summaryrefslogtreecommitdiffstats
path: root/Documentation/scsi/scsi_fc_transport.txt
diff options
context:
space:
mode:
Diffstat (limited to 'Documentation/scsi/scsi_fc_transport.txt')
-rw-r--r--Documentation/scsi/scsi_fc_transport.txt496
1 files changed, 0 insertions, 496 deletions
diff --git a/Documentation/scsi/scsi_fc_transport.txt b/Documentation/scsi/scsi_fc_transport.txt
deleted file mode 100644
index f79282f..0000000
--- a/Documentation/scsi/scsi_fc_transport.txt
+++ /dev/null
@@ -1,496 +0,0 @@
- SCSI FC Tansport
- =============================================
-
-Date: 11/18/2008
-Kernel Revisions for features:
- rports : <<TBS>>
- vports : 2.6.22
- bsg support : 2.6.30 (?TBD?)
-
-
-Introduction
-============
-This file documents the features and components of the SCSI FC Transport.
-It also provides documents the API between the transport and FC LLDDs.
-The FC transport can be found at:
- drivers/scsi/scsi_transport_fc.c
- include/scsi/scsi_transport_fc.h
- include/scsi/scsi_netlink_fc.h
- include/scsi/scsi_bsg_fc.h
-
-This file is found at Documentation/scsi/scsi_fc_transport.txt
-
-
-FC Remote Ports (rports)
-========================================================================
-<< To Be Supplied >>
-
-
-FC Virtual Ports (vports)
-========================================================================
-
-Overview:
--------------------------------
-
- New FC standards have defined mechanisms which allows for a single physical
- port to appear on as multiple communication ports. Using the N_Port Id
- Virtualization (NPIV) mechanism, a point-to-point connection to a Fabric
- can be assigned more than 1 N_Port_ID. Each N_Port_ID appears as a
- separate port to other endpoints on the fabric, even though it shares one
- physical link to the switch for communication. Each N_Port_ID can have a
- unique view of the fabric based on fabric zoning and array lun-masking
- (just like a normal non-NPIV adapter). Using the Virtual Fabric (VF)
- mechanism, adding a fabric header to each frame allows the port to
- interact with the Fabric Port to join multiple fabrics. The port will
- obtain an N_Port_ID on each fabric it joins. Each fabric will have its
- own unique view of endpoints and configuration parameters. NPIV may be
- used together with VF so that the port can obtain multiple N_Port_IDs
- on each virtual fabric.
-
- The FC transport is now recognizing a new object - a vport. A vport is
- an entity that has a world-wide unique World Wide Port Name (wwpn) and
- World Wide Node Name (wwnn). The transport also allows for the FC4's to
- be specified for the vport, with FCP_Initiator being the primary role
- expected. Once instantiated by one of the above methods, it will have a
- distinct N_Port_ID and view of fabric endpoints and storage entities.
- The fc_host associated with the physical adapter will export the ability
- to create vports. The transport will create the vport object within the
- Linux device tree, and instruct the fc_host's driver to instantiate the
- virtual port. Typically, the driver will create a new scsi_host instance
- on the vport, resulting in a unique <H,C,T,L> namespace for the vport.
- Thus, whether a FC port is based on a physical port or on a virtual port,
- each will appear as a unique scsi_host with its own target and lun space.
-
- Note: At this time, the transport is written to create only NPIV-based
- vports. However, consideration was given to VF-based vports and it
- should be a minor change to add support if needed. The remaining
- discussion will concentrate on NPIV.
-
- Note: World Wide Name assignment (and uniqueness guarantees) are left
- up to an administrative entity controlling the vport. For example,
- if vports are to be associated with virtual machines, a XEN mgmt
- utility would be responsible for creating wwpn/wwnn's for the vport,
- using its own naming authority and OUI. (Note: it already does this
- for virtual MAC addresses).
-
-
-Device Trees and Vport Objects:
--------------------------------
-
- Today, the device tree typically contains the scsi_host object,
- with rports and scsi target objects underneath it. Currently the FC
- transport creates the vport object and places it under the scsi_host
- object corresponding to the physical adapter. The LLDD will allocate
- a new scsi_host for the vport and link its object under the vport.
- The remainder of the tree under the vports scsi_host is the same
- as the non-NPIV case. The transport is written currently to easily
- allow the parent of the vport to be something other than the scsi_host.
- This could be used in the future to link the object onto a vm-specific
- device tree. If the vport's parent is not the physical port's scsi_host,
- a symbolic link to the vport object will be placed in the physical
- port's scsi_host.
-
- Here's what to expect in the device tree :
- The typical Physical Port's Scsi_Host:
- /sys/devices/.../host17/
- and it has the typical descendant tree:
- /sys/devices/.../host17/rport-17:0-0/target17:0:0/17:0:0:0:
- and then the vport is created on the Physical Port:
- /sys/devices/.../host17/vport-17:0-0
- and the vport's Scsi_Host is then created:
- /sys/devices/.../host17/vport-17:0-0/host18
- and then the rest of the tree progresses, such as:
- /sys/devices/.../host17/vport-17:0-0/host18/rport-18:0-0/target18:0:0/18:0:0:0:
-
- Here's what to expect in the sysfs tree :
- scsi_hosts:
- /sys/class/scsi_host/host17 physical port's scsi_host
- /sys/class/scsi_host/host18 vport's scsi_host
- fc_hosts:
- /sys/class/fc_host/host17 physical port's fc_host
- /sys/class/fc_host/host18 vport's fc_host
- fc_vports:
- /sys/class/fc_vports/vport-17:0-0 the vport's fc_vport
- fc_rports:
- /sys/class/fc_remote_ports/rport-17:0-0 rport on the physical port
- /sys/class/fc_remote_ports/rport-18:0-0 rport on the vport
-
-
-Vport Attributes:
--------------------------------
-
- The new fc_vport class object has the following attributes
-
- node_name: Read_Only
- The WWNN of the vport
-
- port_name: Read_Only
- The WWPN of the vport
-
- roles: Read_Only
- Indicates the FC4 roles enabled on the vport.
-
- symbolic_name: Read_Write
- A string, appended to the driver's symbolic port name string, which
- is registered with the switch to identify the vport. For example,
- a hypervisor could set this string to "Xen Domain 2 VM 5 Vport 2",
- and this set of identifiers can be seen on switch management screens
- to identify the port.
-
- vport_delete: Write_Only
- When written with a "1", will tear down the vport.
-
- vport_disable: Write_Only
- When written with a "1", will transition the vport to a disabled.
- state. The vport will still be instantiated with the Linux kernel,
- but it will not be active on the FC link.
- When written with a "0", will enable the vport.
-
- vport_last_state: Read_Only
- Indicates the previous state of the vport. See the section below on
- "Vport States".
-
- vport_state: Read_Only
- Indicates the state of the vport. See the section below on
- "Vport States".
-
- vport_type: Read_Only
- Reflects the FC mechanism used to create the virtual port.
- Only NPIV is supported currently.
-
-
- For the fc_host class object, the following attributes are added for vports:
-
- max_npiv_vports: Read_Only
- Indicates the maximum number of NPIV-based vports that the
- driver/adapter can support on the fc_host.
-
- npiv_vports_inuse: Read_Only
- Indicates how many NPIV-based vports have been instantiated on the
- fc_host.
-
- vport_create: Write_Only
- A "simple" create interface to instantiate a vport on an fc_host.
- A "<WWPN>:<WWNN>" string is written to the attribute. The transport
- then instantiates the vport object and calls the LLDD to create the
- vport with the role of FCP_Initiator. Each WWN is specified as 16
- hex characters and may *not* contain any prefixes (e.g. 0x, x, etc).
-
- vport_delete: Write_Only
- A "simple" delete interface to teardown a vport. A "<WWPN>:<WWNN>"
- string is written to the attribute. The transport will locate the
- vport on the fc_host with the same WWNs and tear it down. Each WWN
- is specified as 16 hex characters and may *not* contain any prefixes
- (e.g. 0x, x, etc).
-
-
-Vport States:
--------------------------------
-
- Vport instantiation consists of two parts:
- - Creation with the kernel and LLDD. This means all transport and
- driver data structures are built up, and device objects created.
- This is equivalent to a driver "attach" on an adapter, which is
- independent of the adapter's link state.
- - Instantiation of the vport on the FC link via ELS traffic, etc.
- This is equivalent to a "link up" and successful link initialization.
- Further information can be found in the interfaces section below for
- Vport Creation.
-
- Once a vport has been instantiated with the kernel/LLDD, a vport state
- can be reported via the sysfs attribute. The following states exist:
-
- FC_VPORT_UNKNOWN - Unknown
- An temporary state, typically set only while the vport is being
- instantiated with the kernel and LLDD.
-
- FC_VPORT_ACTIVE - Active
- The vport has been successfully been created on the FC link.
- It is fully functional.
-
- FC_VPORT_DISABLED - Disabled
- The vport instantiated, but "disabled". The vport is not instantiated
- on the FC link. This is equivalent to a physical port with the
- link "down".
-
- FC_VPORT_LINKDOWN - Linkdown
- The vport is not operational as the physical link is not operational.
-
- FC_VPORT_INITIALIZING - Initializing
- The vport is in the process of instantiating on the FC link.
- The LLDD will set this state just prior to starting the ELS traffic
- to create the vport. This state will persist until the vport is
- successfully created (state becomes FC_VPORT_ACTIVE) or it fails
- (state is one of the values below). As this state is transitory,
- it will not be preserved in the "vport_last_state".
-
- FC_VPORT_NO_FABRIC_SUPP - No Fabric Support
- The vport is not operational. One of the following conditions were
- encountered:
- - The FC topology is not Point-to-Point
- - The FC port is not connected to an F_Port
- - The F_Port has indicated that NPIV is not supported.
-
- FC_VPORT_NO_FABRIC_RSCS - No Fabric Resources
- The vport is not operational. The Fabric failed FDISC with a status
- indicating that it does not have sufficient resources to complete
- the operation.
-
- FC_VPORT_FABRIC_LOGOUT - Fabric Logout
- The vport is not operational. The Fabric has LOGO'd the N_Port_ID
- associated with the vport.
-
- FC_VPORT_FABRIC_REJ_WWN - Fabric Rejected WWN
- The vport is not operational. The Fabric failed FDISC with a status
- indicating that the WWN's are not valid.
-
- FC_VPORT_FAILED - VPort Failed
- The vport is not operational. This is a catchall for all other
- error conditions.
-
-
- The following state table indicates the different state transitions:
-
- State Event New State
- --------------------------------------------------------------------
- n/a Initialization Unknown
- Unknown: Link Down Linkdown
- Link Up & Loop No Fabric Support
- Link Up & no Fabric No Fabric Support
- Link Up & FLOGI response No Fabric Support
- indicates no NPIV support
- Link Up & FDISC being sent Initializing
- Disable request Disable
- Linkdown: Link Up Unknown
- Initializing: FDISC ACC Active
- FDISC LS_RJT w/ no resources No Fabric Resources
- FDISC LS_RJT w/ invalid Fabric Rejected WWN
- pname or invalid nport_id
- FDISC LS_RJT failed for Vport Failed
- other reasons
- Link Down Linkdown
- Disable request Disable
- Disable: Enable request Unknown
- Active: LOGO received from fabric Fabric Logout
- Link Down Linkdown
- Disable request Disable
- Fabric Logout: Link still up Unknown
-
- The following 4 error states all have the same transitions:
- No Fabric Support:
- No Fabric Resources:
- Fabric Rejected WWN:
- Vport Failed:
- Disable request Disable
- Link goes down Linkdown
-
-
-Transport <-> LLDD Interfaces :
--------------------------------
-
-Vport support by LLDD:
-
- The LLDD indicates support for vports by supplying a vport_create()
- function in the transport template. The presence of this function will
- cause the creation of the new attributes on the fc_host. As part of
- the physical port completing its initialization relative to the
- transport, it should set the max_npiv_vports attribute to indicate the
- maximum number of vports the driver and/or adapter supports.
-
-
-Vport Creation:
-
- The LLDD vport_create() syntax is:
-
- int vport_create(struct fc_vport *vport, bool disable)
-
- where:
- vport: Is the newly allocated vport object
- disable: If "true", the vport is to be created in a disabled stated.
- If "false", the vport is to be enabled upon creation.
-
- When a request is made to create a new vport (via sgio/netlink, or the
- vport_create fc_host attribute), the transport will validate that the LLDD
- can support another vport (e.g. max_npiv_vports > npiv_vports_inuse).
- If not, the create request will be failed. If space remains, the transport
- will increment the vport count, create the vport object, and then call the
- LLDD's vport_create() function with the newly allocated vport object.
-
- As mentioned above, vport creation is divided into two parts:
- - Creation with the kernel and LLDD. This means all transport and
- driver data structures are built up, and device objects created.
- This is equivalent to a driver "attach" on an adapter, which is
- independent of the adapter's link state.
- - Instantiation of the vport on the FC link via ELS traffic, etc.
- This is equivalent to a "link up" and successful link initialization.
-
- The LLDD's vport_create() function will not synchronously wait for both
- parts to be fully completed before returning. It must validate that the
- infrastructure exists to support NPIV, and complete the first part of
- vport creation (data structure build up) before returning. We do not
- hinge vport_create() on the link-side operation mainly because:
- - The link may be down. It is not a failure if it is. It simply
- means the vport is in an inoperable state until the link comes up.
- This is consistent with the link bouncing post vport creation.
- - The vport may be created in a disabled state.
- - This is consistent with a model where: the vport equates to a
- FC adapter. The vport_create is synonymous with driver attachment
- to the adapter, which is independent of link state.
-
- Note: special error codes have been defined to delineate infrastructure
- failure cases for quicker resolution.
-
- The expected behavior for the LLDD's vport_create() function is:
- - Validate Infrastructure:
- - If the driver or adapter cannot support another vport, whether
- due to improper firmware, (a lie about) max_npiv, or a lack of
- some other resource - return VPCERR_UNSUPPORTED.
- - If the driver validates the WWN's against those already active on
- the adapter and detects an overlap - return VPCERR_BAD_WWN.
- - If the driver detects the topology is loop, non-fabric, or the
- FLOGI did not support NPIV - return VPCERR_NO_FABRIC_SUPP.
- - Allocate data structures. If errors are encountered, such as out
- of memory conditions, return the respective negative Exxx error code.
- - If the role is FCP Initiator, the LLDD is to :
- - Call scsi_host_alloc() to allocate a scsi_host for the vport.
- - Call scsi_add_host(new_shost, &vport->dev) to start the scsi_host
- and bind it as a child of the vport device.
- - Initializes the fc_host attribute values.
- - Kick of further vport state transitions based on the disable flag and
- link state - and return success (zero).
-
- LLDD Implementers Notes:
- - It is suggested that there be a different fc_function_templates for
- the physical port and the virtual port. The physical port's template
- would have the vport_create, vport_delete, and vport_disable functions,
- while the vports would not.
- - It is suggested that there be different scsi_host_templates
- for the physical port and virtual port. Likely, there are driver
- attributes, embedded into the scsi_host_template, that are applicable
- for the physical port only (link speed, topology setting, etc). This
- ensures that the attributes are applicable to the respective scsi_host.
-
-
-Vport Disable/Enable:
-
- The LLDD vport_disable() syntax is:
-
- int vport_disable(struct fc_vport *vport, bool disable)
-
- where:
- vport: Is vport to be enabled or disabled
- disable: If "true", the vport is to be disabled.
- If "false", the vport is to be enabled.
-
- When a request is made to change the disabled state on a vport, the
- transport will validate the request against the existing vport state.
- If the request is to disable and the vport is already disabled, the
- request will fail. Similarly, if the request is to enable, and the
- vport is not in a disabled state, the request will fail. If the request
- is valid for the vport state, the transport will call the LLDD to
- change the vport's state.
-
- Within the LLDD, if a vport is disabled, it remains instantiated with
- the kernel and LLDD, but it is not active or visible on the FC link in
- any way. (see Vport Creation and the 2 part instantiation discussion).
- The vport will remain in this state until it is deleted or re-enabled.
- When enabling a vport, the LLDD reinstantiates the vport on the FC
- link - essentially restarting the LLDD statemachine (see Vport States
- above).
-
-
-Vport Deletion:
-
- The LLDD vport_delete() syntax is:
-
- int vport_delete(struct fc_vport *vport)
-
- where:
- vport: Is vport to delete
-
- When a request is made to delete a vport (via sgio/netlink, or via the
- fc_host or fc_vport vport_delete attributes), the transport will call
- the LLDD to terminate the vport on the FC link, and teardown all other
- datastructures and references. If the LLDD completes successfully,
- the transport will teardown the vport objects and complete the vport
- removal. If the LLDD delete request fails, the vport object will remain,
- but will be in an indeterminate state.
-
- Within the LLDD, the normal code paths for a scsi_host teardown should
- be followed. E.g. If the vport has a FCP Initiator role, the LLDD
- will call fc_remove_host() for the vports scsi_host, followed by
- scsi_remove_host() and scsi_host_put() for the vports scsi_host.
-
-
-Other:
- fc_host port_type attribute:
- There is a new fc_host port_type value - FC_PORTTYPE_NPIV. This value
- must be set on all vport-based fc_hosts. Normally, on a physical port,
- the port_type attribute would be set to NPORT, NLPORT, etc based on the
- topology type and existence of the fabric. As this is not applicable to
- a vport, it makes more sense to report the FC mechanism used to create
- the vport.
-
- Driver unload:
- FC drivers are required to call fc_remove_host() prior to calling
- scsi_remove_host(). This allows the fc_host to tear down all remote
- ports prior the scsi_host being torn down. The fc_remove_host() call
- was updated to remove all vports for the fc_host as well.
-
-
-Transport supplied functions
-----------------------------
-
-The following functions are supplied by the FC-transport for use by LLDs.
-
- fc_vport_create - create a vport
- fc_vport_terminate - detach and remove a vport
-
-Details:
-
-/**
- * fc_vport_create - Admin App or LLDD requests creation of a vport
- * @shost: scsi host the virtual port is connected to.
- * @ids: The world wide names, FC4 port roles, etc for
- * the virtual port.
- *
- * Notes:
- * This routine assumes no locks are held on entry.
- */
-struct fc_vport *
-fc_vport_create(struct Scsi_Host *shost, struct fc_vport_identifiers *ids)
-
-/**
- * fc_vport_terminate - Admin App or LLDD requests termination of a vport
- * @vport: fc_vport to be terminated
- *
- * Calls the LLDD vport_delete() function, then deallocates and removes
- * the vport from the shost and object tree.
- *
- * Notes:
- * This routine assumes no locks are held on entry.
- */
-int
-fc_vport_terminate(struct fc_vport *vport)
-
-
-FC BSG support (CT & ELS passthru, and more)
-========================================================================
-<< To Be Supplied >>
-
-
-
-
-
-Credits
-=======
-The following people have contributed to this document:
-
-
-
-
-
-
-James Smart
-james.smart@emulex.com
-