.\" Copyright (c) 2000 Sheldon Hearn
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.\" $FreeBSD$
.\"
.Dd November 13, 2000
.Dt OSF/1 4 Alpha
.Os
.Sh NAME
.Nm osf1
.Nd OSF/1 ABI support
.Sh SYNOPSIS
To link OSF/1 ABI support into the kernel:
.Cd options     COMPAT_OSF1
.Pp
To load the OSF/1 ABI support kernel module:
.Dl kldload osf1
.Sh DESCRIPTION
The
.Nm
module provides limited
alpha OSF/1 (also known as Digital UNIX, later known as Tru64 UNIX) 
ABI (application binary interface) 
compatibility for userland applications.
The module provides the following significant facilities:
.Bl -bullet
.It
An image activator
for ecoff executable images
.It
Special signal handling for activated images
.It
OSF/1 to native system call translation
.El
.Pp
It is important to note that the OSF/1 ABI support
it not provided through an emulator.
Rather, a true (albeit limited) ABI implementation is provided.
.Pp
The
.Nm
module can be loaded as required.
The following command will load the module
if it is not already loaded as a module:
.Bd -literal -offset indent
if ! kldstat -v | grep -E osf1_ecoff > /dev/null; then
	kldload osf1 > /dev/null 2>&1
fi
.Ed
.Pp
Note that dynamically linked OSF/1 executables
will require a suitable environment in
.Pa /compat/osf1 .
.Pp
For information on loading the
.Nm
kernel loadable module automatically on system startup,
see
.Xr rc.conf 5 .
.Sh FILES
.Bl -tag -width /compat/osf1 -compact
.It Pa /compat/osf1
minimal OSF1 run-time environment
.El
.Sh BUGS
We cannot run OSF/1 applications which rely on the
.Xr pthread 3
API, such as the JDK.
OSF/1's pthreads library uses Mach system calls.  
Mach system calls would be very difficult to support in
.Fx .
.Sh HISTORY
OSF/1 ABI support first appeared in
.Fx 4.0 .