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• In our case, the boot code starts at startup
  • Other names are start, download_entry and __rtems_entry_point
• Boot code vaguely follows the "Initialization Software Requirements" outlined in the PowerPPC 440x5 Embedded Processor Core User's Manual v7.1 from IBM
  • Why only "vaguely"?
• Clear MSR
• Disable debug events
• Configure instruction and data cache registers
• Set up decrementer and timer registers
• Clear exception registers ECR and XER
• Invalidate instruction and data caches
• Clear the CPU reservation bit
• Set up CCR0, CCR1, MMUCR, CRF and CTR
• Set up TLB pages
• Set up debug events
• Set up EABI and SYSV environment
• Clear out BSS section
• Load vector offset register
• Set up TOC ( overwrites r2?)
• Set up initial stack
• Set up argument registers r3, r4 and r5
• Branch to boot_card()

boot_card()

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While the RTEMS structure provides for allowing this function to be supplied by the RTEMS BSP, we use the version that the distribution comes with. It is found in the $RTEMS_ROOT/src/c/src/lib/libbsp/shared directory called bootcard.c.

In the following, functions prefixed with bsp_ are supplied by the RTEMS BSP.

• Command line is in first argument
  • In our system this is always a null pointer
• Disable interrupts
• Store command line
• Call bsp_start()
• Determine RTEMS work area and heap location and size
• Initialize RTEMS data structures
• Initialize the C library
  • This also installs the heap
• Call bsp_pretasking_hook()

• Wiki Markup
  \[Enable RTEMS debugging capabilities\]

• RTEMS initialization before loading device drivers
• Call bsp_predriver_hook()
• Initialize device drivers
• Call bsp_postdriver_hook()
• Start multitasking
  • Thread with entry point Init runs
  • Not clear how this returns. Perhaps when the last task is deleted?
• Call bsp_cleanup()
• Return to start code
  • Not clear what's in the lr at this point, i.e., where do we return to?

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