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                                 MEMORANDUM
  
  TO:     Jim Belcher
  
  FROM:   Keith Corbett
  
  DATE:   July 18, 1986

  SUBJ:   /sys Directory
  
  COPY:   John Salis, Ron Rando, Steve Zeogas

    
  MCC (Human Interface) has requested that we supply them with the
  System 5 /sys directory.  MCC wants the capability to create
  their own custom software device drivers on both the Lambda and
  68010.
  
  To assist them, LMI has agreed to provide /sys (plus the Lambda
  document "Multibus Driver Guide"), provided that they accept
  certain obligations on their part regarding maintenance on their
  system(s) where they are writing custom drivers.
  
  BENEFITS
  --------
  
  One of the main reasons MCC/HI bought the Lambda system (MCC
  #25, serial #9012) is the ability to add a board to the Multibus
  and access it from both Lisp and Unix.  Without /sys, they will
  not be able to work on their project.
  
  Also, /sys is provided by other vendors of Unix.  However, they
  are true "Unix shops", with extensive resources for supporting
  Unix systems.  LMI, unfortunately, is not in a position to do
  this comfortably.
  
  RISKS
  -----
  
  The /sys directory under System 5 contains object modules which
  can be linked with the kernel program. The kernel is the master
  program which controls the resources of the machine.  With this
  /sys directory, users can make modifications to the kernel, thus
  changing the behavior of their system.
  
  Hear are some problems that could be caused by their own device
  drivers:


        A) They can conceivably destroy all information on the
           disk(s) or corrupt other devices.

        B) If machine is on the network, can possibly affect
           other machines and/or corrupt the network.

        C) They can provoke bugs in Unix which could be
           impossible for LMI to correct given our resources.
           It could be difficult to distinguish between bugs
           created by the modifications to the kernel as
           opposed to the rest of system.

        E) They can render their system incompatible with future
           releases of system software or hardware.

  Resolution
  ----------
  
  We suggest that LMI supply /sys with the following
  provisions:

        A) If MCC's machines becomes unstable or unbootable due  
           to modifications to the kernel program, then they must
           reload our released software before any corrective action
           can occur.  If their disk needs to reformatted, a service
           call is required.

        B) MCC will reload standard system software when upgrading to
           new releases of LMI software, and certify acceptance
           of same before loading their own drivers.

        B) LMI will not support any new functionality created
           by modifications to the kernel program.

    
  A letter or agreement accompanying the tape should go over
  these points and contain the following disclaimer, or
  equivalent:

                           DISCLAIMER

        LMI assumes no responsibility for any modifications made
        to Unix System 5 or the LISP environment.  LMI will not 
        support such changes to the Kernel program or to any
        other supplied program.

        Extreme caution must to exercised, since a modified kernel
        program may render the system unstable or unbootable. If
        changes are made and as a result problems do occur, LMI can
        only recommend reloading all the original standard software
        provided.  This action is also required as a pre-
        requisite to any scheduled or corrective maintenance.  

        We also suggest that consistent up-to-date backups be
        maintained before any changes are made to the system.
          
  Can you please follow up with a letter or agreement that will
  protect LMI and still enable us to give /sys to MCC?



  KMC