NAME
linux —
Linux ABI support
SYNOPSIS
To compile support for this ABI into an i386 kernel place the following line in your kernel configuration file:
options COMPAT_LINUXfor an amd64 kernel use:
options
COMPAT_LINUX32Alternatively, to load the ABI as a module at boot time, place the following line in loader.conf(5):
linux_load="YES"
DESCRIPTION
Thelinux module provides limited Linux ABI (application
binary interface) compatibility, making it possible to run many unmodified
Linux applications and libraries without the need for virtualization or
emulation. Some of the facilities provided are:
- An image activator for correctly branded elf(5) executable images
- Special signal handling for activated images
- Linux to native system call translation
- Linux-specific system calls
Note that dynamically linked Linux executables will require a suitable environment in /compat/linux. This includes native Linux shared libraries, and Linux-specific virtual filesystems. To set it up, install the emulators/linux_base-c7 port or the linux_base-c7 package, and add the following line to the rc.conf(5) file:
linux_enable="YES"To avoid mounting Linux-specific filesystems at startup, also add the following line:
linux_mounts_enable="NO"SYSCTL VARIABLES
The following variables are available as both sysctl(8) variables and loader(8) tunables:
- 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.
- compat.linux.default_openfiles
- Default soft openfiles resource limit for Linux applications. Set to -1 to disable the limit. Defaults to 1024.
- compat.linux.emul_path
- Path to the Linux run-time environment. Defaults to /compat/linux.
- compat.linux.osname
- Linux kernel operating system name.
- 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.
- compat.linux.oss_version
- Linux Open Sound System version.
- compat.linux.preserve_vstatus
- When set to 1, it prevents Linux applications from resetting the termios(4) VSTATUS setting. From a user perspective, this makes SIGINFO work for Linux executables. Defaults to 0.
FILES
- /compat/linux
- minimal Linux run-time environment
- /compat/linux/dev
- device file system, see devfs(5)
- /compat/linux/dev/fd
- file descriptor file system mounted with the
linrdlnkoption, see fdescfs(5) - /compat/linux/dev/shm
- in-memory file system, see tmpfs(5)
- /compat/linux/proc
- Linux process file system, see linprocfs(5)
- /compat/linux/sys
- Linux kernel objects file system, see linsysfs(5)
SEE ALSO
brandelf(1), pty(4), elf(5), fdescfs(5), linprocfs(5), linsysfs(5), tmpfs(5)
HISTORY
Linux ABI support first appeared in FreeBSD 2.1.
BUGS
Support for some of the Linux-specific system calls and system call arguments is missing.