What is vmunix/genvmunix? What alternatives for b/3?

[Alan's Home for Wayward Notes File.]

In article <74094 at bu.edu.bu.edu>, jdubb at bucsf.bu.edu (jay dubb) writes:
> 
>    I am posting this for a friend of mine who doesn't have access
> to USENET, so please respond directly to mlevin at jade.tufts.edu.

	I'll follow-up and reply to the sender.  Once again this
	is probably of general interest.
> 
>    What is vmunix and genvmunix (and the difference between them)?
> Also, what are the alternatives for the argument to the b/3 (boot)
> command from the >>> prompt?

	genvmunix is a generic kernel that we ship with the base
	system.  It has drivers and data structures for nearly 
	everything supported, but the proverbial kitchen sink,
	built into it.  About the only thing I know of that isn't
	included are UDA50 and KDA50 controllers in floating	
	address space and assorted communications devices like
	DZs, DMFs, DHU, etc that are in predictable locations.  
	It is used as the running kernel during the installation 
	process and by doconfig(8) to build a system specific 
	configuration.

	vmunix is the ULTRIX kernel itself.  Unless the local
	configuration file has been modified and the kernel
	rebuilt, it has only those drivers and devices that
	are on the system.

	Other interesting differences:

	   o  The GENERIC kernel is a single processor system.  No
	      SMP support is included.

	   o  The generic kernel assumes that the root file system
	      is on the A partition of the boot device and that the
	      ONLY page/swap partition is on the B partition of that
	      device.

	   o  MAXUSERS is set to 2.  This seriously limits some of the
	      kernel table sizes.

	   o  Only 10 processes are allowed for those two users.

	   o  It assumes the system is in the U.S. Eastern timezone
	      and that the rules for Daylight Savings Time are in
	      affect.

	   o  There are 6 MB of physical memory.  I don't think this
	      really has much affect, since the usual check made on
	      physical only cares about the value being greater than
	      64 MB or not.

	   o  The size of the buffer cache is limited by MAXUSERS.

	   o  DECnet and DLI support aren't included, but NFS and
	      RPC support are.
	
> 
> 			Mike Levin (mlevin at jade.tufts.edu)


-- 
Alan Rollow				alan at nabeth.cxn.dec.com