Alternate Boot Images and Safe Start

Chapter 3 MOTLoad Firmware

Some later versions of MOTLoad support Alternate Boot Images and a Safe Start recovery procedure. If Safe Start is available on the MVME6100, 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 MCG boot image; anticipated to be upgrade of MCG 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 MCG 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.

Firmware Scan for Boot Image

The scan is performed by examining each 1MB boundary for a defined set of flags that identify the image as being Power On Self Test (POST), USER, or MCG. MOTLoad is an MCG image. POST is a user-developed Power On Self Test that would perform a set of diagnostics and then return to the bootloader image. User would be a boot image, such as the VxWorks bootrom, which would perform board initialization. A bootable VxWorks kernel would also be a USER image. Boot images are not restricted to being MB or less in size; however, they must begin on a 1MB boundary within the 8MB of the scanned flash bank. The Flash Bank Structure is shown below:

MVME6100 Installation and Use (V6100A/IH2)