diff options
author | Linus Torvalds <torvalds@linux-foundation.org> | 2008-12-30 20:43:10 -0500 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-12-30 20:43:10 -0500 |
commit | 590cf28580c999c8ba70dc39b40bab09d69e2630 (patch) | |
tree | 22b9aa4b148bea8a310b760521d1032eef7d743f /Documentation | |
parent | f54a6ec0fd85002d94d05b4bb679508eeb066683 (diff) | |
parent | fb5edd020fa0fbe991f4a473611ad530d2237425 (diff) |
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.txt | 85 |
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 --- /dev/null +++ b/Documentation/scsi/cxgb3i.txt | |||
@@ -0,0 +1,85 @@ | |||
1 | Chelsio S3 iSCSI Driver for Linux | ||
2 | |||
3 | Introduction | ||
4 | ============ | ||
5 | |||
6 | The Chelsio T3 ASIC based Adapters (S310, S320, S302, S304, Mezz cards, etc. | ||
7 | series of products) supports iSCSI acceleration and iSCSI Direct Data Placement | ||
8 | (DDP) where the hardware handles the expensive byte touching operations, such | ||
9 | as CRC computation and verification, and direct DMA to the final host memory | ||
10 | destination: | ||
11 | |||
12 | - iSCSI PDU digest generation and verification | ||
13 | |||
14 | On transmitting, Chelsio S3 h/w computes and inserts the Header and | ||
15 | Data digest into the PDUs. | ||
16 | On receiving, Chelsio S3 h/w computes and verifies the Header and | ||
17 | Data digest of the PDUs. | ||
18 | |||
19 | - Direct Data Placement (DDP) | ||
20 | |||
21 | S3 h/w can directly place the iSCSI Data-In or Data-Out PDU's | ||
22 | payload into pre-posted final destination host-memory buffers based | ||
23 | on the Initiator Task Tag (ITT) in Data-In or Target Task Tag (TTT) | ||
24 | in Data-Out PDUs. | ||
25 | |||
26 | - PDU Transmit and Recovery | ||
27 | |||
28 | On transmitting, S3 h/w accepts the complete PDU (header + data) | ||
29 | from the host driver, computes and inserts the digests, decomposes | ||
30 | the PDU into multiple TCP segments if necessary, and transmit all | ||
31 | the TCP segments onto the wire. It handles TCP retransmission if | ||
32 | needed. | ||
33 | |||
34 | On receving, S3 h/w recovers the iSCSI PDU by reassembling TCP | ||
35 | segments, separating the header and data, calculating and verifying | ||
36 | the digests, then forwards the header to the host. The payload data, | ||
37 | if possible, will be directly placed into the pre-posted host DDP | ||
38 | buffer. Otherwise, the payload data will be sent to the host too. | ||
39 | |||
40 | The cxgb3i driver interfaces with open-iscsi initiator and provides the iSCSI | ||
41 | acceleration through Chelsio hardware wherever applicable. | ||
42 | |||
43 | Using the cxgb3i Driver | ||
44 | ======================= | ||
45 | |||
46 | The following steps need to be taken to accelerates the open-iscsi initiator: | ||
47 | |||
48 | 1. Load the cxgb3i driver: "modprobe cxgb3i" | ||
49 | |||
50 | The cxgb3i module registers a new transport class "cxgb3i" with open-iscsi. | ||
51 | |||
52 | * in the case of recompiling the kernel, the cxgb3i selection is located at | ||
53 | Device Drivers | ||
54 | SCSI device support ---> | ||
55 | [*] SCSI low-level drivers ---> | ||
56 | <M> Chelsio S3xx iSCSI support | ||
57 | |||
58 | 2. Create an interface file located under /etc/iscsi/ifaces/ for the new | ||
59 | transport class "cxgb3i". | ||
60 | |||
61 | The content of the file should be in the following format: | ||
62 | iface.transport_name = cxgb3i | ||
63 | iface.net_ifacename = <ethX> | ||
64 | iface.ipaddress = <iscsi ip address> | ||
65 | |||
66 | * if iface.ipaddress is specified, <iscsi ip address> needs to be either the | ||
67 | same as the ethX's ip address or an address on the same subnet. Make | ||
68 | sure the ip address is unique in the network. | ||
69 | |||
70 | 3. edit /etc/iscsi/iscsid.conf | ||
71 | The default setting for MaxRecvDataSegmentLength (131072) is too big, | ||
72 | replace "node.conn[0].iscsi.MaxRecvDataSegmentLength" to be a value no | ||
73 | bigger than 15360 (for example 8192): | ||
74 | |||
75 | node.conn[0].iscsi.MaxRecvDataSegmentLength = 8192 | ||
76 | |||
77 | * The login would fail for a normal session if MaxRecvDataSegmentLength is | ||
78 | too big. A error message in the format of | ||
79 | "cxgb3i: ERR! MaxRecvSegmentLength <X> too big. Need to be <= <Y>." | ||
80 | would be logged to dmesg. | ||
81 | |||
82 | 4. To direct open-iscsi traffic to go through cxgb3i's accelerated path, | ||
83 | "-I <iface file name>" option needs to be specified with most of the | ||
84 | iscsiadm command. <iface file name> is the transport interface file created | ||
85 | in step 2. | ||