[apple/xnu.git] / osfmk / man / clock_set_attributes.html

<h2>clock_set_attributes</h2>\r<hr>\r<p>\r<strong>Function</strong> - Set a particular clock's attributes.\r<h3>SYNOPSIS</h3>\r<pre>\r<strong>kern_return_t   clock_set_attributes</strong>\r                <strong>(clock_ctrl_t</strong>                     <var>clock_control</var>,\r                 <strong>clock_flavor_t</strong>                          <var>flavor</var>,\r                 <strong>clock_attr_t</strong>                         <var>attribute</var>,\r                 <strong>clock_control</strong>                  <var>attribute_count</var><strong>);</strong>\r</pre>\r<h3>PARAMETERS</h3>\r<dl>\r<p>\r<dt> <var>clock_control</var> \r<dd>\r[in clock-control send right]\rThe control port for the clock.\r<p>\r<dt> <var>flavor</var> \r<dd>\r[in scalar]\rType of information to be set.  Defined values are:\r<dl>\r<p>\r<dt> <strong>CLOCK_ALARM_CURRES</strong>\r<dd>\rThe resolution, in nanoseconds, at which clock alarm and \rsleep timers are currently serviced.  Increasing the current\rresolution will have no impact on any pending clock alarms (i.e. \rthey will go off as originally scheduled).  Decreasing the\rcurrent resolution will truncate any pending alarms to the\rgranularity of the new current resolution.  This value must be a \rmultiple of the minimum resolution and not greater than the \rmaximum resolution of the clock.\r</dl>\r<p>\r<dt> <var>attribute</var> \r<dd>\r[pointer to in scalar]\rNew attribute.\r<p>\r<dt> <var>attribute_count</var> \r<dd>\r[in scalar]\rThe size of the buffer (in natural-sized units).\r</dl>\r<h3>DESCRIPTION</h3>\r<p>\rThe <strong>clock_set_attributes</strong> function sets attributes of\ra clock's operation.\r<h3>NOTES</h3>\r<p>\rThe main reason a clock's current resolution would not always equal its\rminimum resolution is because the overhead of sustaining the\rminimum resolution, \rwhen it is not needed by any existing alarm service client, may be prohibitive \rfor a given hardware platform and underlying clock device.\r<h3>RETURN VALUES</h3>\r<p>\rOnly generic errors apply.\r<h3>RELATED INFORMATION</h3>\r<p>\rFunctions:\r<a href="host_get_clock_control.html"><strong>host_get_clock_control</strong></a>,\r<a href="clock_set_time.html"><strong>clock_set_time</strong></a>,\r<a href="clock_get_attributes.html"><strong>clock_get_attributes</strong></a>.\r