ddi_umem_iosetup(9F) Kernel Functions for Drivers ddi_umem_iosetup(9F)NAMEddi_umem_iosetup - Setup I/O requests to application memory
SYNOPSIS
#include <sys/ddi.h>
#include <sys/sunddi.h>
struct buf *ddi_umem_iosetup(ddi_umem_cookie_t cookie,off_t off, size_t
len, int direction, dev_t dev, daddr_t blkno, int (*iodone) (struct
buf *), int sleepflag);
INTERFACE LEVEL
Solaris DDI specific (Solaris DDI)
PARAMETERS
cookie The kernel memory cookie allocated by
ddi_umem_lock(9F).
off Offset from the start of the cookie.
len Length of the I/O request in bytes.
direction Must be set to B_READ for reads from the device or
B_WRITE for writes to the device.
dev Device number
blkno Block number on device.
iodone Specific biodone(9F) routine.
sleepflag Determines whether caller can sleep for memory. Possi‐
ble flags are DDI_UMEM_SLEEP to allow sleeping until
memory is available, or DDI_UMEM_NOSLEEP to return NULL
immediately if memory is not available.
DESCRIPTION
The ddi_umem_iosetup(9F) function is used by drivers to setup I/O
requests to application memory which has been locked down using
ddi_umem_lock(9F).
The ddi_umem_iosetup(9F) function returns a pointer to a buf(9S) struc‐
ture corresponding to the memory cookie cookie. Drivers can setup mul‐
tiple buffer structures simultaneously active using the same memory
cookie. The buf(9S) structures can span all or part of the region rep‐
resented by the cookie and can overlap each other. The buf(9S) struc‐
ture can be passed to ddi_dma_buf_bind_handle(9F) to initiate DMA
transfers to or from the locked down memory.
The off parameter specifies the offset from the start of the cookie.
The len parameter represents the length of region to be mapped by the
buffer. The direction parameter must be set to either B_READ or
B_WRITE, to indicate the action that will be performed by the device.
(Note that this direction is in the opposite sense of the VM system's
direction of DDI_UMEMLOCK_READ and DDI_UMEMLOCK_WRITE.) The direction
must be compatible with the flags used to create the memory cookie in
ddi_umem_lock(9F). For example, if ddi_umem_lock() is called with the
flags parameter set to DDI_UMEMLOCK_READ, the direction parameter in
ddi_umem_iosetup() should be set to B_WRITE.
The dev parameter specifies the device to which the buffer is to per‐
form I/O.The blkno parameter represents the block number on the device.
It will be assigned to the b_blkno field of the returned buffer struc‐
ture. The iodone parameter enables the driver to identify a specific
biodone(9F) routine to be called by the driver when the I/O is com‐
plete. The sleepflag parameter determines if the caller can sleep for
memory. DDI_UMEM_SLEEP allocations may sleep but are guaranteed to suc‐
ceed. DDI_UMEM_NOSLEEP allocations do not sleep but may fail (return
NULL) if memory is currently not available.
After the I/O has completed and the buffer structure is no longer
needed, the driver calls freerbuf(9F) to free the buffer structure.
RETURN VALUES
The ddi_umem_iosetup(9F) function returns a pointer to the initialized
buffer header, or NULL if no space is available.
CONTEXT
The ddi_umem_iosetup(9F) function can be called from any context only
if flag is set to DDI_UMEM_NOSLEEP. If DDI_UMEM_SLEEP is set,
ddi_umem_iosetup(9F) can be called from user and kernel context only.
SEE ALSOddi_umem_lock(9F), ddi_dma_buf_bind_handle(9F), freerbuf(9F),
physio(9F), buf(9S)SunOS 5.10 4 Feb 2003 ddi_umem_iosetup(9F)
