scsi_init_pkt - prepare a complete SCSI packet
struct scsi_pkt *scsi_init_pkt(struct scsi_address *ap,
struct scsi_pkt *pktp, struct buf *bp, int cmdlen, int statuslen,
int privatelen, int flags, int (*callback)(caddr_t), caddr_t arg);
illumos DDI specific (illumos DDI).
The required length for the SCSI command
descriptor block (CDB) in bytes.
The required length for the SCSI
) in bytes. Valid values are:
No status back.
Return SCSI status byte.
Return status information in a scsi_arq_status
structure. This will include up to 20 bytes of sense data. Please refer to
for more information.
For extra sense packets (PKT_XARQ flag asserted), set
statuslen to be a greater number like, (N + sizeof(struct
scsi_arq_status)) where N is the number of extra bytes beyond the
default 20. For example, N=1 requests 21 bytes of sense, N=235
asks for 255 bytes.
The required length for the pkt_private
A pointer to a callback function, NULL_FUNC, or
The callback function argument.
Target drivers use scsi_init_pkt() to request the transport layer to
allocate and initialize a packet for a SCSI command which possibly
includes a data transfer. If pktp is NULL, a new
scsi_pkt(9S) is allocated using the HBA driver's packet
allocator. The bp is a pointer to a buf(9S) structure. If
bp is non-NULL and contains a valid byte count, the
buf(9S) structure is also set up for DMA transfer using the
HBA driver DMA resources allocator. When bp is allocated
by scsi_alloc_consistent_buf(9F), the PKT_CONSISTENT bit must be
set in the flags argument to ensure proper operation. If
privatelen is non-zero then additional space is allocated for the
pkt_private area of the scsi_pkt(9S). On return
pkt_private points to this additional space. Otherwise
pkt_private is a pointer that is typically used to store the bp
during execution of the command. In this case pkt_private is
NULL on return.
The flags argument is a set of bit flags. Possible bits
This must be set if the DMA
buffer was allocated
. In this case, the HBA
driver will guarantee that the data transfer is properly synchronized before
performing the target driver's command completion callback.
This may be set if the driver can accept a partial
mapping. If set, scsi_init_pkt()
will allocate DMA
resources with the DDI_DMA_PARTIAL
bit set in the DMA flags. The
field of the scsi_pkt(9S)
structure may be returned
with a non-zero value, which indicates the number of bytes for which
was unable to allocate DMA resources. In this case, a
subsequent call to scsi_init_pkt()
may be made for the same pktp
to adjust the DMA resources to the next portion of the transfer.
This sequence should be repeated until the pkt_resid
field is returned
with a zero value, which indicates that with transport of this final portion
the entire original request will have been satisfied.
Setting this flag requests that the HBA
extra sense data for this scsi_pkt(9S)
. The default auto request sense
mechanism returns up to 20 bytes. More than 20 bytes of sense data can be
requested by setting this flag and setting the statuslen
to be the sizeof(struct scsi_arq_status)
number of sense bytes needed beyond 20. For example, set statuslen to be
(sizeof(struct scsi_arq_status) + 5)
for 25 bytes of
When calling scsi_init_pkt() to move already-allocated
DMA resources, the cmdlen, statuslen, and
privatelen fields are ignored.
The last argument arg is supplied to the callback
function when it is invoked.
callback indicates what the allocator routines should do
when resources are not available:
Do not wait for resources. Return a NULL
Wait indefinitely for resources.
callback points to a function which is called when
resources may have become available. callback must return either
0 (indicating that it attempted to allocate resources but again failed
to do so), in which case it is put back on a list to be called again later, or
1 indicating either success in allocating resources or indicating that
it no longer cares for a retry.
When allocating DMA resources, scsi_init_pkt()
returns the scsi_pkt field pkt_resid as the number of residual
bytes for which the system was unable to allocate DMA resources. A
pkt_resid of 0 means that all necessary DMA resources
The scsi_init_pkt() function returns NULL if the packet or
DMA resources could not be allocated. Otherwise, it returns a pointer
to an initialized scsi_pkt(9S). If pktp was not NULL the
return value will be pktp on successful initialization of the packet.
If callback is SLEEP_FUNC, then this routine can be called only
from user-level code. Otherwise, it can be called from user, interrupt, or
kernel context. The callback function may not block or call routines
Example 1 Allocating a Packet Without DMA Resources Attached
To allocate a packet without DMA resources attached,
pkt = scsi_init_pkt(&devp->sd_address, NULL, NULL, CDB_GROUP1,
1, sizeof (struct my_pkt_private *), 0,
Example 2 Allocating a Packet With DMA Resources
To allocate a packet with DMA resources attached use:
pkt = scsi_init_pkt(&devp->sd_address, NULL, bp, CDB_GROUP1,
sizeof(struct scsi_arq_status), 0, 0, NULL_FUNC, NULL);
Example 3 Attaching DMA Resources to a Preallocated
To attach DMA resources to a preallocated packet, use:
pkt = scsi_init_pkt(&devp->sd_address, old_pkt, bp, 0,
0, 0, 0, sd_runout, (caddr_t) sd_unit);
Example 4 Allocating a Packet with Consistent DMA
Since the packet is already allocated, the cmdlen,
statuslen and privatelen are 0. To allocate a packet
with consistent DMA resources attached, use:
bp = scsi_alloc_consistent_buf(&devp->sd_address, NULL,
SENSE_LENGTH, B_READ, SLEEP_FUNC, NULL);
pkt = scsi_init_pkt(&devp->sd_address, NULL, bp, CDB_GROUP0,
sizeof(struct scsi_arq_status), sizeof (struct my_pkt_private *),
PKT_CONSISTENT, SLEEP_FUNC, NULL);
Example 5 Allocating a Packet with Partial DMA
To allocate a packet with partial DMA resources attached,
my_pkt = scsi_init_pkt(&devp->sd_address, NULL, bp, CDB_GROUP0,
1, sizeof (struct buf *), PKT_DMA_PARTIAL,
If a DMA allocation request fails with DDI_DMA_NOMAPPING, the
B_ERROR flag will be set in bp, and the b_error field
will be set to EFAULT.
If a DMA allocation request fails with
DDI_DMA_TOOBIG, the B_ERROR flag will be set in bp, and
the b_error field will be set to EINVAL.