Manual Pages for UNIX Operating System command usage for man ddi_intr_set_nreq

Kernel Functions for Drivers                ddi_intr_set_nreq(9F)



NAME
     ddi_intr_set_nreq - set the number of  interrupts  requested
     for a device driver instance

SYNOPSIS
     #include 



     int ddi_intr_set_nreq(dev_info_t *dip, int nreq);


INTERFACE LEVEL
     Solaris DDI specific (Solaris DDI).

PARAMETERS
     dip     Pointer to the dev_info structure.


     nreq    Number of interrupts requested.


DESCRIPTION
     The  ddi_intr_set_nreq()  function  changes  the  number  of
     interrupts requested by a device driver instance.


     The  nreq  parameter  is  the  total  number  of   interrupt
     resources that this instance of the device driver would like
     to have available. The nreq parameter includes any interrupt
     resources  already  allocated by the driver. For example, if
     the driver instance already has two  MSI-X  vectors  and  it
     wants  two  more,  it should call this function with an nreq
     parameter set to four.


     The nreq parameter can be any value between one and the max-
     imum  number of interrupts supported by the device hardware,
     as reported by a call to the  ddi_intr_get_nintrs(9F)  func-
     tion.  The  driver receives a callback notifying it in cases
     when it must release any previously allocated interrupts, or
     when  it  is allowed to allocate more interrupts as a result
     of its new nreq parameter.


     The ddi_intr_set_nreq()function is not  supported  unless  a
     driver  is  already  consuming  interrupts,  and if it has a
     registered callback handler that can process actions related
     to     changes     in     interrupt     availability.    See
     ddi_cb_register(9F) for an explanation on how to enable this
     functionality.




SunOS 5.11           Last change: 5 Jan 2009                    1






Kernel Functions for Drivers                ddi_intr_set_nreq(9F)



RETURN VALUES
     The ddi_intr_set_nreq() function returns:

     DDI_SUCCESS    on success


     DDI_EINVAL     The operation is  invalid  because  the  nreq
                    parameter is not a legal value


     DDI_ENOTSUP    The operation is not  supported.  The  driver
                    must have a registered callback, and the sys-
                    tem must have interrupt pools implemented.


     DDI_FAILURE    Implementation specific failure


CONTEXT
     These functions can be  called  from  kernel,  non-interrupt
     context.

ATTRIBUTES
     See attributes(5) for descriptions of the  following  attri-
     butes:



     ____________________________________________________________
    |       ATTRIBUTE TYPE        |       ATTRIBUTE VALUE       |
    |_____________________________|_____________________________|
    | Interface Stability         | Private                     |
    |_____________________________|_____________________________|
    | MT-Level                    | MT-Safe                     |
    |_____________________________|_____________________________|


SEE ALSO
     attributes(5),       attach(9E),        ddi_cb_register(9F),
     ddi_intr_alloc(9F), ddi_intr_get_nintrs(9F)

NOTES
     The Interrupt Resource Management feature is limited to dev-
     ice driver instances that are using MSI-X interrupts (inter-
     rupt type DDI_INTR_TYPE_MSIX). Attempts to use this function
     for any other type of interrupts fails with DDI_ENOTSUP.


     The total number of interrupts requested by  the  driver  is
     initially  defined  by  the  count parameter provided by the
     driver's first  call  to  the  ddi_intr_alloc(9F)  function,
     specifically   during   the   driver  instance's  attach(9E)



SunOS 5.11           Last change: 5 Jan 2009                    2






Kernel Functions for Drivers                ddi_intr_set_nreq(9F)



     routine. The ddi_intr_set_nreq() function is  only  used  if
     the  driver instance experiences changes in its I/O load. In
     response to increased I/O  load,  the  driver  may  want  to
     request  additional  interrupt  resources.  In  response  to
     diminished I/O load. the  driver  may  volunteer  to  return
     extra interrupt resources back to the system.

















































SunOS 5.11           Last change: 5 Jan 2009                    3