The modified portion from original pintos, is subject to the following license:

    				 RECEX SHARED SOURCE LICENSE
    		 version 1.0, 30 May 2013

     Copyright (c) 2020 Casys lab, KAIST. <http://casys.kaist.ac.kr>
     Everyone is permitted to copy and distribute verbatim
     copies of this license document, but changing it is
     not allowed.

             TERMS AND CONDITIONS

      0. Definitions.

     "This License" refers to version 1.0 of RecEx Shared
     Source License.

     "The program", "the source", "the source code", "these
     files", "this file" refers to any copyrightable work
     licensed under this License.

     "You" refers to the Licensee. The licensee could be a
     person or a organisation.

     "personal use" refers to usage by, only and only, the
     licensee, and not by any other person or organisation
     related in any way to the licensee.

      1. Usage

     You are free to download, copy, compile, study, and
     refer to the source code for any personal use of yours.

     Usage by you of any work covered by this license should
     not, directly or indirectly, enable its usage by any
     other individual or organisation.

      2. Modifications

     You are free to make any modifications to the source
     covered by this license. You are also free to compile
     the source after modifying it and using the compiled
     product obtained thereafter in compliance with this
     License.

      3. Redistribution

     You may NOT under any circumstance copy, redistribute
     and/or republish the source or a work based on it (which
     includes binary or object code compiled from it) in part
     or whole.

      4. Non-compliance

     You may not copy, modify, sublicense, or distribute the
     Program except as expressly provided under this License.
     Any attempt otherwise to copy, modify, sublicense or
     distribute the Program is void, and will automatically
     terminate your rights under this License.

      5. Acceptance of License

     You are not required to accept this License, since you have
     not signed it. However, nothing else grants you permission
     to modify or use the source. These actions are prohibited
     by law if you do not accept this License. Therefore, by
     modifying or using the source (or any work based on the
     source), you indicate your acceptance of this License to do
     so, and all its terms and conditions for copying,
     redistributing or modifying the source or works based on it.

      6. Permissions

     If you intend to incorporate the source code, in part or whole,
     into any free or proprietary program, you need to explicitly
     write to the original author(s) to ask for permission.

      7. No Warranty

     The source code licensed under this license is shared "as is".
     Since it is intended for sharing as reference, there is no
     warranty, of either the source code, or the program compiled
     from it. The entire risk of quality or performance of the
     program is with you.

     THE ORIGINAL AUTHOR OF THE PROGRAM IS NOT LIABLE TO YOU FOR
     DAMAGES, INCLUDING ANY GENERAL, SPECIAL, INCIDENTAL OR
     CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OR INABILITY TO
     USE THE PROGRAM (INCLUDING BUT NOT LIMITED TO LOSS OF DATA OR
     DATA BEING RENDERED INACCURATE OR LOSSES SUSTAINED BY YOU OR
     THIRD PARTIES OR A FAILURE OF THE PROGRAM TO OPERATE WITH ANY
     OTHER PROGRAMS)

         END OF TERMS AND CONDITIONS

The original version of the Pintos, including its documentation, is subject to
the following license:

    Copyright (C) 2004, 2005, 2006 Board of Trustees, Leland Stanford
    Jr. University.  All rights reserved.

    Permission is hereby granted, free of charge, to any person obtaining
    a copy of this software and associated documentation files (the
    "Software"), to deal in the Software without restriction, including
    without limitation the rights to use, copy, modify, merge, publish,
    distribute, sublicense, and/or sell copies of the Software, and to
    permit persons to whom the Software is furnished to do so, subject to
    the following conditions:

    The above copyright notice and this permission notice shall be
    included in all copies or substantial portions of the Software.

    THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
    EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
    MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
    NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE
    LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION
    OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION
    WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

A few individual files in Pintos were originally derived from other
projects, but they have been extensively modified for use in Pintos.
The original code falls under the original license, and modifications
for Pintos are additionally covered by the Pintos license above.

In particular, code derived from Nachos is subject to the following
license:

/* Copyright (c) 1992-1996 The Regents of the University of California.
   All rights reserved.

   Permission to use, copy, modify, and distribute this software
   and its documentation for any purpose, without fee, and
   without written agreement is hereby granted, provided that the
   above copyright notice and the following two paragraphs appear
   in all copies of this software.

   IN NO EVENT SHALL THE UNIVERSITY OF CALIFORNIA BE LIABLE TO
   ANY PARTY FOR DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR
   CONSEQUENTIAL DAMAGES ARISING OUT OF THE USE OF THIS SOFTWARE
   AND ITS DOCUMENTATION, EVEN IF THE UNIVERSITY OF CALIFORNIA
   HAS BEEN ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

   THE UNIVERSITY OF CALIFORNIA SPECIFICALLY DISCLAIMS ANY
   WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
   WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
   PURPOSE.  THE SOFTWARE PROVIDED HEREUNDER IS ON AN "AS IS"
   BASIS, AND THE UNIVERSITY OF CALIFORNIA HAS NO OBLIGATION TO
   PROVIDE MAINTENANCE, SUPPORT, UPDATES, ENHANCEMENTS, OR
   MODIFICATIONS.
*/

Also, code derived from MIT's 6.828 course code is subject to the
following license:

/*
 * Copyright (C) 1997 Massachusetts Institute of Technology
 *
 * This software is being provided by the copyright holders under the
 * following license. By obtaining, using and/or copying this software,
 * you agree that you have read, understood, and will comply with the
 * following terms and conditions:
 *
 * Permission to use, copy, modify, distribute, and sell this software
 * and its documentation for any purpose and without fee or royalty is
 * hereby granted, provided that the full text of this NOTICE appears on
 * ALL copies of the software and documentation or portions thereof,
 * including modifications, that you make.
 *
 * THIS SOFTWARE IS PROVIDED "AS IS," AND COPYRIGHT HOLDERS MAKE NO
 * REPRESENTATIONS OR WARRANTIES, EXPRESS OR IMPLIED. BY WAY OF EXAMPLE,
 * BUT NOT LIMITATION, COPYRIGHT HOLDERS MAKE NO REPRESENTATIONS OR
 * WARRANTIES OF MERCHANTABILITY OR FITNESS FOR ANY PARTICULAR PURPOSE OR
 * THAT THE USE OF THE SOFTWARE OR DOCUMENTATION WILL NOT INFRINGE ANY
 * THIRD PARTY PATENTS, COPYRIGHTS, TRADEMARKS OR OTHER RIGHTS. COPYRIGHT
 * HOLDERS WILL BEAR NO LIABILITY FOR ANY USE OF THIS SOFTWARE OR
 * DOCUMENTATION.
 *
 * The name and trademarks of copyright holders may NOT be used in
 * advertising or publicity pertaining to the software without specific,
 * written prior permission. Title to copyright in this software and any
 * associated documentation will at all times remain with copyright
 * holders. See the file AUTHORS which should have accompanied this software
 * for a list of all copyright holders.
 *
 * This file may be derived from previously copyrighted software. This
 * copyright applies only to those changes made by the copyright
 * holders listed in the AUTHORS file. The rest of this file is covered by
 * the copyright notices, if any, listed below.
 */