panic: page fault in kernel (3B1/3.51m)

[Thad P Floryan]

alex at umbc3.UMBC.EDU (Alex S. Crain) in <4832 at umbc3.UMBC.EDU> writes:

	There is an alternate shared memory drive called lipc that you can use
	instead. I don't remember the details of the problems, but I remember
	reading something like: "nipc has some problems, but lipc isn't well
	tested, so try nipc first and use the other if it breaks."

	I can't for the life of me remember where I saw this, sorry. 

	Loaded drivers are more suseptible to paging problems then the regualr
	kernel, but I've never been able to figure out exactly what the
	difference is.

	In any case, try switching over to lipc. To do this, edit
	/etc/lddrv/drivers and reboot. Good luck.

Actually, "lipc" is the standard one and "nipc" is the optional, enhanced one.

On page 4 of "Important Information for Users of UNIX PC 3.51 Software" (a
loose supplement to the 3.51 docs) is found (page numbers refer to AT&T UNIX
PC Owner's Manual):

``	Page 4-26.  There are two IPC drivers listed in the Loadable Device
	Driver Interface window:

		Standard Sys V IPC (lipc)

			and

		Enhanced Sys V IPC (nipc)

	The standard IPC driver will be loaded by default and should remain
	so under most circumstances. The enhanced IPC driver is a noncertified
	version containing fixes for specific system problems.  If when running
	a particular software package you receive a system message indicating:

		kernel crash: rmfree panic

	you should unload the standard IPC driver and load the enhanced IPC
	driver.  Follow the directions in the Owner's Manual.
''

and looking at the drivers (this is ONE of the reasons I wrote "coffdate"
which I recently posted):

	thadlabs ksh 24989/24990> cd /etc/lddrv
	thadlabs ksh 24989/24990> ls -l lipc* nipc*
	-rwxrwxrwx  1 root    root      34127 Oct 13 23:54 lipc
	-rw-r--r--  1 bin     bin       18628 Jan  1  1970 lipc.o
	-rw-r--r--  1 bin     bin       20752 Jan  1  1970 nipc.o
	thadlabs ksh 24989/24990> coffdate lipc* nipc*
	Sat Oct 13 23:54:32 1990  lipc
	Sat Apr 18 15:36:05 1987  lipc.o
	Sat Apr 18 15:37:55 1987  nipc.o

I really do NOT believe the problem is related to nipc because I just found
the following (but NOTE the WARNING (this is from the guy who "did" 3.51m)):

+ Relay-Version: version B 2.10.3 4.3bsd-beta 6/6/85; site portal.UUcp
+ Path: portal!uunet!ginosko!xanth!ames!apple!sun-barr!rutgers!att!andante!\
+   ulysses!dptg!mtunb!jcm
+ From: jcm at mtunb.ATT.COM (was-John McMillan)
+ Newsgroups: unix-pc.general
+ Subject: lipc  vs  nipc -- and 'ipcs'
+ Message-ID: <1567 at mtunb.ATT.COM>
+ Date: 18 Jul 89 20:00:56 GMT
+ Date-Received: 19 Jul 89 11:21:49 GMT
+ Reply-To: jcm at mtunb.UUCP (John McMillan)
+ Organization: AT&T ISL Middletown NJ USA
+ Lines: 38
+ Keywords: lipc nipc ipcs
+ Summary: 'ipcs' only knows of 'lipc'
+ Portal-Origin: Usenet
+ Portal-Type: text
+ Portal-Location: 5262.3.1470.1
+ 
+ If you do not use Inter-Process Communication features --
+ 	specifically, if you do not use 'nipc' instead of 'lipc' --
+ 	then ignore the following.
+ 
+ 			- - - - - - - - - - - -
+ 			This is a minor warning:
+ 
+ Many moons ago, as CT was terminating their work and a new release was
+ 	being finalized, an IPC bug was fixed -- but CT would not
+ 	accept the 'fix' because there was inadequate time/resources
+ 	to validate it to their satisfaction.  The loadable driver
+ 	'lipc.o' -- their package -- was retained and the new version was
+ 	added to the /etc/lddrv directory as 'nipc.o'.
+ 
+ Those users who reported an error message of something like "rmfree error"
+ 	were instructed to switch to using 'nipc'.  If this switch
+ 	was made by REPLACING 'lipc.o' with 'nipc.o', no problem
+ 	arises.
+ 
+ However, if the user changed the 'drivers' file such that 'nipc' was
+ 	specified as the driver to use -- rather than 'lipc' -- the
+ 	program 'ipcs' cannot find the correct information as it
+ 	has no information about 'nipc'.  IPC works just fine, but
+ 	the report-program indicates IPC is not implemented.
+ 
+ 			- - - - - - - - - - - -
+ 			REQUEST FOR INFORMATION
+ 			- - - - - - - - - - - -
+ 
+ In the two intervening years, not a single 'nipc' bug has been
+ 	reported (to me).  IF YOU USE *NIPC* and have observed
+ 	any bugs, please E-MAIL me any details:
+ 
+ 			att!mtunb!jcm
+ 
+ Otherwise, I am inclined to replace lipc with nipc in the fix disk.
+ 
+ john mcmillan	-- att!mtunb!jcm


Thad Floryan [ thad at cup.portal.com ]