DCD(7)

Description

The DCD subsystem adds support for non-SCSI devices under SDI for use with related target drivers. This subsystem is accessed indirectly by opening an appropriate target driver to access a target device that is on a DCD controller.

It is also possible to access this subsystem using the pass-through driver. To find the appropriate device to use, while the device is being accessed through the target driver, use the B_GETDEV ioctl to get the major and minor numbers of the pass-though node. This node can either be created or opened for use.

ioctl calls

B_GETDEV

Return the pass-through major and minor numbers to the calling utility to allow creation of a pass-through special device file.

The following commands should be used to get and set device geometry. These return or accept the structure dsk_geom defined in the sdi.h header file.

HA_GETPARMS

Return host adapter's idea of the device geometry. This is what the system uses during the boot sequence. This is used by certain target drivers.

HA_SETPARMS

Set the host adapter's idea of the device geometry. Note that some host adapters do not support this ioctl and will result in an error.

HA_GETPPARMS

Return the actual device geometry. This is the actual as opposed to virtual device geometry.

The DCD driver halt routine that is executed during shutdown allows the controller enough time to flush the disk cache (if present) to disk. Although two seconds are allowed for this flush, the actual timeout value is an external variable in the DCD space.c file. You can modify this variable if a specific controller needs more time to clear the cache.

Files

/usr/include/sys/sdi.h

/usr/include/sys/sdi_edt.h

References