query_module(2) System Calls Manual query_module(2)
NAME
query_module - query the kernel for various bits pertaining to modules
SYNOPSIS
#include <linux/module.h>
[[deprecated]] int query_module(const char *name, int which,
void buf[.bufsize], size_t bufsize,
size_t *ret);
DESCRIPTION
Note: This system call is present only before Linux 2.6.
query_module() requests information from the kernel about loadable mod-
ules. 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 cur-
rently 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.
QM_MODULES
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.
QM_DEPS
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 modules.
QM_REFS
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.
QM_SYMBOLS
Returns the symbols and values exported by the kernel or the in-
dicated 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.
QM_INFO
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 cur-
rent status of the module (see the Linux kernel source file in-
clude/linux/module.h). ret is set to the size of the mod-
ule_info structure.
RETURN VALUE
On success, zero is returned. On error, -1 is returned and errno is
set to indicate the error.
ERRORS
EFAULT At least one of name, buf, or ret was outside the program's ac-
cessible address space.
EINVAL Invalid which; or name is NULL (indicating "the kernel"), but
this is not permitted with the specified value of which.
ENOENT No module by that name exists.
ENOSPC The buffer size provided was too small. ret is set to the mini-
mum size needed.
ENOSYS query_module() is not supported in this version of the kernel
(e.g., Linux 2.6 or later).
STANDARDS
Linux.
VERSIONS
Removed in Linux 2.6.
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 declara-
tion 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 in-
terface in your code; alternatively, you can invoke the system call us-
ing syscall(2).
SEE ALSO
create_module(2), delete_module(2), get_kernel_syms(2), init_module(2),
lsmod(8), modinfo(8)
Linux man-pages 6.7 2023-10-31 query_module(2)
Generated by dwww version 1.16 on Tue Dec 16 14:43:55 CET 2025.