LINUX(4)

💖 LINUX(4) 💖

okay bestie so this is the linux page from the Kernel Interfaces Manual — yes the whole vibe is "how do I run Linux stuff on FreeBSD without a whole virtual machine, because who has the RAM for that" 🌸

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✨ NAME ✨

linux — Linux ABI support 🐧

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🌈 SYNOPSIS 🌈

so to compile support for this ABI into an i386 kernel, you drop this line into your kernel configuration file:

options COMPAT_LINUX

and for an amd64 kernel you use this one instead:

options COMPAT_LINUX32

OR, if you'd rather load the ABI as a module at boot time, you put this line into loader.conf(5):

linux_load="YES"

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👑 DESCRIPTION 👑

The linux module gives you limited Linux ABI (application binary interface) compatibility, which means you can run a whole bunch of unmodified Linux applications and libraries without needing virtualization or emulation. no cap, it's just vibes ✨

some of the facilities it provides 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

okay important note bestie: dynamically linked Linux executables are gonna need a suitable environment in /compat/linux. That includes native Linux shared libraries, and Linux-specific virtual filesystems. 🫶

to set that whole thing up, install the emulators/linux_base-c7 port or the linux_base-c7 package, and add this line to the rc.conf(5) file:

linux_enable="YES"

and if you want to avoid mounting Linux-specific filesystems at startup, also add this line:

linux_mounts_enable="NO"

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🔥 SYSCTL VARIABLES 🔥

the following variables are available as both sysctl(8) variables and loader(8) tunables:

• compat.linux.debug — enables debugging messages. Set it to 0 to silence them. Defaults to 1. 🤫
• compat.linux.default_openfiles — the default soft openfiles resource limit for Linux applications. Set it to -1 to disable the limit entirely. Defaults to 1024.
• compat.linux.emul_path — path to the Linux run-time environment. Defaults to /compat/linux. 📁
• compat.linux.osname — the Linux kernel operating system name.
• compat.linux.osrelease — the Linux kernel operating system release. ngl, 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 — the 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.

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🎀 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 linrdlnk option, 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)

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🦋 SEE ALSO 🦋

brandelf(1), pty(4), elf(5), fdescfs(5), linprocfs(5), linsysfs(5), tmpfs(5)

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⭐ HISTORY ⭐

Linux ABI support first appeared in FreeBSD 2.1. the way it's been serving looks since forever 💅

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💀 BUGS 💀

Support for some of the Linux-specific system calls and system call arguments is missing. yeah. not everything made it to the group chat, sorry bestie 😭

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and that's the whole page!! mwah 💖 this one came from Debian, dated July 5, 2020 — stay hydrated, back up your rc.conf, and go run some Linux binaries on your FreeBSD box like the icon you are 👑✨