Chapter 3 MOTLoad Firmware
Alternate Boot Images and Safe Start
Some later versions of MOTLoad support Alternate Boot Images and a Safe Start recovery procedure. If Safe Start is available on the MVME3100, Alternate Boot Images are supported. With Alternate Boot Image support, the bootloader code in the boot block examines the upper 8MB of the flash bank for Alternate Boot images. If an image is found, control is passed to the image.
Firmware Startup Sequence Following Reset
The firmware startup sequence following reset of MOTLoad is to:
■Initialize cache, MMU, FPU, and other CPU internal items
■Initialize the memory controller
■Search the active flash bank, possibly interactively, for a valid POST image. If found, the POST images executes. Once completed, the POST image returns and startup continues.
■Search the active flash bank, possibly interactively, for a valid USER boot image. If found, the USER boot image executes. A return to the boot block code is not anticipated.
■If a valid USER boot image is not found, search the active flash bank, possibly interactively, for a valid Alternate MOTLoad boot image; anticipated to be an upgrade of Alternate MOTLoad firmware. If found, the image is executed. A return to the boot block code is not anticipated.
■Execute the recovery image of the firmware in the boot block if no valid USER or alternate MOTLoad image is found
During startup, interactive mode may be entered by either setting the Safe Start jumper/switch or by sending an <ESC> to the console serial port within five seconds of the board reset. During interactive mode, the user has the option to display locations at which valid boot images were discovered, specify which discovered image is to be executed, or specify that the recovery image in the boot block of the active Flash bank is to be executed.
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