[OpenBIOS] Latest SPARC64 & Milax update

Stefan Reinauer stepan at coresystems.de
Fri Jan 1 21:46:28 CET 2010

On 1/1/10 8:47 PM, Mark Cave-Ayland wrote:
> Mark Cave-Ayland wrote:
>> Stepping through with the debugger shows that it is now dying in the
>> very last line of exec-file which reads:
>> " to load-base init-program"  evaluate
>> So it looks as if we're very nearly there. My guess would be that
>> OpenBIOS is dying somewhere within init-program. Does anyone know
>> anything about what init-program should be doing under SPARC64? Has
>> it ever been tested before?
> Hmmmm now I see what the problem is - load-base is actually a special
> configuration word and not a variable. Hence when the Fcode executes
> "to load-base" it overwrites the first part of the load-base word
> causing the crash.
> Reading the OF specification in section it seems that OpenBIOS
> violates the Fundamental Data Type property of configuration variables
> since they are stored in a special configuration word format. I think
> the only way to solve this is rework the NVRAM code so that it
> respects the fundamental data types when creating the configuration
> variables. Does everyone agree that this is the way forward?
I don't think that's the right approach, because the code in Milax seems
to be what's not standard conform here. It relies on an implementation
specific detail of SUN's OFW.

IEEE 1275-1994 says:
> Thus, they cannot be accessed at fixed locations, but instead must be
accessed by name. Users can access them by name using printenv and setenv.

Note there is no mentioning of any specific data type for configuration
variables anywhere in Milax assumes that load-base is a value
(not a variable), hence the "to".

I suggest as a workaround for this particular bug in Milax to add
something like the following code at the end of nvram.fs:

>  load-base value load-base

This will leave the environment variable "load-base" intact for the use
in the standard conform way and create a shadow value that will be used
by Milax. This shadow value will be initialized with the initial value
of load-base.


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