x286emul(1) UNIX System V(C Software Development Set) x286emul(1)
NAME
x286emul - emulate XENIX 80286
SYNOPSIS
x286emul [arg...] prog286
DESCRIPTION
x286emul is an emulator that allows programs from XENIX System V/286
Release 2.3 or SCO's XENIX System V/286 Release 2.3.2 on the Intel 80286
to run on the Intel 80386 processor under UNIX System V.
The UNIX system recognizes an attempt to exec(2) a 286 program, and
automatically exec's the 286 emulator with the 286 program name as an
additional argument. It is not necessary to specify the x286emul
emulator on the command line. The 286 programs can be invoked using the
same command format as on the XENIX System V/286.
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.
The 286 program must be readable for the emulator to read it.
The emulator must have this name and be in /bin if it is to be
automatically invoked when exec(2) is used on a 286 program.
10/89 Page 1