'\" te
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.TH SCSI_SYNC_PKT 9F "Jan 16, 2006"
.SH NAME
scsi_sync_pkt \- synchronize CPU and I/O views of memory
.SH SYNOPSIS
.nf
#include <sys/scsi/scsi.h>



\fBvoid\fR \fBscsi_sync_pkt\fR(\fBstruct scsi_pkt *\fR\fIpktp\fR);
.fi

.SH INTERFACE LEVEL
illumos DDI specific (illumos DDI).
.SH PARAMETERS
.ne 2
.na
\fB\fIpktp\fR\fR
.ad
.RS 8n
Pointer to a \fBscsi_pkt\fR(9S) structure.
.RE

.SH DESCRIPTION
The \fBscsi_sync_pkt()\fR function is used to selectively synchronize a
\fBCPU\fR's or device's view of the data associated with the \fBSCSI\fR packet
that has been mapped for \fBI/O\fR. This may involve operations such as flushes
of \fBCPU\fR or \fBI/O\fR caches, as well as other more complex operations such
as stalling until hardware write buffers have drained.
.sp
.LP
This function need only be called under certain circumstances. When a
\fBSCSI\fR packet is mapped for \fBI/O\fR using \fBscsi_init_pkt\fR(9F) and
destroyed using \fBscsi_destroy_pkt\fR(9F), then an implicit
\fBscsi_sync_pkt()\fR will be performed. However, if the memory object has been
modified by either the device or a \fBCPU\fR after the mapping by
\fBscsi_init_pkt\fR(9F), then a call to \fBscsi_sync_pkt()\fR is required.
.sp
.LP
If the same scsi_pkt is reused for a data transfer from memory to a device,
then \fBscsi_sync_pkt()\fR must be called before calling
\fBscsi_transport\fR(9F). If the same packet is reused for a data transfer from
a device to memory \fBscsi_sync_pkt()\fR must be called after the completion of
the packet but before accessing the data in memory.
.SH CONTEXT
The \fBscsi_sync_pkt()\fR function may be called from user, interrupt, or
kernel context.
.SH SEE ALSO
.BR tran_sync_pkt (9E),
.BR ddi_dma_sync (9F),
.BR scsi_destroy_pkt (9F),
.BR scsi_init_pkt (9F),
.BR scsi_transport (9F),
.BR scsi_pkt (9S)
.sp
.LP
\fIWriting Device Drivers\fR