Dell Emulex Family of Adapters - Manual (Page 981)

Emulex Drivers Version 10.2 for Linux User Manual P010081-01A Rev. A
Appendix F. lpfc Driver BlockGuard Functionality
lpfc Driver Module Parameters
981
lpfc Driver Module Parameters
The lpfc driver has two module parameters: lpfc_prot_mask and lpfc_prot_guard.
Using these parameters, you can control which DIF capabilities the lpfc driver registers
with the Linux SCSI subsystem. This in turn controls which initiator operations
(BlockGuard profiles) are used during I/O operations. These parameters are set up
when the driver loads and cannot be changed while the driver is running.
lpfc_prot_mask
This parameter controls the DIF operations that the driver registers with the operating
system. The operating system selects an operation to use for each I/O command that
matches the HBA DIF capability. The driver indicates its capabilities by the operations
it registers with the operating system.
If the parameter is not passed to the driver, the default DIX_TYPE0 is used.
The SCSI layer will typically use the bit masks in Table F-2 to determine how to place
the protection data associated with I/Os to the SCSI Host. The default value for
lpfc_prot_mask is to allow all of the options. Table F-3 shows how protection data gets
placed for each supported profile.
READ_PASS Protected Protected Reads the data and protection data
from the target on the SAN. The
HBA will verify data integrity and
transfer both data and protection
data to the Initiator host. The HBA
can convert the protection data
guard tag from CRC to IP CSUM.
WRITE_PASS Protected Protected Transfers the data and protection
data from the Initiator host to the
HBA. The HBA will verify protection
data and write both data and
protection data to the target on the
SAN. The HBA can convert the
protection data guard tag from IP
CSUM to CRC.
Table F-1 Initiator Operations (Continued)
Initiator
Operation
Initiator Host <-> HBA HBA <-> Target Comment
Table F-2 lpfc_prot_mask Protection Types
Flag Value Indicates Description
SHOST_DIF_TYPE1_PROTECTION 1 HBA supports T10 DIF Type 1 HBA to Target Type 1
Protection
SHOST_DIX_TYPE0_PROTECTION 8 HBA supports DIX Type 0 Host to HBA protection only
SHOST_DIX_TYPE1_PROTECTION 16 HBA supports DIX Type 1 Host to HBA Type 1
protection