SVR5

bp_mapin(D3)

bp_mapin -- allocate virtual address space for buffer page list

Synopsis (Not in current DDI version)

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

Description

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

Arguments

bp: Pointer to the buffer header structure.

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. Before calling bp_mapin, the offset of the location in the first page where the I/O is to begin is stored in the b_un.b_addr field of the buf structure referenced by bp (for strategy routines, this is done for the driver by the system).

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.

B_PAGEIO will not be set unless the driver has the D_NOBRKUP flag set in devflag(D1).

Context and synchronization

User or blockable context.

Hardware applicability

All

Version applicability

ddi: 1, 2, 3, 4, 5, 5mp, 6, 6mp, 7, 7mp, 7.1, 7.1mp

Differences beteen versions

This function is replaced by buf_breakup(D3) and biostart(D2) in DDI 8.

References

bp_mapout(D3), buf(D4), devflag(D1), strategy(D2)