MVME162_overwrite_bootup_params.html

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Overwrite bootup parameter(s) on MVME using debug mode

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MVME162

MVME power pc

Introduction

When a ram disk is installed, the MVME board can get in a state where it is impossible to get the consol prompt back after a reboot. It is not possible to break in to the startup procedure by pressing a key on the consol keyboard (the normal procedure). Usually this happens when there is an error in startup file. In this case, the way to recover is to overwrite the startup file name in ram with blanks. Then no startup procedure will be executed.

For this reason, when testing new code or startup files with a ram disk in place, it is very prudent to temporarily set the bootup parameter "startup script" blank, so that no automatic startup file will be loaded.

MVME162: To overwrite startup parameter(s) using 162-bug

MVME162: Boot board into 162-bug

Boot up the debugger , 162-bug.

Type "he" for help on the debugger.
162-Bug> md fffc0000:100;B     (memory display in Bytes)

This will display the startup parameters in memory. Look carefully for where the startup file name is stored. You should see a string e.g. "s=/ram/stcamp.dev". Determine a suitable starting point for the mm command and modify the memory after the "s=" to be blank.

IMPORTANT - each case is different so you must use the dump to find the right place to overwrite. For example,

162-Bug> mm fffc005b;b   (memory modify in bytes)
     76?        carriage return (don't modify)
     77?
     73?
     30?
     2f? 00  <- write zero to overwrite the startup filename
     70? .   <- write . to exit from mm
162-Bug>

Boot VxWorks

Power down and replace the jumper to boot VxWorks. The VxWorks prompt should appear. To test a new startup file, load it by hand at first, using e.g.

-> < /vw/startup.file

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Power-PC: To overwrite startup parameter(s) using ppc-Bug

Boot board into ppc-Bug

Note - these instructions are just notes. Need checking.

Power off and switch jumper J15 (see ppc hardware manual)

J15
1-2 jumpered = Normal (VxWorks)
3-2 jumpered = ppcBug

Power up.

ppc-bug> gevshow      shows present parameters
ppc-bug> gevdump
             F94000 is start of bootup params
ppc-bug> gevinit  Initializes all params
  Update global environment area of NVRAM (y/N)?
               answer      Y

Power off and replace jumper.