Add a manual page for the cloudabi and cloudabi64 kernel modules.

CloudABI has two separate kernel modules: cloudabi and cloudabi64. The
first module contains all the pointer size independent code, whereas
cloudabi64 contains the actual 64-bits specific system calls and the ELF
loader.

Reviewed by:	wblock
Obtained from:	https://github.com/NuxiNL/freebsd
Differential Revision:	https://reviews.freebsd.org/D3258

share/man/man4/Makefile

@@ -96,6 +96,7 @@ MAN=	aac.4 \
 	cdce.4 \
 	ch.4 \
 	ciss.4 \
+	cloudabi.4 \
 	cm.4 \
 	cmx.4 \
 	${_coretemp.4} \
@@ -583,6 +584,7 @@ MLINKS+=bwn.4 if_bwn.4
 MLINKS+=${_bxe.4} ${_if_bxe.4}
 MLINKS+=cas.4 if_cas.4
 MLINKS+=cdce.4 if_cdce.4
+MLINKS+=cloudabi.4 cloudabi64.4
 MLINKS+=crypto.4 cryptodev.4
 MLINKS+=cue.4 if_cue.4
 MLINKS+=cxgb.4 if_cxgb.4

share/man/man4/cloudabi.4

@@ -0,0 +1,103 @@
+.\" Copyright (c) 2015 Nuxi, https://nuxi.nl/
+.\"
+.\" Redistribution and use in source and binary forms, with or without
+.\" modification, are permitted provided that the following conditions
+.\" are met:
+.\" 1. Redistributions of source code must retain the above copyright
+.\"    notice, this list of conditions and the following disclaimer.
+.\" 2. Redistributions in binary form must reproduce the above copyright
+.\"    notice, this list of conditions and the following disclaimer in the
+.\"    documentation and/or other materials provided with the distribution.
+.\"
+.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+.\" ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+.\" SUCH DAMAGE.
+.\"
+.\" $FreeBSD$
+.Dd July 31, 2015
+.Dt CLOUDABI 4
+.Os
+.Sh NAME
+.Nm cloudabi ,
+.Nm cloudabi64
+.Nd CloudABI support
+.Sh SYNOPSIS
+Support for 64-bit CloudABI executables can be compiled into the kernel
+by adding this line to the kernel configuration file:
+.Bd -ragged -offset indent
+.Cd "options COMPAT_CLOUDABI64"
+.Ed
+.Pp
+CloudABI support can also be loaded at boot time from
+.Xr loader.conf 5 :
+.Bd -literal -offset indent
+cloudabi_load="YES"
+cloudabi64_load="YES"
+.Ed
+.Sh DESCRIPTION
+CloudABI is a POSIX-like pure capability-based runtime environment,
+similar to
+.Xr capsicum 4 .
+It can be used to develop applications that are cross-platform,
+easier to test,
+and hardened against security exploits.
+.Pp
+Support for CloudABI on
+.Fx
+consists of two separate kernel modules.
+The
+.Nm cloudabi
+kernel module implements all of the system calls that do not depend on
+data structures that differ between architectures.
+.Pp
+The
+.Nm cloudabi64
+kernel module provides implementations of all of the machine-dependent
+system calls.
+It assumes that pointers stored in data structures provided as system
+call arguments are 64 bits in size.
+It also provides the image activator that loads and starts 64-bit ELF
+executables.
+.Pp
+Though the
+.Nm cloudabi
+module can be loaded on any architecture supported by
+.Fx ,
+the
+.Nm cloudabi64
+module is only available for amd64.
+.Pp
+A full cross compilation toolchain for CloudABI is available in the
+.Pa devel/cloudabi-toolchain
+port.
+.Pp
+The
+.Pa sysutils/cloudabi-utils
+port provides the
+.Xr cloudabi-run 1
+utility.
+.Xr cloudabi-run 1
+can be used to safely execute CloudABI processes with access to a
+restricted set of resources.
+.Sh SEE ALSO
+.Xr cloudabi-run 1 ,
+.Xr capsicum 4 ,
+.Xr linux 4 ,
+.Xr elf 5
+.Pp
+cloudlibc on GitHub:
+.Pa https://github.com/NuxiNL/cloudlibc .
+.Sh HISTORY
+CloudABI support first appeared in
+.Fx 11.0 .
+.Sh AUTHORS
+Nuxi:
+.Pa https://nuxi.nl/ .