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authorLinus Torvalds <torvalds@linux-foundation.org>2008-12-30 17:43:10 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2008-12-30 17:43:10 -0800
commit590cf28580c999c8ba70dc39b40bab09d69e2630 (patch)
tree22b9aa4b148bea8a310b760521d1032eef7d743f /Documentation
parentf54a6ec0fd85002d94d05b4bb679508eeb066683 (diff)
parentfb5edd020fa0fbe991f4a473611ad530d2237425 (diff)
downloadlinux-590cf28580c999c8ba70dc39b40bab09d69e2630.tar.bz2
Merge git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi-misc-2.6
* git://git.kernel.org/pub/scm/linux/kernel/git/jejb/scsi-misc-2.6: (104 commits) [SCSI] fcoe: fix configuration problems [SCSI] cxgb3i: fix select/depend problem [SCSI] fcoe: fix incorrect use of struct module [SCSI] cxgb3i: remove use of skb->sp [SCSI] cxgb3i: Add cxgb3i iSCSI driver. [SCSI] zfcp: Remove unnecessary warning message [SCSI] zfcp: Add support for unchained FSF requests [SCSI] zfcp: Remove busid macro [SCSI] zfcp: remove DID_DID flag [SCSI] zfcp: Simplify mask lookups for incoming RSCNs [SCSI] zfcp: Remove initial device data from zfcp_data [SCSI] zfcp: fix compile warning [SCSI] zfcp: Remove adapter list [SCSI] zfcp: Simplify SBAL allocation to fix sparse warnings [SCSI] zfcp: register with SCSI layer on ccw registration [SCSI] zfcp: Fix message line break [SCSI] qla2xxx: changes in multiq code [SCSI] eata: fix the data buffer accessors conversion regression [SCSI] ibmvfc: Improve async event handling [SCSI] lpfc : correct printk types on PPC compiles ...
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/scsi/cxgb3i.txt85
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diff --git a/Documentation/scsi/cxgb3i.txt b/Documentation/scsi/cxgb3i.txt
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+Chelsio S3 iSCSI Driver for Linux
+
+Introduction
+============
+
+The Chelsio T3 ASIC based Adapters (S310, S320, S302, S304, Mezz cards, etc.
+series of products) supports iSCSI acceleration and iSCSI Direct Data Placement
+(DDP) where the hardware handles the expensive byte touching operations, such
+as CRC computation and verification, and direct DMA to the final host memory
+destination:
+
+ - iSCSI PDU digest generation and verification
+
+ On transmitting, Chelsio S3 h/w computes and inserts the Header and
+ Data digest into the PDUs.
+ On receiving, Chelsio S3 h/w computes and verifies the Header and
+ Data digest of the PDUs.
+
+ - Direct Data Placement (DDP)
+
+ S3 h/w can directly place the iSCSI Data-In or Data-Out PDU's
+ payload into pre-posted final destination host-memory buffers based
+ on the Initiator Task Tag (ITT) in Data-In or Target Task Tag (TTT)
+ in Data-Out PDUs.
+
+ - PDU Transmit and Recovery
+
+ On transmitting, S3 h/w accepts the complete PDU (header + data)
+ from the host driver, computes and inserts the digests, decomposes
+ the PDU into multiple TCP segments if necessary, and transmit all
+ the TCP segments onto the wire. It handles TCP retransmission if
+ needed.
+
+ On receving, S3 h/w recovers the iSCSI PDU by reassembling TCP
+ segments, separating the header and data, calculating and verifying
+ the digests, then forwards the header to the host. The payload data,
+ if possible, will be directly placed into the pre-posted host DDP
+ buffer. Otherwise, the payload data will be sent to the host too.
+
+The cxgb3i driver interfaces with open-iscsi initiator and provides the iSCSI
+acceleration through Chelsio hardware wherever applicable.
+
+Using the cxgb3i Driver
+=======================
+
+The following steps need to be taken to accelerates the open-iscsi initiator:
+
+1. Load the cxgb3i driver: "modprobe cxgb3i"
+
+ The cxgb3i module registers a new transport class "cxgb3i" with open-iscsi.
+
+ * in the case of recompiling the kernel, the cxgb3i selection is located at
+ Device Drivers
+ SCSI device support --->
+ [*] SCSI low-level drivers --->
+ <M> Chelsio S3xx iSCSI support
+
+2. Create an interface file located under /etc/iscsi/ifaces/ for the new
+ transport class "cxgb3i".
+
+ The content of the file should be in the following format:
+ iface.transport_name = cxgb3i
+ iface.net_ifacename = <ethX>
+ iface.ipaddress = <iscsi ip address>
+
+ * if iface.ipaddress is specified, <iscsi ip address> needs to be either the
+ same as the ethX's ip address or an address on the same subnet. Make
+ sure the ip address is unique in the network.
+
+3. edit /etc/iscsi/iscsid.conf
+ The default setting for MaxRecvDataSegmentLength (131072) is too big,
+ replace "node.conn[0].iscsi.MaxRecvDataSegmentLength" to be a value no
+ bigger than 15360 (for example 8192):
+
+ node.conn[0].iscsi.MaxRecvDataSegmentLength = 8192
+
+ * The login would fail for a normal session if MaxRecvDataSegmentLength is
+ too big. A error message in the format of
+ "cxgb3i: ERR! MaxRecvSegmentLength <X> too big. Need to be <= <Y>."
+ would be logged to dmesg.
+
+4. To direct open-iscsi traffic to go through cxgb3i's accelerated path,
+ "-I <iface file name>" option needs to be specified with most of the
+ iscsiadm command. <iface file name> is the transport interface file created
+ in step 2.