svcadm(8)을 검색하려면 섹션에서 8 을 선택하고, 맨 페이지 이름에 svcadm을 입력하고 검색을 누른다.
ddi_dma_sync(9f)
ddi_dma_sync(9F) Kernel Functions ddi_dma_sync(9F)
NAME
ddi_dma_sync - synchronize CPU and I/O views of memory
SYNOPSIS
#include <sys/ddi.h>
#include <sys/sunddi.h>
int ddi_dma_sync(ddi_dma_handle_t handle, off_t offset,
size_t length, uint_t type);
INTERFACE LEVEL
Solaris DDI specific (Solaris DDI).
PARAMETERS
handle The handle filled in by a call to ddi_dma_alloc_handle(9F).
offset The offset into the object described by the handle.
length The length, in bytes, of the area to synchronize. When length
is zero, the entire range starting from offset to the end of
the object has the requested operation applied to it.
type Indicates the caller's desire about what view of the memory
object to synchronize. The possible values are
DDI_DMA_SYNC_FORDEV, DDI_DMA_SYNC_FORCPU and
DDI_DMA_SYNC_FORKERNEL.
DESCRIPTION
The ddi_dma_sync() function is used to selectively synchronize either a
DMA device's or a CPU's view of a memory object that has DMA resources
allocated for I/O . This may involve operations such as flushes of CPU
or I/O caches, as well as other more complex operations such as
stalling until hardware write buffers have drained.
This function need only be called under certain circumstances. When re‐
sources are allocated for DMA using ddi_dma_addr_bind_handle() or
ddi_dma_buf_bind_handle(), an implicit ddi_dma_sync() is done. When DMA
resources are deallocated using ddi_dma_unbind_handle(9F), an implicit
ddi_dma_sync() is done. However, at any time between DMA resource allo‐
cation and deallocation, if the memory object has been modified by ei‐
ther the DMA device or a CPU and you wish to ensure that the change is
noticed by the party that did not do the modifying, a call to
ddi_dma_sync() is required. This is true independent of any attributes
of the memory object including, but not limited to, whether or not the
memory was allocated for consistent mode I/O (see ddi_dma_mem_al‐
loc(9F)) or whether or not DMA resources have been allocated for con‐
sistent mode I/O (see ddi_dma_addr_bind_handle(9F) or
ddi_dma_buf_bind_handle(9F)).
If a consistent view of the memory object must be ensured between the
time DMA resources are allocated for the object and the time they are
deallocated, you must call ddi_dma_sync() to ensure that either a CPU
or a DMA device has such a consistent view.
What to set type to depends on the view you are trying to ensure con‐
sistency for. If the memory object is modified by a CPU, and the object
is going to be read by the DMA engine of the device, use
DDI_DMA_SYNC_FORDEV. This ensures that the device's DMA engine sees any
changes that a CPU has made to the memory object. If the DMA engine for
the device has written to the memory object, and you are going to read
(with a CPU) the object (using an extant virtual address mapping that
you have to the memory object), use DDI_DMA_SYNC_FORCPU. This ensures
that a CPU's view of the memory object includes any changes made to the
object by the device's DMA engine. If you are only interested in the
kernel's view (kernel-space part of the CPU's view) you may use
DDI_DMA_SYNC_FORKERNEL. This gives a hint to the system—that is, if it
is more economical to synchronize the kernel's view only, then do so;
otherwise, synchronize for CPU.
RETURN VALUES
The ddi_dma_sync() function returns:
DDI_SUCCESS Caches are successfully flushed.
DDI_FAILURE The address range to be flushed is out of the address
range established by ddi_dma_addr_bind_handle(9F) or
ddi_dma_buf_bind_handle(9F).
CONTEXT
The ddi_dma_sync() function can be called from user, interrupt, or ker‐
nel context.
SEE ALSO
ddi_dma_addr_bind_handle(9F), ddi_dma_alloc_handle(9F),
ddi_dma_buf_bind_handle(9F), ddi_dma_mem_alloc(9F), ddi_dma_unbind_han‐
dle(9F)
Writing Device Drivers in Oracle Solaris 11.4
Oracle Solaris 11.4 16 Jan 2006 ddi_dma_sync(9F)