8ec6c4a38b
- map those IPv4 / IPv6 socket options which exist in FreeBSD
+ most of them visually verified to have the same type/layout of arguments
+ not tested with linux programs to behave as intended
- be more human readable for known options which are not handled
- be more verbose for unhandled socket message flags we know about
- print the jail ID in linux_msg if run in a jail
- add possibility to print debug message about known missing parts only once
- add multiple levels of sysctl linux.debug:
1: print debug messages, tell about unimplemented stuff (only once)
2: like 1, but also print messages about implemented but not tested
stuff (only once)
3+: like 2, but no rate limiting of messages
- increase default linux debug level from 1 to 3
We are a lot more verbose in as we need to be (e.g. some of the IP socket
options which are the same, and share the same memory layout, and are
believed to work). The reason is that we have no good testsuite to test those
linux-bits. The LTP or other test suites like the python one, are not fully
up to the task we need. As such the excessive messages about emulated but not
tested socket options.
IMO any MFC (possible, but most probably not by me) should set the default
debug level to 1.
Discussed with: trasz
170 lines
4.9 KiB
Groff
170 lines
4.9 KiB
Groff
.\" Copyright (c) 2000 Sheldon Hearn
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.\" All rights reserved.
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.\"
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.\" Redistribution and use in source and binary forms, with or without
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.\" modification, are permitted provided that the following conditions
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.\" are met:
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.\" 1. Redistributions of source code must retain the above copyright
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.\" notice, this list of conditions and the following disclaimer.
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.\" 2. Redistributions in binary form must reproduce the above copyright
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.\" notice, this list of conditions and the following disclaimer in the
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.\" documentation and/or other materials provided with the distribution.
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.\"
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.\" THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
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.\" ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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.\" IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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.\" ARE DISCLAIMED. IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
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.\" FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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.\" DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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.\" OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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.\" HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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.\" LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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.\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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.\" SUCH DAMAGE.
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.\"
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.\" $FreeBSD$
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.\"
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.Dd July 5, 2020
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.Dt LINUX 4
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.Os
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.Sh NAME
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.Nm linux
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.Nd Linux ABI support
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.Sh SYNOPSIS
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To compile support for this ABI into an i386 kernel
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place the following line in your
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kernel configuration file:
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.Bd -ragged -offset indent
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.Cd "options COMPAT_LINUX"
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.Ed
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.Pp
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for an amd64 kernel use:
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.Bd -ragged -offset indent
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.Cd "options COMPAT_LINUX32"
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.Ed
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.Pp
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Alternatively, to load the ABI as a
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module at boot time, place the following line in
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.Xr loader.conf 5 :
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.Bd -literal -offset indent
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linux_load="YES"
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.Ed
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.Sh DESCRIPTION
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The
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.Nm
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module provides limited Linux ABI (application binary interface) compatibility,
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making it possible to run many unmodified Linux applications and libraries
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without the need for virtualization or emulation.
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Some of the facilities provided are:
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.Bl -bullet
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.It
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An image activator
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for correctly branded
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.Xr elf 5
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executable images
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.It
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Special signal handling for activated images
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.It
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Linux to native system call translation
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.It
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Linux-specific system calls
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.El
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.Pp
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Note that dynamically linked Linux executables
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will require a suitable environment in
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.Pa /compat/linux .
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This includes native Linux shared libraries, and Linux-specific virtual
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filesystems.
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To set it up, install the
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.Pa emulators/linux_base-c7
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port or the linux_base-c7
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package, and add the following line to the
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.Xr rc.conf 5
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file:
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.Pp
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.Dl linux_enable="YES"
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.Pp
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To avoid mounting Linux-specific filesystems at startup, also add the following
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line:
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.Pp
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.Dl linux_mounts_enable="NO"
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.Sh SYSCTL VARIABLES
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The following variables are available as both
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.Xr sysctl 8
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variables and
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.Xr loader 8
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tunables:
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.Bl -tag -width indent
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.It Va compat.linux.debug
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Enable debugging messages.
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Set to 0 to silence them.
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Defaults to 3.
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A setting of 1 prints debug messages, tells about unimplemented stuff (only
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once).
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Set to 2 is like 1, but also prints messages about implemented but not tested
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stuff (only once).
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Setting it to 3 or higher is like 2, but no rate limiting of messages.
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.It Va compat.linux.default_openfiles
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Default soft openfiles resource limit for Linux applications.
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Set to -1 to disable the limit.
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Defaults to 1024.
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.It Va compat.linux.emul_path
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Path to the Linux run-time environment.
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Defaults to
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.Pa /compat/linux .
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.It Va compat.linux.osname
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Linux kernel operating system name.
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.It Va compat.linux.osrelease
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Linux kernel operating system release.
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Changing this to something else is discouraged on non-development systems,
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because it may change the way Linux programs work.
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Recent versions of GNU libc are known to use different syscalls depending
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on the value of this sysctl.
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.It Va compat.linux.oss_version
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Linux Open Sound System version.
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.It Va compat.linux.preserve_vstatus
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When set to 1, it prevents Linux applications from resetting the
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.Xr termios 4
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VSTATUS setting.
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From a user perspective, this makes
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.Va SIGINFO
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work for Linux executables.
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Defaults to 0.
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.El
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.Sh FILES
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.Bl -tag -width /compat/linux/dev/shm -compact
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.It Pa /compat/linux
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minimal Linux run-time environment
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.It Pa /compat/linux/dev
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device file system, see
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.Xr devfs 5
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.It Pa /compat/linux/dev/fd
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file descriptor file system mounted with the
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.Cm linrdlnk
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option, see
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.Xr fdescfs 5
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.It Pa /compat/linux/dev/shm
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in-memory file system, see
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.Xr tmpfs 5
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.It Pa /compat/linux/proc
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Linux process file system, see
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.Xr linprocfs 5
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.It Pa /compat/linux/sys
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Linux kernel objects file system, see
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.Xr linsysfs 5
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.El
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.Sh SEE ALSO
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.Xr brandelf 1 ,
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.Xr pty 4 ,
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.Xr elf 5 ,
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.Xr fdescfs 5 ,
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.Xr linprocfs 5 ,
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.Xr linsysfs 5 ,
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.Xr tmpfs 5
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.Sh HISTORY
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Linux ABI support first appeared in
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.Fx 2.1 .
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.Sh BUGS
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Support for some of the Linux-specific system calls and system call arguments
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is missing.
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