1 files changed, 352 insertions, 0 deletions

diff --git a/Documentation/networking/cxgb.txt b/Documentation/networking/cxgb.txt
new file mode 100644
index 000000000000..76324638626b
--- /dev/null
+++ b/Documentation/networking/cxgb.txt
@@ -0,0 +1,352 @@
+                 Chelsio N210 10Gb Ethernet Network Controller
+
+                         Driver Release Notes for Linux
+
+                                 Version 2.1.1
+
+                                 June 20, 2005
+
+CONTENTS
+========
+ INTRODUCTION
+ FEATURES
+ PERFORMANCE
+ DRIVER MESSAGES
+ KNOWN ISSUES
+ SUPPORT
+
+
+INTRODUCTION
+============
+
+ This document describes the Linux driver for Chelsio 10Gb Ethernet Network
+ Controller. This driver supports the Chelsio N210 NIC and is backward
+ compatible with the Chelsio N110 model 10Gb NICs.
+
+
+FEATURES
+========
+
+ Adaptive Interrupts (adaptive-rx)
+ ---------------------------------
+
+  This feature provides an adaptive algorithm that adjusts the interrupt
+  coalescing parameters, allowing the driver to dynamically adapt the latency
+  settings to achieve the highest performance during various types of network
+  load.
+
+  The interface used to control this feature is ethtool. Please see the
+  ethtool manpage for additional usage information.
+
+  By default, adaptive-rx is disabled.
+  To enable adaptive-rx:
+
+      ethtool -C <interface> adaptive-rx on
+
+  To disable adaptive-rx, use ethtool:
+
+      ethtool -C <interface> adaptive-rx off
+
+  After disabling adaptive-rx, the timer latency value will be set to 50us.
+  You may set the timer latency after disabling adaptive-rx:
+
+      ethtool -C <interface> rx-usecs <microseconds>
+
+  An example to set the timer latency value to 100us on eth0:
+
+      ethtool -C eth0 rx-usecs 100
+
+  You may also provide a timer latency value while disabling adpative-rx:
+
+      ethtool -C <interface> adaptive-rx off rx-usecs <microseconds>
+
+  If adaptive-rx is disabled and a timer latency value is specified, the timer
+  will be set to the specified value until changed by the user or until
+  adaptive-rx is enabled.
+
+  To view the status of the adaptive-rx and timer latency values:
+
+      ethtool -c <interface>
+
+
+ TCP Segmentation Offloading (TSO) Support
+ -----------------------------------------
+
+  This feature, also known as "large send", enables a system's protocol stack
+  to offload portions of outbound TCP processing to a network interface card
+  thereby reducing system CPU utilization and enhancing performance.
+
+  The interface used to control this feature is ethtool version 1.8 or higher.
+  Please see the ethtool manpage for additional usage information.
+
+  By default, TSO is enabled.
+  To disable TSO:
+
+      ethtool -K <interface> tso off
+
+  To enable TSO:
+
+      ethtool -K <interface> tso on
+
+  To view the status of TSO:
+
+      ethtool -k <interface>
+
+
+PERFORMANCE
+===========
+
+ The following information is provided as an example of how to change system
+ parameters for "performance tuning" an what value to use. You may or may not
+ want to change these system parameters, depending on your server/workstation
+ application. Doing so is not warranted in any way by Chelsio Communications,
+ and is done at "YOUR OWN RISK". Chelsio will not be held responsible for loss
+ of data or damage to equipment.
+
+ Your distribution may have a different way of doing things, or you may prefer
+ a different method. These commands are shown only to provide an example of
+ what to do and are by no means definitive.
+
+ Making any of the following system changes will only last until you reboot
+ your system. You may want to write a script that runs at boot-up which
+ includes the optimal settings for your system.
+
+  Setting PCI Latency Timer:
+      setpci -d 1425:* 0x0c.l=0x0000F800
+
+  Disabling TCP timestamp:
+      sysctl -w net.ipv4.tcp_timestamps=0
+
+  Disabling SACK:
+      sysctl -w net.ipv4.tcp_sack=0
+
+  Setting large number of incoming connection requests:
+      sysctl -w net.ipv4.tcp_max_syn_backlog=3000
+
+  Setting maximum receive socket buffer size:
+      sysctl -w net.core.rmem_max=1024000
+
+  Setting maximum send socket buffer size:
+      sysctl -w net.core.wmem_max=1024000
+
+  Set smp_affinity (on a multiprocessor system) to a single CPU:
+      echo 1 > /proc/irq/<interrupt_number>/smp_affinity
+
+  Setting default receive socket buffer size:
+      sysctl -w net.core.rmem_default=524287
+
+  Setting default send socket buffer size:
+      sysctl -w net.core.wmem_default=524287
+
+  Setting maximum option memory buffers:
+      sysctl -w net.core.optmem_max=524287
+
+  Setting maximum backlog (# of unprocessed packets before kernel drops):
+      sysctl -w net.core.netdev_max_backlog=300000
+
+  Setting TCP read buffers (min/default/max):
+      sysctl -w net.ipv4.tcp_rmem="10000000 10000000 10000000"
+
+  Setting TCP write buffers (min/pressure/max):
+      sysctl -w net.ipv4.tcp_wmem="10000000 10000000 10000000"
+
+  Setting TCP buffer space (min/pressure/max):
+      sysctl -w net.ipv4.tcp_mem="10000000 10000000 10000000"
+
+  TCP window size for single connections:
+   The receive buffer (RX_WINDOW) size must be at least as large as the
+   Bandwidth-Delay Product of the communication link between the sender and
+   receiver. Due to the variations of RTT, you may want to increase the buffer
+   size up to 2 times the Bandwidth-Delay Product. Reference page 289 of
+   "TCP/IP Illustrated, Volume 1, The Protocols" by W. Richard Stevens.
+   At 10Gb speeds, use the following formula:
+       RX_WINDOW >= 1.25MBytes * RTT(in milliseconds)
+       Example for RTT with 100us: RX_WINDOW = (1,250,000 * 0.1) = 125,000
+   RX_WINDOW sizes of 256KB - 512KB should be sufficient.
+   Setting the min, max, and default receive buffer (RX_WINDOW) size:
+       sysctl -w net.ipv4.tcp_rmem="<min> <default> <max>"
+
+  TCP window size for multiple connections:
+   The receive buffer (RX_WINDOW) size may be calculated the same as single
+   connections, but should be divided by the number of connections. The
+   smaller window prevents congestion and facilitates better pacing,
+   especially if/when MAC level flow control does not work well or when it is
+   not supported on the machine. Experimentation may be necessary to attain
+   the correct value. This method is provided as a starting point fot the
+   correct receive buffer size.
+   Setting the min, max, and default receive buffer (RX_WINDOW) size is
+   performed in the same manner as single connection.
+
+
+DRIVER MESSAGES
+===============
+
+ The following messages are the most common messages logged by syslog. These
+ may be found in /var/log/messages.
+
+  Driver up:
+     Chelsio Network Driver - version 2.1.1
+
+  NIC detected:
+     eth#: Chelsio N210 1x10GBaseX NIC (rev #), PCIX 133MHz/64-bit
+
+  Link up:
+     eth#: link is up at 10 Gbps, full duplex
+
+  Link down:
+     eth#: link is down
+
+
+KNOWN ISSUES
+============
+
+ These issues have been identified during testing. The following information
+ is provided as a workaround to the problem. In some cases, this problem is
+ inherent to Linux or to a particular Linux Distribution and/or hardware
+ platform.
+
+  1. Large number of TCP retransmits on a multiprocessor (SMP) system.
+
+      On a system with multiple CPUs, the interrupt (IRQ) for the network
+      controller may be bound to more than one CPU. This will cause TCP
+      retransmits if the packet data were to be split across different CPUs
+      and re-assembled in a different order than expected.
+
+      To eliminate the TCP retransmits, set smp_affinity on the particular
+      interrupt to a single CPU. You can locate the interrupt (IRQ) used on
+      the N110/N210 by using ifconfig:
+          ifconfig <dev_name> | grep Interrupt
+      Set the smp_affinity to a single CPU:
+          echo 1 > /proc/irq/<interrupt_number>/smp_affinity
+
+      It is highly suggested that you do not run the irqbalance daemon on your
+      system, as this will change any smp_affinity setting you have applied.
+      The irqbalance daemon runs on a 10 second interval and binds interrupts
+      to the least loaded CPU determined by the daemon. To disable this daemon:
+          chkconfig --level 2345 irqbalance off
+
+      By default, some Linux distributions enable the kernel feature,
+      irqbalance, which performs the same function as the daemon. To disable
+      this feature, add the following line to your bootloader:
+          noirqbalance
+
+          Example using the Grub bootloader:
+              title Red Hat Enterprise Linux AS (2.4.21-27.ELsmp)
+              root (hd0,0)
+              kernel /vmlinuz-2.4.21-27.ELsmp ro root=/dev/hda3 noirqbalance
+              initrd /initrd-2.4.21-27.ELsmp.img
+
+  2. After running insmod, the driver is loaded and the incorrect network
+     interface is brought up without running ifup.
+
+      When using 2.4.x kernels, including RHEL kernels, the Linux kernel
+      invokes a script named "hotplug". This script is primarily used to
+      automatically bring up USB devices when they are plugged in, however,
+      the script also attempts to automatically bring up a network interface
+      after loading the kernel module. The hotplug script does this by scanning
+      the ifcfg-eth# config files in /etc/sysconfig/network-scripts, looking
+      for HWADDR=<mac_address>.
+
+      If the hotplug script does not find the HWADDRR within any of the
+      ifcfg-eth# files, it will bring up the device with the next available
+      interface name. If this interface is already configured for a different
+      network card, your new interface will have incorrect IP address and
+      network settings.
+
+      To solve this issue, you can add the HWADDR=<mac_address> key to the
+      interface config file of your network controller.
+
+      To disable this "hotplug" feature, you may add the driver (module name)
+      to the "blacklist" file located in /etc/hotplug. It has been noted that
+      this does not work for network devices because the net.agent script
+      does not use the blacklist file. Simply remove, or rename, the net.agent
+      script located in /etc/hotplug to disable this feature.
+
+  3. Transport Protocol (TP) hangs when running heavy multi-connection traffic
+     on an AMD Opteron system with HyperTransport PCI-X Tunnel chipset.
+
+      If your AMD Opteron system uses the AMD-8131 HyperTransport PCI-X Tunnel
+      chipset, you may experience the "133-Mhz Mode Split Completion Data
+      Corruption" bug identified by AMD while using a 133Mhz PCI-X card on the
+      bus PCI-X bus.
+
+      AMD states, "Under highly specific conditions, the AMD-8131 PCI-X Tunnel
+      can provide stale data via split completion cycles to a PCI-X card that
+      is operating at 133 Mhz", causing data corruption.
+
+      AMD's provides three workarounds for this problem, however, Chelsio
+      recommends the first option for best performance with this bug:
+
+        For 133Mhz secondary bus operation, limit the transaction length and
+        the number of outstanding transactions, via BIOS configuration
+        programming of the PCI-X card, to the following:
+
+           Data Length (bytes): 1k
+           Total allowed outstanding transactions: 2
+
+      Please refer to AMD 8131-HT/PCI-X Errata 26310 Rev 3.08 August 2004,
+      section 56, "133-MHz Mode Split Completion Data Corruption" for more
+      details with this bug and workarounds suggested by AMD.
+
+      It may be possible to work outside AMD's recommended PCI-X settings, try
+      increasing the Data Length to 2k bytes for increased performance. If you
+      have issues with these settings, please revert to the "safe" settings
+      and duplicate the problem before submitting a bug or asking for support.
+
+      NOTE: The default setting on most systems is 8 outstanding transactions
+            and 2k bytes data length.
+
+  4. On multiprocessor systems, it has been noted that an application which
+     is handling 10Gb networking can switch between CPUs causing degraded
+     and/or unstable performance.
+
+      If running on an SMP system and taking performance measurements, it
+      is suggested you either run the latest netperf-2.4.0+ or use a binding
+      tool such as Tim Hockin's procstate utilities (runon)
+      <http://www.hockin.org/~thockin/procstate/>.
+
+      Binding netserver and netperf (or other applications) to particular
+      CPUs will have a significant difference in performance measurements.
+      You may need to experiment which CPU to bind the application to in
+      order to achieve the best performance for your system.
+
+      If you are developing an application designed for 10Gb networking,
+      please keep in mind you may want to look at kernel functions
+      sched_setaffinity & sched_getaffinity to bind your application.
+
+      If you are just running user-space applications such as ftp, telnet,
+      etc., you may want to try the runon tool provided by Tim Hockin's
+      procstate utility. You could also try binding the interface to a
+      particular CPU: runon 0 ifup eth0
+
+
+SUPPORT
+=======
+
+ If you have problems with the software or hardware, please contact our
+ customer support team via email at support@chelsio.com or check our website
+ at http://www.chelsio.com
+
+===============================================================================
+
+ Chelsio Communications
+ 370 San Aleso Ave.
+ Suite 100
+ Sunnyvale, CA 94085
+ http://www.chelsio.com
+
+This program is free software; you can redistribute it and/or modify
+it under the terms of the GNU General Public License, version 2, as
+published by the Free Software Foundation.
+
+You should have received a copy of the GNU General Public License along
+with this program; if not, write to the Free Software Foundation, Inc.,
+59 Temple Place - Suite 330, Boston, MA  02111-1307, USA.
+
+THIS SOFTWARE IS PROVIDED ``AS IS'' AND WITHOUT ANY EXPRESS OR IMPLIED
+WARRANTIES, INCLUDING, WITHOUT LIMITATION, THE IMPLIED WARRANTIES OF
+MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE.
+
+ Copyright (c) 2003-2005 Chelsio Communications. All rights reserved.
+
+===============================================================================