77d3337c9f
Linux specific things to the native fdescfs file system.
Unlike FreeBSD, the Linux fdescfs is a directory containing a symbolic
links to the actual files, which the process has open.
A readlink(2) call on this file returns a full path in case of regular file
or a string in a special format (type:[inode], anon_inode:<file-type>, etc..).
As well as in a FreeBSD, opening the file in the Linux fdescfs directory is
equivalent to duplicating the corresponding file descriptor.
Here we have mutually exclusive requirements:
- in case of readlink(2) call fdescfs lookup() method should return VLNK
vnode otherwise our kern_readlink() fail with EINVAL error;
- in the other calls fdescfs lookup() method should return non VLNK vnode.
For what new vnode v_flag VV_READLINK was added, which is set if fdescfs has beed
mounted with linrdlnk option an modified kern_readlinkat() to properly handle it.
For now For Linux ABI compatibility mount fdescfs volume with linrdlnk option:
mount -t fdescfs -o linrdlnk null /compat/linux/dev/fd
Reviewed by: kib@
MFC after: 1 week
Relnotes: yes
149 lines
4.4 KiB
Groff
149 lines
4.4 KiB
Groff
.\" Copyright (c) 2000 Sheldon Hearn
|
|
.\" All rights reserved.
|
|
.\"
|
|
.\" 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 August 1, 2017
|
|
.Dt LINUX 4
|
|
.Os
|
|
.Sh NAME
|
|
.Nm linux
|
|
.Nd Linux ABI support
|
|
.Sh SYNOPSIS
|
|
To compile support for this ABI into an i386 kernel
|
|
place the following line in your
|
|
kernel configuration file:
|
|
.Bd -ragged -offset indent
|
|
.Cd "options COMPAT_LINUX"
|
|
.Ed
|
|
.Pp
|
|
for an amd64 kernel use:
|
|
.Bd -ragged -offset indent
|
|
.Cd "options COMPAT_LINUX32"
|
|
.Ed
|
|
.Pp
|
|
Alternatively, to load the ABI as a
|
|
module at boot time, place the following line in
|
|
.Xr loader.conf 5 :
|
|
.Bd -literal -offset indent
|
|
linux_load="YES"
|
|
.Ed
|
|
.Sh DESCRIPTION
|
|
The
|
|
.Nm
|
|
module provides limited
|
|
Linux ABI (application binary interface) compatibility
|
|
for userland applications.
|
|
The module provides the following significant facilities:
|
|
.Bl -bullet
|
|
.It
|
|
An image activator
|
|
for correctly branded
|
|
.Xr elf 5
|
|
executable images
|
|
.It
|
|
Special signal handling for activated images
|
|
.It
|
|
Linux to native system call translation
|
|
.El
|
|
.Pp
|
|
It is important to note that the Linux ABI support
|
|
it not provided through an emulator.
|
|
Rather, a true (albeit limited) ABI implementation is provided.
|
|
.Pp
|
|
The following
|
|
.Xr sysctl 8
|
|
tunable variables are available:
|
|
.Bl -tag -width compat.linux.oss_version
|
|
.It compat.linux.osname
|
|
Linux kernel operating system name.
|
|
.It compat.linux.osrelease
|
|
Linux kernel operating system release.
|
|
Changing this to something else is discouraged on non-development systems,
|
|
because it may change the way Linux programs work.
|
|
Recent versions of GNU libc are known to use different syscalls depending
|
|
on the value of this sysctl.
|
|
.It compat.linux.oss_version
|
|
Linux Open Sound System version.
|
|
.El
|
|
.Pp
|
|
The
|
|
.Nm
|
|
module can be linked into the kernel statically with the
|
|
.Dv COMPAT_LINUX
|
|
kernel configuration option
|
|
or loaded as required.
|
|
The following command will load the module
|
|
if it is neither linked into the kernel
|
|
nor already loaded as a module:
|
|
.Bd -literal -offset indent
|
|
if ! kldstat -v | grep -E 'linux(aout|elf)' > /dev/null; then
|
|
kldload linux > /dev/null 2>&1
|
|
fi
|
|
.Ed
|
|
.Pp
|
|
Note that dynamically linked Linux executables
|
|
will require a suitable environment in
|
|
.Pa /compat/linux .
|
|
Specifically, the Linux run-time linker's hints files
|
|
should be correctly initialized.
|
|
For this reason, it is common to execute the following commands
|
|
to prepare the system to correctly run Linux executables:
|
|
.Bd -literal -offset indent
|
|
if [ -x /compat/linux/sbin/ldconfig ]; then
|
|
/compat/linux/sbin/ldconfig -r /compat/linux
|
|
fi
|
|
.Ed
|
|
.Pp
|
|
For information on loading the
|
|
.Nm
|
|
kernel loadable module automatically on system startup,
|
|
see
|
|
.Xr rc.conf 5 .
|
|
This information applies
|
|
regardless of whether the
|
|
.Nm
|
|
module is statically linked into the kernel
|
|
or loaded as a module.
|
|
.Sh FILES
|
|
.Bl -tag -width /compat/linux/dev/fd -compact
|
|
.It Pa /compat/linux
|
|
minimal Linux run-time environment
|
|
.It Pa /compat/linux/dev/fd
|
|
limited Linux file-descriptor file system
|
|
.It Pa /compat/linux/proc
|
|
limited Linux process file system
|
|
.It Pa /compat/linux/sys
|
|
limited Linux system file system
|
|
.El
|
|
.Sh SEE ALSO
|
|
.Xr brandelf 1 ,
|
|
.Xr elf 5 ,
|
|
.Xr fdescfs 5 ,
|
|
.Xr linprocfs 5 ,
|
|
.Xr linsysfs 5
|
|
.Sh HISTORY
|
|
Linux ABI support first appeared in
|
|
.Fx 2.1 .
|