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Diffstat (limited to 'static/freebsd/man4/linux.4')
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diff --git a/static/freebsd/man4/linux.4 b/static/freebsd/man4/linux.4 new file mode 100644 index 00000000..711ac11e --- /dev/null +++ b/static/freebsd/man4/linux.4 @@ -0,0 +1,198 @@ +.\" 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. +.\" +.Dd May 19, 2024 +.Dt LINUX 4 +.Os +.Sh NAME +.Nm linux +.Nd Linux ABI support +.Sh SYNOPSIS +To enable the Linux ABI at boot time, place the following line in +.Xr rc.conf 5 : +.Bd -literal -offset indent +linux_enable="YES" +.Ed +.Sh DESCRIPTION +The +.Nm +kernel module provides limited Linux ABI (application binary interface) +compatibility, making it possible to run many unmodified Linux applications +without the need for virtualization or emulation. +Some of the facilities provided are: +.Bl -bullet +.It +Linux to native system call translation +.It +Linux-specific system calls +.It +Special signal handling for Linux processes +.It +Path translation mechanism +.It +Linux-specific virtual file systems +.El +.Pp +The path translation mechanism makes Linux processes look up file paths +under +.Va emul_path +(defaulting to +.Pa /compat/linux ) +before +.Pa / . +For example, when a Linux process attempts to open +.Pa /etc/passwd , +it will first access +.Pa /compat/linux/etc/passwd , +falling back to +.Pa /etc/passwd +if the compat path does not exist. +This is used to make sure Linux processes load Linux shared libraries +instead of their similarly-named FreeBSD counterparts, and also +to provide alternative versions of certain other files and virtual +file systems. +.Pp +To install Linux shared libraries and system files into +.Pa /compat/linux , +either use the +.Pa emulators/linux_base-c7 +port or package, +or +.Xr debootstrap 8 +installed from +.Pa sysutils/debootstrap . +.Pp +To avoid mounting Linux-specific filesystems at startup, add the following +line to the +.Xr rc.conf 5 +file: +.Pp +.Dl linux_mounts_enable="NO" +.Sh SYSCTL VARIABLES +The following variables are available as both +.Xr sysctl 8 +variables and +.Xr loader 8 +tunables: +.Bl -tag -width indent +.It Va compat.linux.debug +Enable debugging messages. +Set to 0 to silence them. +Defaults to 3. +A setting of 1 prints debug messages, tells about unimplemented stuff (only +once). +Set to 2 is like 1, but also prints messages about implemented but not tested +stuff (only once). +Setting it to 3 or higher is like 2, but no rate limiting of messages. +.It Va compat.linux.default_openfiles +Default soft openfiles resource limit for Linux applications. +Set to -1 to disable the limit. +Defaults to 1024. +.It Va compat.linux.emul_path +Path to the Linux run-time environment. +Defaults to +.Pa /compat/linux . +.It Va compat.linux.osname +Linux kernel operating system name. +Defaults to "Linux". +.It Va 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. +Some versions of GNU libc are known to use different syscalls depending +on the value of this sysctl. +.It Va compat.linux.oss_version +Linux Open Sound System version. +Defaults to 198144. +.It Va compat.linux.preserve_vstatus +When set to 1, it prevents Linux applications from resetting the +.Xr termios 4 +VSTATUS setting. +From a user perspective, this makes +.Va SIGINFO +work for Linux executables. +Defaults to 1. +.It Va compat.linux.setid_allowed +Enable handling of set-user-ID and set-group-ID mode bits for the new +process image file when image is to be executed under Linux ABI. +When set to 0, new Linux images always use credentials of the program +that issued the +.Xr execve 2 +call, regardless of the image file mode. +This might be reasonable or even required, because +.Fx +does not emulate the Linux environment completely, and missed features +may result in security vulnerabilities. +Defaults to 1. +.It Va compat.linux32.emulate_i386 +In the x86_64 (amd64) world enable the real i386 Linuxulator behavior. +For example, when set to 0, Linux uname -m will return "x86_64" even if +uname itself is a i386 Linux executable. When set to 1, Linux i386 +uname -m will return "i686". +Defaults to 0. +.El +.Sh FILES +.Bl -tag -width /compat/linux/dev/shm -compact +.It Pa /compat/linux +Linux run-time environment +.It Pa /compat/linux/dev +device file system, see +.Xr devfs 4 +.It Pa /compat/linux/dev/fd +file descriptor file system mounted with the +.Cm linrdlnk +option, see +.Xr fdescfs 4 +.It Pa /compat/linux/dev/mqueue +symbolic link to a mqueuefs mount, see +.Xr mqueuefs 4 +.It Pa /compat/linux/dev/shm +in-memory file system, see +.Xr tmpfs 4 +.It Pa /compat/linux/proc +Linux process file system, see +.Xr linprocfs 4 +.It Pa /compat/linux/sys +Linux kernel objects file system, see +.Xr linsysfs 4 +.El +.Sh SEE ALSO +.Xr brandelf 1 , +.Xr fdescfs 4 , +.Xr linprocfs 4 , +.Xr linsysfs 4 , +.Xr mqueuefs 4 , +.Xr pty 4 , +.Xr tmpfs 4 , +.Xr elf 5 +.Sh HISTORY +Linux ABI support first appeared for i386 in +.Fx 2.1 . +Support for amd64 binaries first appeared in +.Fx 10.3 . +Support for arm64 binaries first appeared in +.Fx 12.0 . +.Sh BUGS +Support for some of the Linux-specific system calls and system call arguments +is missing. |