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Some Experience A bout μ kernel and Device Driver

Some Experience A bout μ kernel and Device Driver. 970529 Sean Lin. Outline. Introduction of μ kernel Introduction of L4 μ kernel Family Something Interesting in L4 μ kernel Introduction of T he Platform The Bug of USB Host Device Driver Other Experiences of Driver Debugging.

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Some Experience A bout μ kernel and Device Driver

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  1. Some Experience About μkernel and Device Driver 970529 Sean Lin

  2. Outline • Introduction of μkernel • Introduction of L4 μkernel Family • Something Interesting in L4 μkernel • Introduction of The Platform • The Bug of USB Host Device Driver • Other Experiences of Driver Debugging

  3. Outline • Introduction of μkernel • Introduction of L4 μkernel Family • Something Interesting in L4 μkernel • Introduction of The Platform • The Bug of USB Host Device Driver • Other Experiences of Driver Debugging

  4. Monolithic Kernel • Kernel has access to all things • All optimizations possible • All techniques/mechanisms implementable • Kernel can be extended • To add more code to the kernel

  5. Why Microkernel(μkernel) • Cost of monolithic kernel • Complexity • Growing size • Limited maintainability

  6. The Idea of Microkernel • Provide core functionality • Applications communicate via message-passing IPC

  7. Outline • Introduction of μkernel • Introduction of L4 μkernel Family • Something Interesting in L4 μkernel • Introduction of The Platform • The Bug of USB Host Device Driver • Other Experiences of Driver Debugging

  8. History of Microkernel • 1st generation μkernel • Mach • Chorus • Amoeba • L3

  9. History of Microkernel (cont.) • 2nd generation μkernel • Spin (University of Washington) • Exo-kernel (MIT) • L4

  10. Comparison • 1st generation μkernel were slow • Complex API • Poor design and implementation • Too many features • Slow and inflexible IPC

  11. L4 Microkernel Family • A family of second-generation microkernel • There have been various re-implementations of the original L4 kernel interface(ABI) • Original version by JochenLiedtke

  12. Introduction of L4 Microkernel • The L4 kernel API has evolved in numerous ways • Version 2 • Version X.0 • Version X.2 • NICTA N

  13. Design Issue of L4 • Abstractions • Address spaces • Threads • Mechanisms • Inter-process communication (IPC) • Mapping

  14. Outline • Introduction of μkernel • Introduction of L4 μkernel Family • Something Interesting in L4 μkernel • Introduction of The Platform • The Bug of USB Host Device Driver • Other Experiences of Driver Debugging

  15. Famous L4 μkernel • Fiasco • Design by TU Dresden • Preemptible real-time kernel • Used for DROPS project • GPL License Last release: March 2007, Fiasco 1.2 http://os.inf.tu-dresden.de/drops/

  16. DROPS • Dresden Real-Time Operating Systems Project • Find design techniques for the construction of distributed real time operating systems • Every component guarantees a certain level of service to applications.

  17. DROPS (cont.) • Multiple instances of Linux running on one machine

  18. Famous L4 μkernel (cont.) • L4Ka::Pistachio • Design by L4Ka team and NICTA EROPS Group • L4 API V X.2 Last release: June 2004, Pistachio 0.4 http://l4ka.org/projects/pistachio/

  19. Famous L4 μkernel (cont.) • NICTA::Pistachio-embedded • Design by UNSW and NICTA EROPS Group • based on L4Ka::Pistachio, designed for embedded systems • keep almost all system calls short Last release: Feb 2007, pistachio 1.1 (discontinued) http://ertos.nicta.com.au/software/kenge/pistachio/latest/

  20. Famous L4 μkernel (cont.) • OKL4 • Design by OKLab (Open Kernel Labs) • OKLab spun out from NICTA • Based on NICTA::Pistachio-embedded • Commercial deployment Last release: Apr 2008, OKL4 2.1 http://wiki.ok-labs.com/

  21. OKL4 • Adopted by Qualcomm for CDMA chipsets • OKL4-based Toshiba phone http://www.fluffyspider.com/demos/live_videos/flv/fancypants-openmoko-neo1973-video-browser-phone-dialer.html

  22. Trusted Computing Base in μkernel traditional embedded Linux/ Windows Microkernel based System TCB all code 100,000’s loc 10,000’s loc Diagram from Kashin Lin (NEWS Lab)

  23. Related Research - SIGMA A Study on Asymmetric Operating Systems on Symmetric Multiprocessors, Yu Murata, Wataru Kanda, Kensuke Hanaoka, and Tatsuo Nakajima, EUC07 • Achieve asymmetric multiple operating system environments for symmetric multiprocessors • No virtualization • Direct control

  24. SIGMA (cont.) • A multiple OS environment • Host OS: L4 micro kernel (NICTA::L4-embedded) • Guest OS: SIGMA Linux • The OS manager • The bootloader of CPU1

  25. SIGMA (cont.)

  26. SIGMA (cont.) • Estimated use cases

  27. Outline • Introduction of μkernel • Introduction of L4 μkernel Family • Something Interesting in L4 μkernel • Introduction of The Platform • The Bug of USB Host Device Driver • Other Experiences of Driver Debugging

  28. Outline • Introduction of μkernel • Introduction of L4 μkernel Family • Something Interesting in L4 μkernel • Introduction of The Platform • The Bug of USB Host Device Driver • Other Experiences of Driver Debugging

  29. Outline • Introduction of μkernel • Introduction of L4 μkernel Family • Something Interesting in L4 μkernel • Introduction of The Platform • The Bug of USB Host Device Driver • Other Experiences of Driver Debugging

  30. GPIO

  31. GPIO support in DM6446 • 71 GPIO signals. • GPIO[53:0] are 1.8V I/O signals. • GPIOV33_[16:0] are 3.3V I/O signals. • 16 registers one bank • Total 5 banks

  32. Configure GPIO Registers

  33. Remarks in GPIO • Others important setting depend on the platform • Power • Pinmux

  34. Power Setting • In the DM644x system, the Power & Sleep Controller (PSC) is responsible for managing transitions of system power on/off, clock on/off, and reset

  35. Power Setting (cont.)

  36. Pinmux Setting • DM644x allows multiplexing of shared device pins between peripherals. • Check the GPIO pins you used whether shares to other device?

  37. Pinmux Setting (cont.)

  38. Pinmux Setting (cont.)

  39. Debug Experience

  40. SPI – DAC 88347 • Need a power meter • Send different value • Measure the voltage on output pin

  41. SPI – Input/Ouput Connection • DM6446 is master • Peripheral is slave • The SPI output pin of master device needs to be connected to the input pin of slave device.

  42. USB – Mode Setting • USB controller in DM6446 • Support USB 2.0 peripheral at High Speed (480 Mbps) and Full Speed (12 Mbps). • Support USB 2.0 host at High Speed (480 Mbps), Full Speed (12 Mbps), and Low Speed (1.5 Mbps).

  43. USB – Mode Setting (cont.) • USB_ID pin

  44. Thanks

  45. Q & A

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