,Chan Ju, Park SW Laboratories Samsung Electronics,Introduction DSC Bootup Procedure Bootup time reduction methods Boot loader Kernel Root File system Application Optimization Suspend/resume Results Further works Conclusion,Agenda,terms,DSC Digital
2、 still camera Bootup time The time from platform power on to preview state Preview state The DSC state for ready-to-shot 3A Auto focus, auto white balance, auto expose Suspend/resume Suspend to dram RFS Root file system for Linux Kernel Robust FS Linux file system for OneNAND flash Normal boot, susp
3、end/resume boot,introduction,About this project In samsung, Embedded Linux ported for many CE devices DTV, DMB, Mobile phone, DVR, other set top boxes, etc But not DSC area DSC use many RTOSes ( vxworks, pSos, uITRON, Nucleus, etc) Project stated for evaluation of embedded linuxWhy Linux in DSC Tech
4、nical Convergence in CE Devices Plentiful of Application Open S/W Platform Cost?,Embedded Linux on DSC There exist only few cases which was published E.g. Ricoh Company made prototype Linux DSCDSC & bootup time Long bootup time diminish customer satisfaction Bootup Time is more important in DSC,Linu
5、x Bootup Time PC : 1 min or more Embedded System : 210 sec Depends on system, Applications, Policy Image loading, H/W peripherals, application initapplied Bootup methods for DSC Normal Boot bootloader preview application running Suspend/Resume using suspend-to-ramGoals Normal boot : 2 sec Suspend/re
6、sume : 1 sec,Test Environments,Target Platform Core ARM926EJS Image processor Samsung S5C7380x System clock 216Mhz Fclock,108Mhz Hclock Memory 64MB DDR, 64MB One-NAND flash ( async mode )DSC Module & etc 6M CCD(CMOS) censor, AF/Zoom/Shutter/Iris motor, Digital LCD, JPEG/MPEG codec, etc. USB, ADC, SD
7、/MMC Card, etc,Kernel 2.4.20 Non-compressed Image Size : about 1MBFile System Root fs : Cramfs Robust FS for Flash filesystem in OneNAND,Bootup time reduction is,Every little makes a mickle All kinds of techniques are needed Firmware (boot loader) Minimal system init shortening image copy time Boot
8、devicesHardware initialization One time System initialization Remove H/W probing time Only initialize the device which was used when bootup E.g. Dsc motors, storage (HDD, Card, Flash), DSP, etc,Image small sizing kernel, root fs (libraries), D/D Modules, etc Depends on the kernel configurationDevice
9、 driver initialization Remove H/W probing & Initialization Using hard coding Module loading policy Using static module if needed Other modules can load when neededapplication optimization Resource loading Memory allocation App setup procedureSuspend/resume,DSC Booting Procedure,bootloader reset OneN
10、AND boot loader(xloader) execute xloader copied to SDRAM & execute at SDRAM xloader copy u-boot to RAM DSC motor init u-boot execute & copy kernel Image to SDRAMkernel init Kernel Init code execute init kernel subsystem init static module mount cramfs execute init scriptapplication init execute basi
11、c DSC application module setup preview mode sequence display preview & OSD Image,Boot time measurements,Using H/W devices Expensive Target code modification is needed ExactUsing serial outputs ARM or MIPS has no counter register (x86:TSC reg.) Using host serial in cross development environments feat
12、ures Cheap No or few modification for the target code Can collect much data Comparatively small differences,Initial bootup time (before optimization),Just after kernel and D/D porting Using NAND flash, zImage,Applied methods,Normal bootup bootloader OneNAND booting (more faster than Nand flash, 2 ti
13、mes) Kernel / device driver use Preset LJP (Loop Per Jiffies) module init optimization use non-compressed kernel image size optimization ( kernel, library ) remove kernel message File system application optimizationSuspend/resume,Not using u-boot except development period Boot loader initializes a s
14、ystem loads the Kernel image into RAM Minimal initialization Memory, clockBoot device NAND Flash OneNAND Flash When power on, xloader (1KB bootloader of OneNAND flash) is executed automatically hardly influence to bootup time More fast than nand flash (2 times),Boot loader,Flash Partition Usage (One
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