uiophysio(D3X)

NAME
     uiophysio - set up user data space for I/O

SYNOPSIS
     #include <sys/types.h>
     #include <sys/buf.h>
     #include <sys/uio.h>
     #include <sys/ddi.h>

     int uiophysio(int (*strat)(struct buf *), struct buf *bp, dev_t dev,
          int rwflag, struct uio *uiop);

   Arguments
     strat
          Address of the driver routine.

     bp   Pointer to the buf(D4) structure describing the I/O request.

     dev  External device number.

     rwflag
          Flag indicating whether the access is a read or a write.

     uiop Pointer to the uio(D4) structure that defines the user space of the
          I/O request.

DESCRIPTION
     uiophysio prepares the user's address space for DMA I/O and encapsulates
     the transfer information in a buffer header.

   Return Values
     uiophysio returns 0 if the result is successful, or the appropriate error
     number on failure. If a partial transfer occurs, the uio structure is
     updated to indicate the amount not transferred and an error is returned.
     uiophysio returns the ENOSPC error if an attempt is made to read beyond
     the end of the device. If a read is performed at the end of the device, 0
     is returned. ENOSPC is also returned if an attempt is made to write at or
     beyond the end of a the device. EFAULT is returned if user memory is not
     valid. EAGAIN is returned if uiophysio could not lock all of the pages.

USAGE
     uiophysio performs the following functions:

     o    Sets up a buffer header describing the transfer; faults pages in and
          locks the pages impacted by the I/O transfer so they can't be
          swapped out

     o    Calls the routine named in the strat parameter, passing a pointer to
          a buf structure
     o    Sleeps until the transfer is complete and is awakened by a call to
          biodone(D3) from the driver's I/O completion handler

     o    Performs the necessary cleanup and updates, then returns to the
          driver routine

     If bp is set to NULL, a buffer is allocated temporarily and freed after
     the transfer completes.

     If rwflag is set to B_READ, the direction of the data transfer will be
     from the kernel or device to the user's buffer. If rwflag is set to
     B_WRITE, the direction of the data transfer will be from the user's
     buffer to the kernel or device.

   Level
     Base only.

   See Also
     buf(D4), ioctl(D2), read(D2), strategy(D2), physiock(D3), uio(D4),
     write(D2)