SDI peripheral hot add/remove

SDI hot add/remove is the ability to add and remove SDI peripheral (target) devices from a running system. This feature works with all packages written for any SDI versions, including mounted filesystems, the Veritas Volume Manager, and raw device access through /dev/rdsk and /dev/rmt.

The hotplug feature, which supports adding and removing HBA devices, provides similar functionality for SDI version 4 HBA drivers that use DDI version 8/8mp may also support the

Coding in HBA drivers

To support device hot add/remove, an HBA driver needs to include the following code:

• It must have a devflag(D1) with HBA_HOT set when the HBA_INFO macro (documented on the hba_info(D4sdi) man page) is called.

• In the start(D2sdi) routine, call the sdi_register(D3sdi) function. sdi_register( ) fails if there are no devices on the bus. On an HBA driver that has HBA_MP set, it is not an error for sdi_register( ) to return 0 devices found. The HBA driver must not interpret this as an error.

• Four additional SDI subfunctions need to be provided in the icmd(D2sdi) entry point routine:

  
  SFB_PAUSE

  stops all bus activity and may not return until all pending SDI functions have completed.

  
  SFB_CONTINUE

  continues all bus activity that had been stopped by an SFB_PAUSE.

  
  SFB_RM_DEV

  removes or invalidates any data structures associated with the device specified in the sfb(D4sdi) structure. This function should fail if the address is invalid, there is no device, or there are any pending jobs on the controller.

  
  SFB_ADD_DEV

  adds or validates any data structures associated with the device specified in the sfb(D4sdi) structure. This function should fail if the address is invalid or there already is a device at this address.

Coding in target drivers

To support device hot add/remove, a target driver needs to include the following code:

• Call the sdi_target_hotregister(D3sdi) routine from the target driver's rinit(D2sdi) entry point routine.

• Call the rm_dev(D2sdi) entry point to prepare a device for removal from the system. This usually entails flushing any cache on the device, and possibly spinning down or unmounting the device.

Administrative interface

The administrative interface for SDI hot add/remove is provided in two commands:

sdiadd(1M)

add new SDI peripheral device to the kernel.

sdirm(1M)

remove SDI peripheral device from the kernel.

Design limitations

Note the following limitations when using the SDI hot add/remove feature:

• Hot add/remove works only if both the target and HBA driver implement it.

• The device must not be opened by any user-level process.

• The SDI bus termination must not be altered.

• The hba_info(D4sdi) structure for the HBA must set the HBA_HOT flag.