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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.gz
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
1 files changed, 85 insertions, 0 deletions
diff --git a/Documentation/scsi/cxgb3i.txt b/Documentation/scsi/cxgb3i.txt
new file mode 100644
index 000000000000..8141fa01978e
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+++ b/Documentation/scsi/cxgb3i.txt
@@ -0,0 +1,85 @@
+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.