[SunRescue] TOD Clock Bit Error -- Autobooting at Last!

[rescue at sunhelp.org]

Ok NVRAM replacement chip fans.  Let's review:

1) In June, 2000 ST Microelectronics changed the operation of =

   the M48T02/MT48T12 "Timekeeper" NVRAM chip that older Sun =

   boxes use.  The new version requires strict adherence to the
   chip specification, the older version does not.  Sun PROM =

   apparently does not initialize the chip properly, per the =

   spec so newer chips will report an error on startup:

   FAILURE: TOD (f20007fa) Bit Failure, Exp =3D 000000ff, Obs =3D 0000007=
f

2) The error is independent of NVRAM chip speed.  Faster chips =

   that worked appeared to be pre-June 2000 manufacture.

3) Once initialized, the new chip works fine.  But since the =

   Sun thinks the chip is bad, it apparently halts the =

   oscillator, so powering down and shutting off a Sun box with
   the new chip will freeze the date/time at the time of power
   off.  Just rebooting the machine apparently does not effect
   the clock.

4) The most annoying issue is that the machine will not =

   autoboot because it reports a problem witht he NVRAM chip.

Well, I can do anything about numbers 1 through 3, but I DO =

have an answer to the autoboot problem!  You need to implement
an nvramrc command set.  One of the problems with using =

nvramrc is that it gets run BEFORE any devices are defined
in the boot sequence.  So, your nvramrc commands must call
each PROM routine to identify the devices, install the console
device and trigger the boot process.  The sequence that I'm =

using is:

           probe-all
           install-console
           banner
           boot

It looks kind of trivial, but it works!  To establish the =

nvramrc, you have to get to the PROM's OK prompt.

Run the "nvedit" command to create the nvramrc file.  It
will prompt you line by line.  Enter the four lines above.
When it prompts you for the 5th line, type a Control-C
to get back to an OK prompt.  Enter the "nvsave" command.

Next, set the use-nvramrc? variable to "true".  At the OK
prompt:

          setenv use-nvramrc? true

Now issue a "reset" and you're autobooting!
 =


___________________________________________________________________ =

---- Harry J. Regan
---- Phone: 202.310.2719
---- FAX:   212.202.3923
---- harry.regan at usa.net =




____________________________________________________________________
Get free email and a permanent address at http://www.amexmail.com/?A=3D1