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MOTLoad Firmware
MVME3100 Single Board Computer Installation and Use (6806800M28C)
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3.10.4 Alternate Boot Data Structure
The globalData field of the alternate boot data structure points to an area of RAM which was
initialized to zeroes by the boot loader. This area of RAM is not cleared by the boot loader after
execution of a POST image, or other alternate boot image, is executed. It is intended to provide
a user a mechanism to pass POST image results to subsequent boot images.
The boot loader performs no other initialization of the board than that specified prior to the
transfer of control to either a POST, USER, or MCG image. Alternate boot images need to
initialize the board to whatever state the image may further require for its execution.
POST images are expected, but not required, to return to the boot loader. Upon return, the
boot loader proceeds with the scan for an executable alternate boot image. POST images that
return control to the boot loader must ensure that upon return, the state of the board is
consistent with the state that the board was in at POST entry. USER images should not return
control to the boot loader.
3.10.5 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 boot loader code in the boot block examines the upper
8 MB of the flash bank for alternate boot images. If an image is found, control is passed to the
image.