query_module(2) — Linux manual page


QUERY_MODULE(2)         Linux Programmer's Manual        QUERY_MODULE(2)

NAME         top

       query_module - query the kernel for various bits pertaining to

SYNOPSIS         top

       #include <linux/module.h>

       int query_module(const char *name, int which, void *buf,
                        size_t bufsize, size_t *ret);

       Note: No declaration of this system call is provided in glibc
       headers; see NOTES.

DESCRIPTION         top

       Note: This system call is present only in kernels before Linux

       query_module() requests information from the kernel about
       loadable modules.  The returned information is placed in the
       buffer pointed to by buf.  The caller must specify the size of
       buf in bufsize.  The precise nature and format of the returned
       information depend on the operation specified by which.  Some
       operations require name to identify a currently loaded module,
       some allow name to be NULL, indicating the kernel proper.

       The following values can be specified for which:

       0      Returns success, if the kernel supports query_module().
              Used to probe for availability of the system call.

              Returns the names of all loaded modules.  The returned
              buffer consists of a sequence of null-terminated strings;
              ret is set to the number of modules.

              Returns the names of all modules used by the indicated
              module.  The returned buffer consists of a sequence of
              null-terminated strings; ret is set to the number of

              Returns the names of all modules using the indicated
              module.  This is the inverse of QM_DEPS.  The returned
              buffer consists of a sequence of null-terminated strings;
              ret is set to the number of modules.

              Returns the symbols and values exported by the kernel or
              the indicated module.  The returned buffer is an array of
              structures of the following form

                  struct module_symbol {
                      unsigned long value;
                      unsigned long name;

              followed by null-terminated strings.  The value of name is
              the character offset of the string relative to the start
              of buf; ret is set to the number of symbols.

              Returns miscellaneous information about the indicated
              module.  The output buffer format is:

                  struct module_info {
                      unsigned long address;
                      unsigned long size;
                      unsigned long flags;

              where address is the kernel address at which the module
              resides, size is the size of the module in bytes, and
              flags is a mask of MOD_RUNNING, MOD_AUTOCLEAN, and so on,
              that indicates the current status of the module (see the
              Linux kernel source file include/linux/module.h).  ret is
              set to the size of the module_info structure.

RETURN VALUE         top

       On success, zero is returned.  On error, -1 is returned and errno
       is set to indicate the error.

ERRORS         top

       EFAULT At least one of name, buf, or ret was outside the
              program's accessible address space.

       EINVAL Invalid which; or name is NULL (indicating "the kernel"),
              but this is not permitted with the specified value of

       ENOENT No module by that name exists.

       ENOSPC The buffer size provided was too small.  ret is set to the
              minimum size needed.

       ENOSYS query_module() is not supported in this version of the
              kernel (e.g., the kernel is version 2.6 or later).

VERSIONS         top

       This system call is present on Linux only up until kernel 2.4; it
       was removed in Linux 2.6.

CONFORMING TO         top

       query_module() is Linux-specific.

NOTES         top

       Some of the information that was formerly available via
       query_module() can be obtained from /proc/modules,
       /proc/kallsyms, and the files under the directory /sys/module.

       The query_module() system call is not supported by glibc.  No
       declaration is provided in glibc headers, but, through a quirk of
       history, glibc does export an ABI for this system call.
       Therefore, in order to employ this system call, it is sufficient
       to manually declare the interface in your code; alternatively,
       you can invoke the system call using syscall(2).

SEE ALSO         top

       create_module(2), delete_module(2), get_kernel_syms(2),
       init_module(2), lsmod(8), modinfo(8)

COLOPHON         top

       This page is part of release 5.13 of the Linux man-pages project.
       A description of the project, information about reporting bugs,
       and the latest version of this page, can be found at

Linux                          2021-03-22                QUERY_MODULE(2)

Pages that refer to this page: create_module(2)delete_module(2)get_kernel_syms(2)init_module(2)syscalls(2)