bp_mapin(D3)

NAME
     bp_mapin - allocate virtual address space for buffer page list

SYNOPSIS
     #include <sys/types.h>
     #include <sys/buf.h>
     #include <sys/ddi.h>
     void bp_mapin(struct buf_t *bp);

   Arguments
     bp        Pointer to the buffer header structure.

DESCRIPTION
     The bp_mapin function is used to map virtual address space to a page list
     maintained by the buffer header [see buf(D4)] during a paged-I/O request.

   Return Values
     None

USAGE
     A paged-I/O request is identified by the B_PAGEIO flag being set in the
     b_flags field of the buffer header passed to a driver's strategy(D2)
     routine.

     bp_mapin allocates system virtual address space, maps that space to the
     page list, and returns the new virtual address in the b_un.b_addr field
     of the buf structure.  This address is the virtual address of the start
     of the page mappings, plus the offset given by the original value of bp-
     >b_un.b_addr.  After the I/O completes, the virtual address space can be
     deallocated using the bp_mapout(D3) function.

   Level
     Base only.

   Synchronization Constraints
     This routine may sleep if virtual space is not immediately available.

     Driver-defined basic locks and read/write locks may not be held across
     calls to this function.

     Driver-defined sleep locks may be held across calls to this function.

REFERENCES
     bp_mapout(D3), buf(D4), strategy(D2)