X286EMUL(1) INTERACTIVE UNIX System 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/386 Release 3.2.
The UNIX system recognizes an attempt to exec(2) a 286 pro-
gram, 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 per-
forms 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.
FILES
/bin/x286emul
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.
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