cant start 9pcfs

[Paul Borman prb@bsdi.com]

> >>This is most certainly due to a memory sizing problem (heaven knows
> >>we have made the rounds with this one with BSD/OS...)  For now I
> 
> are the bytes in the CMOS that give the extended memory size not standard,
> or do some machines not set them correctly?

Well, we have found that many (all?) Dell machines think that the CMOS
can never report more than 16MB, so it doesn't, even if you have more
than 16MB of memory.  Then there are machines which we can't accurately
probe for how much memory there is, but the CMOS is right!  There are
also weird caching affect (i.e. you can read/write memory beyond the
end of memory as long as it stays in cache) as well as new and unique
ways to remap addresses that are beyond the end of memory.  To give you
and idea, here are the various parameters one can set in their boot.default
file for BSD/OS:

	-basemen mem	Assume this much base memory (memory below 1M)
	-cmosmem	Limit memory search to the mount given by the CMOS
	-extended mem	Limit the amount of memory to check
	-memsize mem	Just assume this it the amount of memory
	-noflushcache	Don't flush the cache while sizing memory

Each one of these is needed for at least one machine that we have had
problems with.  I should note that we can probe the proper amount of
memory on *most* machines, but...

Finding out how much memory you have is certainly a black art.

				-Paul Borman
				 prb@bsdi.com