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Linux: Remove <sys/sysctl.h> and the sysctl function
Linux 5.5 remove the system call in commit
61a47c1ad3a4dc6882f01ebdc88138ac62d0df03 ("Linux: Remove
<sys/sysctl.h>"). Therefore, the compat function is just a stub that
sets ENOSYS.
Due to SHLIB_COMPAT, new ports will not add the sysctl function anymore
automatically.
x32 already lacks the sysctl function, so an empty sysctl.c file is
used to suppress it. Otherwise, a new compat symbol would be added.
Reviewed-by: Adhemerval Zanella <adhemerval.zanella@linaro.org>
This commit is contained in:
Florian Weimer
parent
c4d4419433
commit
076f09afba
6
NEWS
6
NEWS
@ -16,7 +16,11 @@ Major new features:
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Deprecated and removed features, and other changes affecting compatibility:
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[Add deprecations, removals and changes affecting compatibility here]
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* The deprecated <sys/sysctl.h> header and the sysctl function have been
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removed. To support old binaries, the sysctl function continues to
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exist as a compatibility symbol (on those architectures which had it),
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but always fails with ENOSYS. This reflects the removal of the system
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call from all architectures, starting with Linux 5.5.
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Changes to build and runtime requirements:
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@ -1,3 +0,0 @@
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#ifndef _SYS_SYSCTL_H
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#include_next <sys/sysctl.h>
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#endif /* _SYS_SYSCTL_H */
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@ -14,7 +14,6 @@ can make changes.
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* Platform Type:: Determining operating system and basic
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machine type
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* Filesystem Handling:: Controlling/querying mounts
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* System Parameters:: Getting and setting various system parameters
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@end menu
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To get information on parameters of the system that are built into the
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@ -1107,146 +1106,3 @@ to zeroes. It is more widely available than @code{umount2} but since it
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lacks the possibility to forcefully unmount a filesystem is deprecated
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when @code{umount2} is also available.
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@end deftypefun
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@node System Parameters
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@section System Parameters
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This section describes the @code{sysctl} function, which gets and sets
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a variety of system parameters.
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The symbols used in this section are declared in the file @file{sys/sysctl.h}.
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@deftypefun int sysctl (int *@var{names}, int @var{nlen}, void *@var{oldval}, size_t *@var{oldlenp}, void *@var{newval}, size_t @var{newlen})
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@standards{BSD, sys/sysctl.h}
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@safety{@prelim{}@mtsafe{}@assafe{}@acsafe{}}
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@c Direct syscall, Linux only.
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@code{sysctl} gets or sets a specified system parameter. There are so
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many of these parameters that it is not practical to list them all here,
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but here are some examples:
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@itemize @bullet
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@item network domain name
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@item paging parameters
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@item network Address Resolution Protocol timeout time
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@item maximum number of files that may be open
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@item root filesystem device
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@item when kernel was built
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@end itemize
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The set of available parameters depends on the kernel configuration and
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can change while the system is running, particularly when you load and
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unload loadable kernel modules.
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The system parameters with which @code{sysctl} is concerned are arranged
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in a hierarchical structure like a hierarchical filesystem. To identify
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a particular parameter, you specify a path through the structure in a
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way analogous to specifying the pathname of a file. Each component of
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the path is specified by an integer and each of these integers has a
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macro defined for it by @file{sys/sysctl.h}. @var{names} is the path, in
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the form of an array of integers. Each component of the path is one
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element of the array, in order. @var{nlen} is the number of components
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in the path.
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For example, the first component of the path for all the paging
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parameters is the value @code{CTL_VM}. For the free page thresholds, the
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second component of the path is @code{VM_FREEPG}. So to get the free
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page threshold values, make @var{names} an array containing the two
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elements @code{CTL_VM} and @code{VM_FREEPG} and make @var{nlen} = 2.
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The format of the value of a parameter depends on the parameter.
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Sometimes it is an integer; sometimes it is an ASCII string; sometimes
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it is an elaborate structure. In the case of the free page thresholds
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used in the example above, the parameter value is a structure containing
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several integers.
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In any case, you identify a place to return the parameter's value with
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@var{oldval} and specify the amount of storage available at that
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location as *@var{oldlenp}. *@var{oldlenp} does double duty because it
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is also the output location that contains the actual length of the
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returned value.
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If you don't want the parameter value returned, specify a null pointer
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for @var{oldval}.
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To set the parameter, specify the address and length of the new value
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as @var{newval} and @var{newlen}. If you don't want to set the parameter,
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specify a null pointer as @var{newval}.
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If you get and set a parameter in the same @code{sysctl} call, the value
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returned is the value of the parameter before it was set.
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Each system parameter has a set of permissions similar to the
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permissions for a file (including the permissions on directories in its
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path) that determine whether you may get or set it. For the purposes of
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these permissions, every parameter is considered to be owned by the
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superuser and Group 0 so processes with that effective uid or gid may
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have more access to system parameters. Unlike with files, the superuser
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does not invariably have full permission to all system parameters, because
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some of them are designed not to be changed ever.
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@code{sysctl} returns a zero return value if it succeeds. Otherwise, it
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returns @code{-1} and sets @code{errno} appropriately. Besides the
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failures that apply to all system calls, the following are the
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@code{errno} codes for all possible failures:
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@table @code
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@item EPERM
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The process is not permitted to access one of the components of the
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path of the system parameter or is not permitted to access the system parameter
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itself in the way (read or write) that it requested.
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@c There is some indication in the Linux 2.2 code that the code is trying to
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@c return EACCES here, but the EACCES value never actually makes it to the
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@c user.
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@item ENOTDIR
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There is no system parameter corresponding to @var{name}.
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@item EFAULT
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@var{oldval} is not null, which means the process wanted to read the parameter,
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but *@var{oldlenp} is zero, so there is no place to return it.
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@item EINVAL
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@itemize @bullet
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@item
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The process attempted to set a system parameter to a value that is not valid
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for that parameter.
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@item
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The space provided for the return of the system parameter is not the right
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size for that parameter.
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@end itemize
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@item ENOMEM
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This value may be returned instead of the more correct @code{EINVAL} in some
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cases where the space provided for the return of the system parameter is too
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small.
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@end table
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@end deftypefun
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If you have a Linux kernel with the @code{proc} filesystem, you can get
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and set most of the same parameters by reading and writing to files in
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the @code{sys} directory of the @code{proc} filesystem. In the @code{sys}
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directory, the directory structure represents the hierarchical structure
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of the parameters. E.g. you can display the free page thresholds with
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@smallexample
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cat /proc/sys/vm/freepages
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@end smallexample
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@c In Linux, the sysctl() and /proc instances of the parameter are created
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@c together. The proc filesystem accesses the same data structure as
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@c sysctl(), which has special fields in it for /proc. But it is still
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@c possible to create a sysctl-only parameter.
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Some more traditional and more widely available, though less general,
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@glibcadj{} functions for getting and setting some of the same system
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parameters are:
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@itemize @bullet
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@item
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@code{getdomainname}, @code{setdomainname}
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@item
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@code{gethostname}, @code{sethostname} (@xref{Host Identification}.)
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@item
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@code{uname} (@xref{Platform Type}.)
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@end itemize
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@ -74,11 +74,6 @@ for header in "$@"; do
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(finclude/*)
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continue;;
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# sys/sysctl.h produces a deprecation warning and therefore
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# fails compilation with -Werror.
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(sys/sysctl.h)
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continue;;
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# sys/vm86.h is "unsupported on x86-64" and errors out on that target.
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(sys/vm86.h)
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case "$is_x86_64" in
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@ -54,9 +54,7 @@ CFLAGS-malloc.c += -DMORECORE_CLEARS=2
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endif
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ifeq ($(subdir),misc)
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include $(firstword $(wildcard $(sysdirs:=/sysctl.mk)))
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sysdep_routines += adjtimex clone umount umount2 readahead \
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sysdep_routines += adjtimex clone umount umount2 readahead sysctl \
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setfsuid setfsgid epoll_pwait signalfd \
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eventfd eventfd_read eventfd_write prlimit \
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personality epoll_wait tee vmsplice splice \
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@ -71,7 +69,7 @@ CFLAGS-open_by_handle_at.c = -fexceptions -fasynchronous-unwind-tables
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CFLAGS-sync_file_range.c = -fexceptions -fasynchronous-unwind-tables
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CFLAGS-tst-writev.c += "-DARTIFICIAL_LIMIT=(0x80000000-sysconf(_SC_PAGESIZE))"
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sysdep_headers += sys/mount.h sys/acct.h sys/sysctl.h \
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sysdep_headers += sys/mount.h sys/acct.h \
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sys/klog.h \
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sys/user.h sys/prctl.h \
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sys/kd.h sys/soundcard.h sys/vt.h \
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@ -81,7 +79,7 @@ sysdep_headers += sys/mount.h sys/acct.h sys/sysctl.h \
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bits/a.out.h sys/inotify.h sys/signalfd.h sys/eventfd.h \
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sys/timerfd.h sys/fanotify.h bits/eventfd.h bits/inotify.h \
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bits/signalfd.h bits/timerfd.h bits/epoll.h \
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bits/socket_type.h bits/syscall.h bits/sysctl.h \
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bits/socket_type.h bits/syscall.h \
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bits/mman-linux.h bits/mman-shared.h bits/ptrace-shared.h \
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bits/siginfo-arch.h bits/siginfo-consts-arch.h \
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bits/procfs.h bits/procfs-id.h bits/procfs-extra.h \
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@ -177,6 +177,8 @@ libc {
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GLIBC_2.30 {
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getdents64; gettid; tgkill;
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}
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GLIBC_2.32 {
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}
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GLIBC_PRIVATE {
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# functions used in other libraries
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__syscall_rt_sigqueueinfo;
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@ -1 +0,0 @@
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/* Empty file. */
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@ -1,4 +1,5 @@
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/* Copyright (C) 2012-2020 Free Software Foundation, Inc.
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/* sysctl function stub. microblaze version.
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Copyright (C) 2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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@ -15,6 +16,14 @@
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#if defined __x86_64__ && defined __ILP32__
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# error "sysctl system call is unsupported in x32 kernel"
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/* microblaze is special because it has an ABI baseline of 2.18, but
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still includes the __sysctl symbol. */
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#ifdef SHARED
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# include <sysdeps/unix/sysv/linux/sysctl.c>
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strong_alias (___sysctl, ___sysctl2)
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compat_symbol (libc, ___sysctl2, __sysctl, GLIBC_2_2);
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#endif
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@ -1,6 +1,6 @@
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/* Copyright (C) 2011-2020 Free Software Foundation, Inc.
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/* sysctl function stub. powerpc64le version.
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Copyright (C) 2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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Contributed by Chris Metcalf <cmetcalf@tilera.com>, 2011.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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@ -13,20 +13,17 @@
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library. If not, see
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#include <errno.h>
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/* powerpc64le is special because it has an ABI baseline of 2.17, but
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still includes the __sysctl symbol. */
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#include <sysdep.h>
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#include <sys/syscall.h>
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#ifdef SHARED
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/* This deprecated syscall is no longer used (replaced with /proc/sys). */
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int
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sysctl (int *name, int nlen, void *oldval, size_t *oldlenp,
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void *newval, size_t newlen)
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{
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__set_errno (ENOSYS);
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return -1;
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}
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stub_warning (sysctl)
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# include <sysdeps/unix/sysv/linux/sysctl.c>
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strong_alias (___sysctl, ___sysctl2)
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compat_symbol (libc, ___sysctl2, __sysctl, GLIBC_2_2);
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#endif
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@ -1,76 +0,0 @@
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/* Copyright (C) 1996-2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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The GNU C Library is free software; you can redistribute it and/or
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modify it under the terms of the GNU Lesser General Public
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License as published by the Free Software Foundation; either
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version 2.1 of the License, or (at your option) any later version.
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The GNU C Library is distributed in the hope that it will be useful,
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but WITHOUT ANY WARRANTY; without even the implied warranty of
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MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
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Lesser General Public License for more details.
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You should have received a copy of the GNU Lesser General Public
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License along with the GNU C Library; if not, see
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<https://www.gnu.org/licenses/>. */
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#ifndef _SYS_SYSCTL_H
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#define _SYS_SYSCTL_H 1
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#warning "The <sys/sysctl.h> header is deprecated and will be removed."
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#include <features.h>
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#define __need_size_t
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#include <stddef.h>
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/* Prevent more kernel headers than necessary to be included. */
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#ifndef _LINUX_KERNEL_H
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# define _LINUX_KERNEL_H 1
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# define __undef_LINUX_KERNEL_H
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#endif
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#ifndef _LINUX_TYPES_H
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# define _LINUX_TYPES_H 1
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# define __undef_LINUX_TYPES_H
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#endif
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#ifndef _LINUX_LIST_H
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# define _LINUX_LIST_H 1
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# define __undef_LINUX_LIST_H
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#endif
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#ifndef __LINUX_COMPILER_H
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# define __LINUX_COMPILER_H 1
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# define __user
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# define __undef__LINUX_COMPILER_H
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#endif
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#include <linux/sysctl.h>
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#ifdef __undef_LINUX_KERNEL_H
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# undef _LINUX_KERNEL_H
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# undef __undef_LINUX_KERNEL_H
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#endif
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#ifdef __undef_LINUX_TYPES_H
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# undef _LINUX_TYPES_H
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# undef __undef_LINUX_TYPES_H
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#endif
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#ifdef __undef_LINUX_LIST_H
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# undef _LINUX_LIST_H
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# undef __undef_LINUX_LIST_H
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#endif
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#ifdef __undef__LINUX_COMPILER_H
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# undef __LINUX_COMPILER_H
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# undef __user
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# undef __undef__LINUX_COMPILER_H
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#endif
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#include <bits/sysctl.h>
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__BEGIN_DECLS
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/* Read or write system parameters. */
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extern int sysctl (int *__name, int __nlen, void *__oldval,
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size_t *__oldlenp, void *__newval, size_t __newlen) __THROW
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__attribute_deprecated__;
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__END_DECLS
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#endif /* _SYS_SYSCTL_H */
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@ -1,4 +1,4 @@
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/* Read or write system information. Linux version.
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/* sysctl function stub.
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Copyright (C) 1996-2020 Free Software Foundation, Inc.
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This file is part of the GNU C Library.
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@ -17,25 +17,20 @@
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<https://www.gnu.org/licenses/>. */
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#include <errno.h>
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#include <linux/sysctl.h>
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#include <shlib-compat.h>
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#include <sysdep.h>
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#include <sys/syscall.h>
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int
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__sysctl (int *name, int nlen, void *oldval, size_t *oldlenp,
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void *newval, size_t newlen)
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#if SHLIB_COMPAT (libc, GLIBC_2_0, GLIBC_2_32)
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int attribute_compat_text_section
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___sysctl (int *name, int nlen, void *oldval, size_t *oldlenp,
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void *newval, size_t newlen)
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{
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struct __sysctl_args args =
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{
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.name = name,
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.nlen = nlen,
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.oldval = oldval,
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.oldlenp = oldlenp,
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.newval = newval,
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.newlen = newlen
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};
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return INLINE_SYSCALL (_sysctl, 1, &args);
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__set_errno (ENOSYS);
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return -1;
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}
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weak_alias (__sysctl, sysctl)
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compat_symbol (libc, ___sysctl, sysctl, GLIBC_2_0);
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# if SHLIB_COMPAT (libc, GLIBC_2_2, GLIBC_2_17)
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strong_alias (___sysctl, ___sysctl2)
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compat_symbol (libc, ___sysctl2, __sysctl, GLIBC_2_2);
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# endif
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#endif
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@ -1,3 +0,0 @@
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# sysctl system call has been deprecated. It is provided for backward
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# compatility. New target shouldn't add it (see x86_64/x32/sysctl.mk).
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sysdep_routines += sysctl
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2
sysdeps/unix/sysv/linux/x86_64/x32/sysctl.c
Normal file
2
sysdeps/unix/sysv/linux/x86_64/x32/sysctl.c
Normal file
@ -0,0 +1,2 @@
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/* Despite the old base symbol version, x32 does not have a sysctl
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function. */
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@ -1 +0,0 @@
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# X32 doesn't support sysctl.
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