The Linux SYM-2 driver documentation file Written by Gerard Roudier 21 Rue Carnot 95170 DEUIL LA BARRE - FRANCE Updated by Matthew Wilcox 2004-10-09 =============================================================================== 1. Introduction 2. Supported chips and SCSI features 3. Advantages of this driver for newer chips. 3.1 Optimized SCSI SCRIPTS 3.2 New features appeared with the SYM53C896 4. Memory mapped I/O versus normal I/O 5. Tagged command queueing 6. Parity checking 7. Profiling information 8. Control commands 8.1 Set minimum synchronous period 8.2 Set wide size 8.3 Set maximum number of concurrent tagged commands 8.4 Set debug mode 8.5 Set flag (no_disc) 8.6 Set verbose level 8.7 Reset all logical units of a target 8.8 Abort all tasks of all logical units of a target 9. Configuration parameters 10. Boot setup commands 10.1 Syntax 10.2 Available arguments 10.2.1 Default number of tagged commands 10.2.2 Burst max 10.2.3 LED support 10.2.4 Differential mode 10.2.5 IRQ mode 10.2.6 Check SCSI BUS 10.2.7 Suggest a default SCSI id for hosts 10.2.8 Verbosity level 10.2.9 Debug mode 10.2.10 Settle delay 10.2.11 Serial NVRAM 10.2.12 Exclude a host from being attached 10.3 Converting from old options 10.4 SCSI BUS checking boot option 11. SCSI problem troubleshooting 15.1 Problem tracking 15.2 Understanding hardware error reports 12. Serial NVRAM support (by Richard Waltham) 17.1 Features 17.2 Symbios NVRAM layout 17.3 Tekram NVRAM layout =============================================================================== 1. Introduction This driver supports the whole SYM53C8XX family of PCI-SCSI controllers. It also support the subset of LSI53C10XX PCI-SCSI controllers that are based on the SYM53C8XX SCRIPTS language. It replaces the sym53c8xx+ncr53c8xx driver bundle and shares its core code with the FreeBSD SYM-2 driver. The `glue' that allows this driver to work under Linux is contained in 2 files named sym_glue.h and sym_glue.c. Other drivers files are intended not to depend on the Operating System on which the driver is used. The history of this driver can be summarized as follows: 1993: ncr driver written for 386bsd and FreeBSD by: Wolfgang Stanglmeier Stefan Esser 1996: port of the ncr driver to Linux-1.2.13 and rename it ncr53c8xx. Gerard Roudier 1998: new sym53c8xx driver for Linux based on LOAD/STORE instruction and that adds full support for the 896 but drops support for early NCR devices. Gerard Roudier 1999: port of the sym53c8xx driver to FreeBSD and support for the LSI53C1010 33 MHz and 66MHz Ultra-3 controllers. The new driver is named `sym'. Gerard Roudier 2000: Add support for early NCR devices to FreeBSD `sym' driver. Break the driver into several sources and separate the OS glue code from the core code that can be shared among different O/Ses. Write a glue code for Linux. Gerard Roudier 2004: Remove FreeBSD compatibility code. Remove support for versions of Linux before 2.6. Start using Linux facilities. This README file addresses the Linux version of the driver. Under FreeBSD, the driver documentation is the sym.8 man page. Information about new chips is available at LSILOGIC web server: http://www.lsilogic.com/ SCSI standard documentations are available at T10 site: http://www.t10.org/ Useful SCSI tools written by Eric Youngdale are part of most Linux distributions: scsiinfo: command line tool scsi-config: TCL/Tk tool using scsiinfo 2. Supported chips and SCSI features The following features are supported for all chips: Synchronous negotiation Disconnection Tagged command queuing SCSI parity checking PCI Master parity checking Other features depends on chip capabilities. The driver notably uses optimized SCRIPTS for devices that support LOAD/STORE and handles PHASE MISMATCH from SCRIPTS for devices that support the corresponding feature. The following table shows some characteristics of the chip family. On board LOAD/STORE HARDWARE Chip SDMS BIOS Wide SCSI std. Max. sync SCRIPTS PHASE MISMATCH ---- --------- ---- --------- ---------- ---------- -------------- 810 N N FAST10 10 MB/s N N 810A N N FAST10 10 MB/s Y N 815 Y N FAST10 10 MB/s N N 825 Y Y FAST10 20 MB/s N N 825A Y Y FAST10 20 MB/s Y N 860 N N FAST20 20 MB/s Y N 875 Y Y FAST20 40 MB/s Y N 875A Y Y FAST20 40 MB/s Y Y 876 Y Y FAST20 40 MB/s Y N 895 Y Y FAST40 80 MB/s Y N 895A Y Y FAST40 80 MB/s Y Y 896 Y Y FAST40 80 MB/s Y Y 897 Y Y FAST40 80 MB/s Y Y 1510D Y Y FAST40 80 MB/s Y Y 1010 Y Y FAST80 160 MB/s Y Y 1010_66* Y Y FAST80 160 MB/s Y Y * Chip supports 33MHz and 66MHz PCI bus clock. Summary of other supported features: Module: allow to load the driver Memory mapped I/O: increases performance Control commands: write operations to the proc SCSI file system Debugging information: written to syslog (expert only) Scatter / gather Shared interrupt Boot setup commands Serial NVRAM: Symbios and Tekram formats 3. Advantages of this driver for newer chips. 3.1 Optimized SCSI SCRIPTS. All chips except the 810, 815 and 825, support new SCSI SCRIPTS instructions named LOAD and STORE that allow to move up to 1 DWORD from/to an IO register to/from memory much faster that the MOVE MEMORY instruction that is supported by the 53c7xx and 53c8xx family. The LOAD/STORE instructions support absolute and DSA relative addressing modes. The SCSI SCRIPTS had been entirely rewritten using LOAD/STORE instead of MOVE MEMORY instructions. Due to the lack of LOAD/STORE SCRIPTS instructions by earlier chips, this driver also incorporates a different SCRIPTS set based on MEMORY MOVE, in order to provide support for the entire SYM53C8XX chips family. 3.2 New features appeared with the SYM53C896 Newer chips (see above) allows handling of the phase mismatch context from SCRIPTS (avoids the phase mismatch interrupt that stops the SCSI processor until the C code has saved the context of the transfer). The 896 and 1010 chips support 64 bit PCI transactions and addressing, while the 895A supports 32 bit PCI transactions and 64 bit addressing. The SCRIPTS processor of these chips is not true 64 bit, but uses segment registers for bit 32-63. Another interesting feature is that LOAD/STORE instructions that address the on-chip RAM (8k) remain internal to the chip. 4. Memory mapped I/O versus normal I/O Memory mapped I/O has less latency than normal I/O and is the recommended way for doing IO with PCI devices. Memory mapped I/O seems to work fine on most hardware configurations, but some poorly designed chipsets may break this feature. A configuration option is provided for normal I/O to be used but the driver defaults to MMIO. 5. Tagged command queueing Queuing more than 1 command at a time to a device allows it to perform optimizations based on actual head positions and its mechanical characteristics. This feature may also reduce average command latency. In order to really gain advantage of this feature, devices must have a reasonable cache size (No miracle is to be expected for a low-end hard disk with 128 KB or less). Some known old SCSI devices do not properly support tagged command queuing. Generally, firmware revisions that fix this kind of problems are available at respective vendor web/ftp sites. All I can say is that I never have had problem with tagged queuing using this driver and its predecessors. Hard disks that behaved correctly for me using tagged commands are the following: - IBM S12 0662 - Conner 1080S - Quantum Atlas I - Quantum Atlas II - Seagate Cheetah I - Quantum Viking II - IBM DRVS - Quantum Atlas IV - Seagate Cheetah II If your controller has NVRAM, you can configure this feature per target from the user setup tool. The Tekram Setup program allows to tune the maximum number of queued commands up to 32. The Symbios Setup only allows to enable or disable this feature. The maximum number of simultaneous tagged commands queued to a device is currently set to 16 by default. This value is suitable for most SCSI disks. With large SCSI disks (>= 2GB, cache >= 512KB, average seek time <= 10 ms), using a larger value may give better performances. This driver supports up to 255 commands per device, and but using more than 64 is generally not worth-while, unless you are using a very large disk or disk arrays. It is noticeable that most of recent hard disks seem not to accept more than 64 simultaneous commands. So, using more than 64 queued commands is probably just resource wasting. If your controller does not have NVRAM or if it is managed by the SDMS BIOS/SETUP, you can configure tagged queueing feature and device queue depths from the boot command-line. For example: sym53c8xx=tags:4/t2t3q15-t4q7/t1u0q32 will set tagged commands queue depths as follow: - target 2 all luns on controller 0 --> 15 - target 3 all luns on controller 0 --> 15 - target 4 all luns on controller 0 --> 7 - target 1 lun 0 on controller 1 --> 32 - all other target/lun --> 4 In some special conditions, some SCSI disk firmwares may return a QUEUE FULL status for a SCSI command. This behaviour is managed by the driver using the following heuristic: - Each time a QUEUE FULL status is returned, tagged queue depth is reduced to the actual number of disconnected commands. - Every 200 successfully completed SCSI commands, if allowed by the current limit, the maximum number of queueable commands is incremented. Since QUEUE FULL status reception and handling is resource wasting, the driver notifies by default this problem to user by indicating the actual number of commands used and their status, as well as its decision on the device queue depth change. The heuristic used by the driver in handling QUEUE FULL ensures that the impact on performances is not too bad. You can get rid of the messages by setting verbose level to zero, as follow: 1st method: boot your system using 'sym53c8xx=verb:0' option. 2nd method: apply "setverbose 0" control command to the proc fs entry corresponding to your controller after boot-up. 6. Parity checking The driver supports SCSI parity checking and PCI bus master parity checking. These features must be enabled in order to ensure safe data transfers. Some flawed devices or mother boards may have problems with parity. The options to defeat parity checking have been removed from the driver. 7. Profiling information This driver does not provide profiling informations as did its predecessors. This feature was not this useful and added complexity to the code. As the driver code got more complex, I have decided to remove everything that didn't seem actually useful. 8. Control commands Control commands can be sent to the driver with write operations to the proc SCSI file system. The generic command syntax is the following: echo " " >/proc/scsi/sym53c8xx/0 (assumes controller number is 0) Using "all" for "" parameter with the commands below will apply to all targets of the SCSI chain (except the controller). Available commands: 8.1 Set minimum synchronous period factor setsync target: target number period: minimum synchronous period. Maximum speed = 1000/(4*period factor) except for special cases below. Specify a period of 0, to force asynchronous transfer mode. 9 means 12.5 nano-seconds synchronous period 10 means 25 nano-seconds synchronous period 11 means 30 nano-seconds synchronous period 12 means 50 nano-seconds synchronous period 8.2 Set wide size setwide target: target number size: 0=8 bits, 1=16bits 8.3 Set maximum number of concurrent tagged commands settags target: target number tags: number of concurrent tagged commands must not be greater than configured (default: 16) 8.4 Set debug mode setdebug Available debug flags: alloc: print info about memory allocations (ccb, lcb) queue: print info about insertions into the command start queue result: print sense data on CHECK CONDITION status scatter: print info about the scatter process scripts: print info about the script binding process tiny: print minimal debugging information timing: print timing information of the NCR chip nego: print information about SCSI negotiations phase: print information on script interruptions Use "setdebug" with no argument to reset debug flags. 8.5 Set flag (no_disc) setflag target: target number For the moment, only one flag is available: no_disc: not allow target to disconnect. Do not specify any flag in order to reset the flag. For example: - setflag 4 will reset no_disc flag for target 4, so will allow it disconnections. - setflag all will allow disconnection for all devices on the SCSI bus. 8.6 Set verbose level setverbose #level The driver default verbose level is 1. This command allows to change th driver verbose level after boot-up. 8.7 Reset all logical units of a target resetdev target: target number The driver will try to send a BUS DEVICE RESET message to the target. 8.8 Abort all tasks of all logical units of a target cleardev target: target number The driver will try to send a ABORT message to all the logical units of the target. 9. Configuration parameters Under kernel configuration tools (make menuconfig, for example), it is possible to change some default driver configuration parameters. If the firmware of all your devices is perfect enough, all the features supported by the driver can be enabled at start-up. However, if only one has a flaw for some SCSI feature, you can disable the support by the driver of this feature at linux start-up and enable this feature after boot-up only for devices that support it safely. Configuration parameters: Use normal IO (default answer: n) Answer "y" if you suspect your mother board to not allow memory mapped I/O. May slow down performance a little. Default tagged command queue depth (default answer: 16) Entering 0 defaults to tagged commands not being used. This parameter can be specified from the boot command line. Maximum number of queued commands (default answer: 32) This option allows you to specify the maximum number of tagged commands that can be queued to a device. The maximum supported value is 255. Synchronous transfers frequency (default answer: 80) This option allows you to specify the frequency in MHz the driver will use at boot time for synchronous data transfer negotiations. 0 means "asynchronous data transfers". 10. Boot setup commands 10.1 Syntax Setup commands can be passed to the driver either at boot time or as parameters to modprobe, as described in Documentation/kernel-parameters.txt Example of boot setup command under lilo prompt: lilo: linux root=/dev/sda2 sym53c8xx.cmd_per_lun=4 sym53c8xx.sync=10 sym53c8xx.debug=0x200 - enable tagged commands, up to 4 tagged commands queued. - set synchronous negotiation speed to 10 Mega-transfers / second. - set DEBUG_NEGO flag. The following command will install the driver module with the same options as above. modprobe sym53c8xx cmd_per_lun=4 sync=10 debug=0x200 10.2 Available arguments 10.2.1 Default number of tagged commands cmd_per_lun=0 (or cmd_per_lun=1) tagged command queuing disabled cmd_per_lun=#tags (#tags > 1) tagged command queuing enabled #tags will be truncated to the max queued commands configuration parameter. 10.2.2 Burst max burst=0 burst disabled burst=255 get burst length from initial IO register settings. burst=#x burst enabled (1<<#x burst transfers max) #x is an integer value which is log base 2 of the burst transfers max. By default the driver uses the maximum value supported by the chip. 10.2.3 LED support led=1 enable LED support led=0 disable LED support Do not enable LED support if your scsi board does not use SDMS BIOS. (See 'Configuration parameters') 10.2.4 Differential mode diff=0 never set up diff mode diff=1 set up diff mode if BIOS set it diff=2 always set up diff mode diff=3 set diff mode if GPIO3 is not set 10.2.5 IRQ mode irqm=0 always open drain irqm=1 same as initial settings (assumed BIOS settings) irqm=2 always totem pole 10.2.6 Check SCSI BUS buschk=