Date: Fri, 18 Feb 2022 15:10:28 UTC
The branch stable/13 has been updated by trasz: URL: https://cgit.FreeBSD.org/src/commit/?id=5ed9dc8debc26a04ba91e8bdcc90bdf06213f938 commit 5ed9dc8debc26a04ba91e8bdcc90bdf06213f938 Author: Edward Tomasz Napierala <trasz@FreeBSD.org> AuthorDate: 2022-01-05 08:16:38 +0000 Commit: Edward Tomasz Napierala <trasz@FreeBSD.org> CommitDate: 2022-02-14 19:34:42 +0000 linux(4): man page tweaks Advertise rc.conf method as the right way to enable it, mention file system mapping... and change some wording. Reviewed By: emaste, debdrup, Pau Amma Sponsored By: EPSRC Differential Revision: https://reviews.freebsd.org/D33720 (cherry picked from commit bd8077ee84bd990d88607cc13f36f3da2a4dce10) --- share/man/man4/linux.4 | 88 +++++++++++++++++++++++++++----------------------- 1 file changed, 47 insertions(+), 41 deletions(-) diff --git a/share/man/man4/linux.4 b/share/man/man4/linux.4 index b2d36158c622..b24e3dbc9f79 100644 --- a/share/man/man4/linux.4 +++ b/share/man/man4/linux.4 @@ -24,69 +24,68 @@ .\" .\" $FreeBSD$ .\" -.Dd May 6, 2021 +.Dd January 2, 2022 .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 : +To enable the Linux ABI at boot time, place the following line in +.Xr rc.conf 5 : .Bd -literal -offset indent -linux_load="YES" +linux_enable="YES" .Ed .Sh DESCRIPTION The .Nm module provides limited Linux ABI (application binary interface) compatibility, -making it possible to run many unmodified Linux applications and libraries +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 -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 .It Linux-specific system calls +.It +Special signal handling for Linux processes +.It +Path translation mechanism +.It +Linux-specific virtual file systems .El .Pp -Note that dynamically linked Linux executables -will require a suitable environment in -.Pa /compat/linux . -This includes native Linux shared libraries, and Linux-specific virtual -filesystems. -To set it up, install the +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 Linux process attempts to open +.Pa /etc/passwd , +it will really access +.Pa /compat/linux/etc/passwd , +unless the latter 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 , +use the .Pa emulators/linux_base-c7 -port or the linux_base-c7 -package, and add the following line to the +port or the +.Dv linux_base-c7 +package. +.Pp +To avoid mounting Linux-specific filesystems at startup, add the following +line to the .Xr rc.conf 5 file: .Pp -.Dl linux_enable="YES" -.Pp -To avoid mounting Linux-specific filesystems at startup, also add the following -line: -.Pp .Dl linux_mounts_enable="NO" .Sh SYSCTL VARIABLES The following variables are available as both @@ -114,14 +113,16 @@ 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. -Recent versions of GNU libc are known to use different syscalls depending +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 @@ -134,9 +135,10 @@ Defaults to 0. Disable 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, new Linux images always use credentials of the program -that issued +that issued the .Xr execve 2 call, regardless of the image file mode. +Defaults to 1. .Pp This might be reasonable or even required, because .Fx @@ -146,7 +148,7 @@ could become holes. .Sh FILES .Bl -tag -width /compat/linux/dev/shm -compact .It Pa /compat/linux -minimal Linux run-time environment +Linux run-time environment .It Pa /compat/linux/dev device file system, see .Xr devfs 5 @@ -176,6 +178,10 @@ Linux kernel objects file system, see .Sh HISTORY Linux ABI support first appeared 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.