1 .. SPDX-License-Identifier: GPL-2.0
2
3 =================================
4 Chelsio S3 iSCSI Driver for Linux
5 =================================
6
7 Introduction
8 ============
9
10 The Chelsio T3 ASIC based Adapters (S310, S320
11 series of products) support iSCSI acceleration
12 (DDP) where the hardware handles the expensive
13 as CRC computation and verification, and direc
14 destination:
15
16 - iSCSI PDU digest generation and veri
17
18 On transmitting, Chelsio S3 h/w comp
19 Data digest into the PDUs.
20 On receiving, Chelsio S3 h/w compute
21 Data digest of the PDUs.
22
23 - Direct Data Placement (DDP)
24
25 S3 h/w can directly place the iSCSI
26 payload into pre-posted final destin
27 on the Initiator Task Tag (ITT) in D
28 in Data-Out PDUs.
29
30 - PDU Transmit and Recovery
31
32 On transmitting, S3 h/w accepts the
33 from the host driver, computes and i
34 the PDU into multiple TCP segments i
35 the TCP segments onto the wire. It h
36 needed.
37
38 On receiving, S3 h/w recovers the iS
39 segments, separating the header and
40 the digests, then forwarding the hea
41 if possible, will be directly placed
42 buffer. Otherwise, the payload data
43
44 The cxgb3i driver interfaces with open-iscsi i
45 acceleration through Chelsio hardware wherever
46
47 Using the cxgb3i Driver
48 =======================
49
50 The following steps need to be taken to accele
51
52 1. Load the cxgb3i driver: "modprobe cxgb3i"
53
54 The cxgb3i module registers a new transport
55
56 * in the case of recompiling the kernel, th
57
58 Device Drivers
59 SCSI device support --->
60 [*] SCSI low-level dri
61 <M> Chelsio
62
63 2. Create an interface file located under /etc
64 transport class "cxgb3i".
65
66 The content of the file should be in the fo
67
68 iface.transport_name = cxgb3i
69 iface.net_ifacename = <ethX>
70 iface.ipaddress = <iscsi ip address>
71
72 * if iface.ipaddress is specified, <iscsi i
73 same as the ethX's ip address or an addre
74 sure the ip address is unique in the netw
75
76 3. edit /etc/iscsi/iscsid.conf
77 The default setting for MaxRecvDataSegmentL
78 replace with a value no bigger than 15360 (
79
80 node.conn[0].iscsi.MaxRecvDataSegmentL
81
82 * The login would fail for a normal session
83 too big. A error message in the format o
84 "cxgb3i: ERR! MaxRecvSegmentLength <X> to
85 would be logged to dmesg.
86
87 4. To direct open-iscsi traffic to go through
88 "-I <iface file name>" option needs to be s
89 iscsiadm command. <iface file name> is the
90 in step 2.
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