x286emul(1)                                              x286emul(1)


       NAME
             x286emul - emulate 80286 XENIX systems

       SYNOPSIS
             x286emul [arg . . .] prog286

       DESCRIPTION
             x286emul is an emulator that allows programs from XENIX
             System V/286 Release 2.3 or XENIX System V/286 Release 2.3.2
             on the Intel 80286 to run on the Intel 80386 processor under
             UNIX System V.

             It is not necessary to invoke x286emul directly; instead, just
             run your programs using the same command line as you would use
             on XENIX System V/286.  When it recognizes an attempt to
             exec(2) a 286 XENIX program, UNIX System V automatically
             exec's x286emul with the arguments to the 286 program, arg . .
             . (if any), followed by the 286 program name, prog286.

             x286emul reads the 286 program's text and data into memory and
             maps them through the LDT [via sysi86(2)] as 286 text and data
             segments.  It also fills in the jam area, which is used by
             XENIX programs to do system calls and signal returns.
             x286emul starts the 286 program by jumping to its entry point.

             When the 286 program attempts to do a system call, x286emul
             takes control.  It does any conversions needed between the 286
             system call and the equivalent 386 system call and performs
             the 386 system call.  The results are converted to the form
             the 286 program expects, and the 286 program is resumed.

             The following are some of the differences between a program
             running on a 286 and a 286 program using x286emul on a 386:

                   Attempts to unlink or write on the 286 program will fail
                   on the 286 with ETXTBSY.  Under x286emul, they will not
                   fail.

                   ptrace(2) is not supported under x286emul.

                   prog286 must be readable and executable by the invoking
                   user (instead of just executable, like other programs),
                   because x286emul, which runs as the invoking user, must
                   be able to read prog286.




                           Copyright 1994 Novell, Inc.               Page 1

      x286emul(1)                                              x286emul(1)


            The emulator must have this name and be in /bin if it is to be
            automatically invoked when exec is used on a 286 program.

      REFERENCES
            exec(2), ptrace(2), sysi86(2)











































                          Copyright 1994 Novell, Inc.               Page 2