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   7 .TH AWRITE 9E "February 15, 2020"
   8 .SH NAME
   9 awrite \- asynchronous write to a device
  10 .SH SYNOPSIS
  11 .nf
  12 #include <sys/uio.h>
  13 #include <sys/aio_req.h>
  14 #include <sys/cred.h>
  15 #include <sys/ddi.h>
  16 #include <sys/sunddi.h>
  17 
  18 \fBint prefix\fR\fBawrite\fR(\fBdev_t\fR \fIdev\fR, \fBstruct aio_req *\fR\fIaio_reqp\fR,
  19      \fBcred_t *\fR\fIcred_p\fR);
  20 .fi
  21 
  22 .SH INTERFACE LEVEL
  23 Solaris \fBDDI \fRspecific (Solaris DDI). This entry point is optional. Drivers
  24 that do not support an \fBawrite()\fR entry point should use \fBnodev\fR(9F)
  25 .SH PARAMETERS
  26 .ne 2
  27 .na
  28 \fB\fIdev\fR\fR
  29 .ad
  30 .RS 12n
  31 Device number.
  32 .RE
  33 
  34 .sp
  35 .ne 2
  36 .na
  37 \fB\fIaio_reqp\fR\fR
  38 .ad
  39 .RS 12n
  40 Pointer to the \fBaio_req\fR(9S) structure that describes where the data is
  41 stored.
  42 .RE
  43 
  44 .sp
  45 .ne 2
  46 .na
  47 \fB\fIcred_p\fR\fR
  48 .ad
  49 .RS 12n
  50 Pointer to the credential structure.
  51 .RE
  52 
  53 .SH DESCRIPTION
  54 The driver's \fBawrite()\fR routine is called to perform an asynchronous write.
  55 \fBgetminor\fR(9F) can be used to access the minor number component of the
  56 \fIdev\fR argument. \fBawrite()\fR may use the credential structure pointed to
  57 by \fIcred_p\fR to check for superuser access by calling \fBdrv_priv\fR(9F).
  58 The \fBawrite()\fR routine may also examine the \fBuio\fR(9S) structure
  59 through the \fBaio_req\fR structure pointer, \fBaio_reqp\fR. \fBawrite()\fR
  60 must call \fBaphysio\fR(9F) with the \fBaio_req\fR pointer and a pointer to the
  61 driver's \fBstrategy\fR(9E) routine.
  62 .sp
  63 .LP
  64 No fields of the \fBuio\fR(9S) structure pointed to by \fBaio_req\fR, other
  65 than \fBuio_offset\fR or \fBuio_loffset\fR, may be modified for non-seekable
  66 devices.
  67 .SH RETURN VALUES
  68 The \fBawrite()\fR routine should return  \fB0\fR for success, or the
  69 appropriate error number.
  70 .SH CONTEXT
  71 This function is called from user context only.
  72 .SH EXAMPLES
  73 \fBExample 1 \fRUsing the \fBawrite()\fR routine:
  74 .sp
  75 .LP
  76 The following is an example of an \fBawrite()\fR routine:
  77 
  78 .sp
  79 .in +2
  80 .nf
  81 static int
  82 xxawrite(dev_t dev, struct aio_req *aio, cred_t *cred_p)
  83 {
  84         int instance;
  85         struct xxstate *xsp;
  86 
  87         instance = getminor(dev);
  88         xsp = ddi_get_soft_state(statep, instance);
  89         /*Verify soft state structure has been allocated */
  90         if (xsp == NULL)
  91                  return (ENXIO);
  92         return (aphysio(xxstrategy, anocancel, dev, B_WRITE, \e
  93         xxminphys, aio));
  94 }
  95 .fi
  96 .in -2
  97 
  98 .SH SEE ALSO
  99 \fBwrite\fR(2), \fBaiowrite\fR(3C), \fBaread\fR(9E), \fBread\fR(9E),
 100 \fBstrategy\fR(9E), \fBwrite\fR(9E), \fBanocancel\fR(9F), \fBaphysio\fR(9F),
 101 \fBddi_get_soft_state\fR(9F), \fBdrv_priv\fR(9F), \fBgetminor\fR(9F),
 102 \fBminphys\fR(9F), \fBnodev\fR(9F), \fBaio_req\fR(9S), \fBcb_ops\fR(9S),
 103 \fBuio\fR(9S)
 104 .sp
 105 .LP
 106 \fIWriting Device Drivers\fR
 107 .SH BUGS
 108 There is no way other than calling \fBaphysio\fR(9F) to accomplish an
 109 asynchronous write.