Board Bringup

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Board Bringup

  1. 1. Board Bringup © 2010 Anil Kumar Pugalia <email@sarika-pugs.com> All Rights Reserved.
  2. 2. What to Expect? Board specific Details Understanding the target board How to play with the target board? Peeking into Vendor supplied Utilities, if any © 2010 Anil Kumar Pugalia <email@sarika-pugs.com> 2 All Rights Reserved.
  3. 3. Startup Doubts Typical doubts you may have, be it your desktop or board What happens when you switch on the power? Where does the processor starts executing on “Power on Reset”? What code is there? Do you have access to that code? How does the Operating System boot up? How does the login prompt come? Any many more © 2010 Anil Kumar Pugalia <email@sarika-pugs.com> 3 All Rights Reserved.
  4. 4. Startup Sequence To Decode all these, let's understand the Startup Sequence Processor / Controller Startup Bootloader or the Software Startup Operating System Startup Application Startup Though they may vary from board to board, we can have a generic overview And then, we shall get into your board specifics © 2010 Anil Kumar Pugalia <email@sarika-pugs.com> 4 All Rights Reserved.
  5. 5. Processor / Controller Startup Controller Internal Code Mostly exists in Controllers (Embedded Systems) System Startup / Setup Code Mostly exists for Processors in Desktops Processors jump to a pre-designated address, typically Zero, to run these pre-programmed code Referred as BIOS in the Desktop parlance Needs to be programmed once, on virgin boards In both the cases, the Code looks for the Stage1 Bootloader at the designated places Embedded: EEPROM, Flash, Serial Download, … Desktops: Floppy, CDROM, Hard Disk, Network, ... © 2010 Anil Kumar Pugalia <email@sarika-pugs.com> 5 All Rights Reserved.
  6. 6. Software Startup Stage 1 Bootloader Initial Program Loader (IPL) in Embedded World Master Boot Record (MBR) in Desktops Constrained to limited Space. Can't do much So, loads Stage 2 Bootloader Have enough space to do luxurious stuff Provides configurability and management features Loads the Operating System Passes arguments to the Operating System Jumps to start executing the Operating System For Desktops: LILO, GRUB, SYSLINUX, ... In Embedded Systems: u-boot and others Also called Secondary Program Loader (SPL) © 2010 Anil Kumar Pugalia <email@sarika-pugs.com> 6 All Rights Reserved.
  7. 7. Operating System Startup Uncompresses the kernel, if compressed Configures itself based on the arguments from the Stage 2 Bootloader Setup the Kernel Space Jump execution to the first application “init” Common to both Desktop & Embedded © 2010 Anil Kumar Pugalia <email@sarika-pugs.com> 7 All Rights Reserved.
  8. 8. Application Startup init This could be the application binary itself. Or, Could be a link to it It typically starts the various daemons And then does things as per the system's requirement In Desktop, starts the login process to provide login prompts In Embedded Systems, does the same at least during Development Cycle Later, may do specific to customer requirement © 2010 Anil Kumar Pugalia <email@sarika-pugs.com> 8 All Rights Reserved.
  9. 9. Startup Sequence Power Up / Reset BIOS System Startup Controller Code Master Boot Record Stage 1 Bootloader Initial Program Loader LILO, GRUB, … Stage 2 Bootloader u-boot, ... Operating System Linux Kernel Operational Application init → busbox, ... © 2010 Anil Kumar Pugalia <email@sarika-pugs.com> 9 All Rights Reserved.
  10. 10. Let's Startup the Board © 2010 Anil Kumar Pugalia <email@sarika-pugs.com> 10 All Rights Reserved.
  11. 11. Anatomy of Development Board Being a Embedded Developer, you should know your board in more detail Both Hardware Major components Types of memories Software Manufactured State Factory Restoration © 2010 Anil Kumar Pugalia <email@sarika-pugs.com> 11 All Rights Reserved.
  12. 12. Let's Browse the Board © 2010 Anil Kumar Pugalia <email@sarika-pugs.com> 12 All Rights Reserved.
  13. 13. Manufactured State State at which, it was when manufactured Also called the Virgin State Achieved by erasing all the memories EEPROM Flash – NOR, NAND, ... This, in principle erases Bootloaders – Stage 1 & Stage 2 Kernel File Systems © 2010 Anil Kumar Pugalia <email@sarika-pugs.com> 13 All Rights Reserved.
  14. 14. Factory Restoration So, this is to get the Board back to boot up In principle, populating back the memories erased with Stage 1 & Stage 2 Bootloaders Kernel Root File System Optionally, the Other File Systems Would need some special utilities Provided by the board vendor (the factory guy) Examples: RAM Monitor, Boot Monitor, ... At times of nothing, these are good debug utilities, as well © 2010 Anil Kumar Pugalia <email@sarika-pugs.com> 14 All Rights Reserved.
  15. 15. What all have we done? Understood the target board Switching it on Accessing the stuff on it Configuring it How to play with the target board? Decoding the Hardware Taking it to a virgin state Restoring it to factory defaults © 2010 Anil Kumar Pugalia <email@sarika-pugs.com> 15 All Rights Reserved.
  16. 16. Any Queries? © 2010 Anil Kumar Pugalia <email@sarika-pugs.com> 16 All Rights Reserved.

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