Technical data

MVME3100 Single Board Computer Installation and Use (6806800G36A)
MOTLoad Firmware Alternate Boot Images and Safe Start
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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.
3.10.6 Boot Image Firmware Scan
The scan is performed by examining each 1 MB boundary for a defined set of flags that identify
the image as being POST, USER, or Alternate MOTLoad. POST is a user-developed Power On
Self Test that would perform a set of diagnostics and then return to the boot loader 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 1 MB or less in size; however, they must begin on a 1 MB boundary within
the 8 MB of the scanned flash bank. The flash bank structure is shown below:
The scan is performed downwards beginning at the location of the first possible alternate image
and searches first for POST, then USER, and finally Alternate MOTLoad images. In the case of
multiple images of the same type, control is passed to the first image encountered in the scan.
Safe Start, whether invoked by hitting ESC on the console within the first five seconds following
power-on reset or by setting the Safe Start jumper, interrupts the scan process. The user may
then display the available boot images and select the desired image. The feature is provided to
enable recovery in cases when the programmed Alternate Boot Image is no longer desired. The
following output is an example of an interactive Safe Start:
ABCDEInteractive Boot Mode Entered
boot> ?
Interactive boot commands:
'd':show directory of alternate boot images
'c':continue with normal startup
'q':quit without executing any alternate boot image
'r [address]':execute specified (or default) alternate image
'p [address]':execute specified (or default) POST image
'?':this help screen
'h':this help screen
boot> d
Addr FFE00000 Size 00100000 Flags 00000003 Name: MOTLoad
Addr FFD00000 Size 00100000 Flags 00000003 Name: MOTLoad
boot> c
Address Usage
0xFFF00000 to 0xFFFFFFFF Boot block. Recovery code.
0xFFE00000 to 0XFFFFFFFF Backup MOTLoad image
0xFFD00000 to 0xFFDFFFFF First possible alternate image
0xFFC00000 to 0xFFCFFFFF Second possible alternate image
.... Alternate boot images
0xFF899999 to 0xFF8FFFFF Bottom of flash (flash size varies per product)