Subject: Re: Making UFS optional
To: Wolfgang Solfrank <>
From: Jan-Simon Pendry <>
List: tech-kern
Date: 03/04/1994 08:32:02
	In an attempt to stir up some more user complaints of the type
	"my kernel doesn't build any more" :-), I'm going to make ufs
	(more or less) optional.

well, if it's not totally optional, then it's not optional,
but perhaps it should be done.  do people really want diskless
systems these days?

	This means, moving quite some code out of the ufs directory.


	There are parts in there that obviously have to go into the
	vfs code and thus are moved into the kern directory.

	Then there are the iftovt_tab & vttoif_tab tables, that are
	used (due to semantic extension of the nfs protocol) by nfs,
	too. This will go into a separate file in the ufs directory
	and be made optional on ufs or nfsserver.

in 4.4, these are already in kern/vfs_subr.c.

	And then there is the file ufs_disksubr.c, which hasn't anything
	to do with ufs at all. It contains code that is used by most
	(if not all) disk drivers.  I'm not sure where to place this

	Should it go into the kern directory and made optional on all
	the disk drivers (needs inclusion of this file in all the
	machine dependent configuration files and editing
	this files in non-obvious places, when a new driver is added),
	made standard (superfluous inclusion of code for diskless
	machines) or placed into libkern (my preference, but up until
	now libkern only includes routines that (re-)implement things
	that are also available in user mode.

this should probably be kern/kern_disksubr.c, or else put it in
libkern.  (if you're really bored, there are a ton of other things
which should also go into libkern, eg the vttoif tables.)  i don't
think there's any point making it "optional".  it is used by 95% of
systems, and on those where it isn't, you're wasting less then 2K of
text space.  if you're desperate to save the 2K, put it in libkern.

	Any ideas?

wait for 4.4-lite before doing code re-orgs.