1 .\" Copyright (c) 2000 Sheldon Hearn
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34 To load the ABI at boot time, place the following line in
36 .Bd -literal -offset indent
42 module provides limited Linux ABI (application binary interface) compatibility,
43 making it possible to run many unmodified Linux applications and libraries
44 without the need for virtualization or emulation.
45 Some of the facilities provided are:
53 Special signal handling for activated images
55 Linux to native system call translation
57 Linux-specific system calls
60 Note that dynamically linked Linux executables
61 will require a suitable environment in
63 This includes native Linux shared libraries, and Linux-specific virtual
65 To set it up, install the
66 .Pa emulators/linux_base-c7
67 port or the linux_base-c7
68 package, and add the following line to the
72 .Dl linux_enable="YES"
74 To avoid mounting Linux-specific filesystems at startup, also add the following
77 .Dl linux_mounts_enable="NO"
79 The following variables are available as both
84 .Bl -tag -width indent
85 .It Va compat.linux.debug
86 Enable debugging messages.
87 Set to 0 to silence them.
89 A setting of 1 prints debug messages, tells about unimplemented stuff (only
91 Set to 2 is like 1, but also prints messages about implemented but not tested
93 Setting it to 3 or higher is like 2, but no rate limiting of messages.
94 .It Va compat.linux.default_openfiles
95 Default soft openfiles resource limit for Linux applications.
96 Set to -1 to disable the limit.
98 .It Va compat.linux.emul_path
99 Path to the Linux run-time environment.
102 .It Va compat.linux.osname
103 Linux kernel operating system name.
104 .It Va compat.linux.osrelease
105 Linux kernel operating system release.
106 Changing this to something else is discouraged on non-development systems,
107 because it may change the way Linux programs work.
108 Recent versions of GNU libc are known to use different syscalls depending
109 on the value of this sysctl.
110 .It Va compat.linux.oss_version
111 Linux Open Sound System version.
112 .It Va compat.linux.preserve_vstatus
113 When set to 1, it prevents Linux applications from resetting the
116 From a user perspective, this makes
118 work for Linux executables.
120 .It Va compat.linux.setid_allowed
121 Disable handling of set-user-ID and set-group-ID mode bits for the new
122 process image file when image is to be executed under Linux ABI.
123 When set, new Linux images always use credentials of the program
126 call, regardless of the image file mode.
128 This might be reasonable or even required, because
130 does not emulate Linux environment completely, and missed features
134 .Bl -tag -width /compat/linux/dev/shm -compact
136 minimal Linux run-time environment
137 .It Pa /compat/linux/dev
138 device file system, see
140 .It Pa /compat/linux/dev/fd
141 file descriptor file system mounted with the
145 .It Pa /compat/linux/dev/shm
146 in-memory file system, see
148 .It Pa /compat/linux/proc
149 Linux process file system, see
151 .It Pa /compat/linux/sys
152 Linux kernel objects file system, see
164 Linux ABI support first appeared in
167 Support for some of the Linux-specific system calls and system call arguments