SCSI_SYNC_PKT(9F) Kernel Functions for Drivers SCSI_SYNC_PKT(9F)

NAME

scsi_sync_pkt - synchronize CPU and I/O views of memory

SYNOPSIS

#include <sys/scsi/scsi.h>


void scsi_sync_pkt(struct scsi_pkt *pktp);

INTERFACE LEVEL

illumos DDI specific (illumos DDI).

PARAMETERS

pktp
Pointer to a scsi_pkt(9S) structure.

DESCRIPTION

The scsi_sync_pkt() function is used to selectively synchronize a
CPU's or device's view of the data associated with the SCSI packet
that has been mapped 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 a
SCSI packet is mapped for I/O using scsi_init_pkt(9F) and destroyed
using scsi_destroy_pkt(9F), then an implicit scsi_sync_pkt() will be
performed. However, if the memory object has been modified by either
the device or a CPU after the mapping by scsi_init_pkt(9F), then a
call to scsi_sync_pkt() is required.


If the same scsi_pkt is reused for a data transfer from memory to a
device, then scsi_sync_pkt() must be called before calling
scsi_transport(9F). If the same packet is reused for a data transfer
from a device to memory scsi_sync_pkt() must be called after the
completion of the packet but before accessing the data in memory.

CONTEXT

The scsi_sync_pkt() function may be called from user, interrupt, or
kernel context.

SEE ALSO

tran_sync_pkt(9E), ddi_dma_sync(9F), scsi_destroy_pkt(9F),
scsi_init_pkt(9F), scsi_transport(9F), scsi_pkt(9S)


Writing Device Drivers

January 16, 2006 SCSI_SYNC_PKT(9F)