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pullupmsg(9f)

pullupmsg(9F)                  Kernel Functions                  pullupmsg(9F)



NAME
       pullupmsg - concatenate bytes in a message

SYNOPSIS
       #include <sys/stream.h>

       int pullupmsg(mblk_t *mp, ssize_t len);

INTERFACE LEVEL
       Architecture independent level 1 (DDI/DKI).

PARAMETERS
       mp     Pointer  to  the  message  whose  blocks are to be concatenated.
              mblk_t is an instance of the msgb(9S) structure.


       len    Number of bytes to concatenate.


DESCRIPTION
       The pullupmsg() function tries to combine multiple data blocks  into  a
       single  block.  pullupmsg()  concatenates and aligns the first len data
       bytes of the message pointed to by mp. If len equals -1, all  data  are
       concatenated.  If  len  bytes of the same message type cannot be found,
       pullupmsg() fails and returns 0.

RETURN VALUES
       On success, 1 is returned; on failure, 0 is returned.

CONTEXT
       The pullupmsg() function can be called from user, interrupt, or  kernel
       context.

EXAMPLES
       Example 1 Using pullupmsg()



       This is a driver write srv(9E) (service) routine for a device that does
       not support scatter/gather DMA. For all M_DATA messages, the data  will
       be  transferred  to the device with DMA. First, try to pull up the mes‐
       sage into one message block with the pullupmsg() function (line 12). If
       successful, the transfer can be accomplished in one DMA job. Otherwise,
       it must be done one message block at a time (lines  19-22).  After  the
       data  has been transferred to the device, free the message and continue
       processing messages on the queue.



          1 xxxwsrv(q)
          2    queue_t *q;
          3 {
          4       mblk_t *mp;
          5       mblk_t *tmp;
          6       caddr_t dma_addr;
          7     ssize_t dma_len;
          8
          9       while ((mp = getq(q)) != NULL) {
         10               switch (mp->b_datap->db_type) {
         11             case M_DATA:
         12                      if (pullupmsg(mp, -1)) {
         13                            dma_addr = vtop(mp->b_rptr);
         14                              dma_len = mp->b_wptr - mp->b_rptr;
         15                              xxx_do_dma(dma_addr, dma_len);
         16                              freemsg(mp);
         17                              break;
         18                      }
         19                      for (tmp = mp; tmp; tmp = tmp->b_cont) {
         20                            dma_addr = vtop(tmp->b_rptr);
         21                            dma_len = tmp->b_wptr - tmp->b_rptr;
         22                            xxx_do_dma(dma_addr, dma_len);
         23                    }
         24                      freemsg(mp);
         25                      break;
                    . . .
         26                }
         27       }
         28 }


SEE ALSO
       srv(9E), allocb(9F), msgpullup(9F), msgb(9S)


       Writing Device Drivers in Oracle Solaris 11.4


       STREAMS Programming Guide

NOTES
       The pullupmsg() function is not included in the DKI and will be removed
       from the system in a future release. Device driver writers are strongly
       encouraged to use msgpullup(9F) instead of pullupmsg().



Oracle Solaris 11.4               16 Jan 2006                    pullupmsg(9F)
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