tuneinfo2(2)tuneinfo2(2)NAMEtuneinfo2() - retrieve detailed information about kernel tunable param‐
eters
SYNOPSISDESCRIPTION
This function provides detailed information about one or all kernel
tunable parameters. If a particular parameter is of interest, specify
it by name in tunable. Otherwise, set tunable to NULL and information
will be returned on all kernel tunable parameters (if the supplied buf‐
fer is big enough).
version must always be set to
Information about the selected tunable parameters is returned in struc‐
tures and associated character strings. The buf parameter must specify
an address in the caller's space containing space for these structures
and strings.
bufsize must point to a variable containing the size of the buffer (in
bytes).
Since the character strings are of variable length, the caller must
first ask how much buffer space is needed, then allocate the necessary
buffer space, and then ask for the tunable information. To calculate
the size of the buffer to hold all the tunables, this function should
be called with the parameters buf and bufsize set to NULL and zero,
respectively. The function will return successfully with a return
value of 0 and the variable at bufsize will have been changed to con‐
tain the amount of space needed to hold all of the requested data. See
the example below.
Each structure describes a single tunable parameter, and contains at
least the following fields, in unspecified order:
Location of the character string containing the name of the tunable.
Location of the character string containing an English description of
the parameter.
Location of the character string containing name of the DLKM module in
which the parameter is defined.
This will be a null string for those parameters defined in
the core kernel.
The current value of the parameter.
The boot-time value of the parameter.
The HP-supplied default value of the parameter.
The minimum value of the parameter.
Valid only if the flag is set in the word, below.
The maximum value of the parameter.
Valid only if the flag is set in the word, below.
Note: The minimum and maximum values returned here are rela‐
tively static limits. They will reflect the limitations of
the operating system software, and any limitations placed on
this tunable parameter by the current values of other tunable
parameters. However, they do not reflect any restrictions on
the tunable value based on transient factors like the current
usage pattern of the system.
For example, the maximum value returned for (the maximum num‐
ber of processes a non-root user may have) will be no greater
than the current value of (the maximum number of processes on
the system) minus 5. However, the minimum value returned for
may very well be less than the number of processes that some
user currently has.
A bitmask of zero or more of the following flags:
The value of this parameter can be changed using
The value of this parameter can be changed using
without requiring a reboot.
The values, minima and maxima, for this parameter should be
interpreted
as signed quantities.
The field contains a minimum allowed value for
this parameter.
The field contains a maximum allowed value for
this parameter.
The character string location fields, and can be used to retrieve the
character strings. These fields must be accessed using the macro. The
first parameter of the macro is the pointer to the structure and the
second parameter is one of the four field names above. The result of
the macro will be a pointer to a null-terminated string. See the exam‐
ple below.
RETURN VALUE
If is successful, it returns the number of tunable parameters for which
information was returned and sets the value of bufsize to the amount of
buffer space used. When the parameters buf and bufsize are set to NULL
and zero, respectively; it returns 0 and sets the value of bufsize to
the amount of buffer space that needs to be preallocated.
ERRORS
If this function returns -1 to indicate an error, the global variable
will be set to one of the following values, to indicate the error that
occurred:
The specified tunable parameter does not exist.
The space in buf, as specified in bufsize, is not sufficient
to hold the requested data.
tunable, buf, or bufsize contains an address that is inac‐
cessible.
The Kernel Registry Service was unavailable or encountered an
error.
The version is not supported.
EXAMPLESWARNINGS
Applications and application modules must not share structures unless
it is certain that the value of specified in the header file, is the
same for all modules and involved. The value of may be changed without
notice.
AUTHOR
was developed by Hewlett-Packard Company.
SEE ALSOkctune(1M), gettune(2), settune(2).
The individual tunable parameter manpages in section 5.
tuneinfo2(2)