Help running 2.11 on Supnik 2.3d

Steven M. Schultz sms at
Thu Apr 13 13:22:56 AEST 2000

Hi --

> From: lars brinkhoff <lars at>
> I've tried running the image in /Boot_Images/2.11_on_rl02 on
> Supnik's emulator version 2.3d, but the root filsystem seems
> corrupted, with many binaries being unexecutable, bad block error messages, 
> etc.
> Does anyone know how to successfully boot this image?

	Yes.  The problem is not with the images (although the whole "on rl02"
	is a pain - you're far better off using the "xp" or large disk support
	that Bob added).

> If this is the wrong place for this kind of question, or if
> there's a FAQ on this, then please point me in the right direction.

	This is a very good place to ask this type of question.

	And now the moment you've been waiting for:  "the Answer" ;)

	2.11BSD is *very* upset at having to run in 256kb of memory.  since
	the kernel plus buffer cache (and other data structures) can easily
	exceed 200kb there is not enough memory left over to run a program.
	Programs such as 'fsck' are fairly large split I/D programs and won't
	fit in the remaining ~56kb or so.

	The quick fix to the problem is adding the line:

		set cpu 2048K

	to the config file before running the simulator.  That will give the
	simulated PDP-11 2Mb of memory which is a real nice size.  Oh, if
	memory is a concern on the system then "set cpu 1024K" will work
	well.  Since there's no networking involved 1Mb will be quite adequate.
	If you were using "P11" (the Begemot emulator) and had the full IP/TCP
	stack, etc then the kernel+networking+buffers can reach close to 400Kb
	and you might want to use 2Mb for the memory size.

	You might also look into the latest version (2.5) of the Begemot
	emulator.  The two key advantages of P11 are:  1) a emulated DEQNA so
	you can place the PDP11 on a network, 2) It keeps _good_ time
	(version 2.4 and earlier had severe timeskew when running compute
	bound programs, 2.5 is awesomely better and within range of "ntp"
	to keep the clock correct).  P11 also supports (as does Bob Supnik's
	simulator) large disks such as the RP06 which is much nicer than
	4 RL02s and a batch of RK05s.

	Hmmm, I'm not sure which rev level of 2.11BSD is in the "on_rl02"
	images - I hope it has the "bounce buffer support" to handle the 18bit
	RK controller on a 22bit bus...   If the RK images show corrupt or the
	kernel crashes then I would suspect the kernel is a bit too old.

	Unpack the "211bsd_on_rl02" images from the .gz images, edit the
	"script" file to increase the system memory and you should be all
	set to go.


Received: (from major at localhost)
	by (8.9.3/8.9.3) id OAA94566
	for pups-liszt; Thu, 13 Apr 2000 14:56:35 +1000 (EST)

More information about the TUHS mailing list