| The Linux NCR53C8XX/SYM53C8XX drivers README file |
| |
| Written by Gerard Roudier <groudier@free.fr> |
| 21 Rue Carnot |
| 95170 DEUIL LA BARRE - FRANCE |
| |
| 29 May 1999 |
| =============================================================================== |
| |
| 1. Introduction |
| 2. Supported chips and SCSI features |
| 3. Advantages of the enhanced 896 driver |
| 3.1 Optimized SCSI SCRIPTS |
| 3.2 New features of the SYM53C896 (64 bit PCI dual LVD SCSI controller) |
| 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 order type for tagged command |
| 8.5 Set debug mode |
| 8.6 Clear profile counters |
| 8.7 Set flag (no_disc) |
| 8.8 Set verbose level |
| 8.9 Reset all logical units of a target |
| 8.10 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 Master parity checking |
| 10.2.2 Scsi parity checking |
| 10.2.3 Scsi disconnections |
| 10.2.4 Special features |
| 10.2.5 Ultra SCSI support |
| 10.2.6 Default number of tagged commands |
| 10.2.7 Default synchronous period factor |
| 10.2.8 Negotiate synchronous with all devices |
| 10.2.9 Verbosity level |
| 10.2.10 Debug mode |
| 10.2.11 Burst max |
| 10.2.12 LED support |
| 10.2.13 Max wide |
| 10.2.14 Differential mode |
| 10.2.15 IRQ mode |
| 10.2.16 Reverse probe |
| 10.2.17 Fix up PCI configuration space |
| 10.2.18 Serial NVRAM |
| 10.2.19 Check SCSI BUS |
| 10.2.20 Exclude a host from being attached |
| 10.2.21 Suggest a default SCSI id for hosts |
| 10.2.22 Enable use of IMMEDIATE ARBITRATION |
| 10.3 Advised boot setup commands |
| 10.4 PCI configuration fix-up boot option |
| 10.5 Serial NVRAM support boot option |
| 10.6 SCSI BUS checking boot option |
| 10.7 IMMEDIATE ARBITRATION boot option |
| 11. Some constants and flags of the ncr53c8xx.h header file |
| 12. Installation |
| 13. Architecture dependent features |
| 14. Known problems |
| 14.1 Tagged commands with Iomega Jaz device |
| 14.2 Device names change when another controller is added |
| 14.3 Using only 8 bit devices with a WIDE SCSI controller. |
| 14.4 Possible data corruption during a Memory Write and Invalidate |
| 14.5 IRQ sharing problems |
| 15. SCSI problem troubleshooting |
| 15.1 Problem tracking |
| 15.2 Understanding hardware error reports |
| 16. Synchronous transfer negotiation tables |
| 16.1 Synchronous timings for 53C875 and 53C860 Ultra-SCSI controllers |
| 16.2 Synchronous timings for fast SCSI-2 53C8XX controllers |
| 17. Serial NVRAM support (by Richard Waltham) |
| 17.1 Features |
| 17.2 Symbios NVRAM layout |
| 17.3 Tekram NVRAM layout |
| 18. Support for Big Endian |
| 18.1 Big Endian CPU |
| 18.2 NCR chip in Big Endian mode of operations |
| |
| =============================================================================== |
| |
| 1. Introduction |
| |
| The initial Linux ncr53c8xx driver has been a port of the ncr driver from |
| FreeBSD that has been achieved in November 1995 by: |
| Gerard Roudier <groudier@free.fr> |
| |
| The original driver has been written for 386bsd and FreeBSD by: |
| Wolfgang Stanglmeier <wolf@cologne.de> |
| Stefan Esser <se@mi.Uni-Koeln.de> |
| |
| It is now available as a bundle of 2 drivers: |
| |
| - ncr53c8xx generic driver that supports all the SYM53C8XX family including |
| the earliest 810 rev. 1, the latest 896 (2 channel LVD SCSI controller) and |
| the new 895A (1 channel LVD SCSI controller). |
| - sym53c8xx enhanced driver (a.k.a. 896 drivers) that drops support of oldest |
| chips in order to gain advantage of new features, as LOAD/STORE instructions |
| available since the 810A and hardware phase mismatch available with the |
| 896 and the 895A. |
| |
| You can find technical information about the NCR 8xx family in the |
| PCI-HOWTO written by Michael Will and in the SCSI-HOWTO written by |
| Drew Eckhardt. |
| |
| Information about new chips is available at LSILOGIC web server: |
| |
| http://www.lsilogic.com/ |
| |
| SCSI standard documentations are available at SYMBIOS ftp server: |
| |
| ftp://ftp.symbios.com/ |
| |
| Useful SCSI tools written by Eric Youngdale are available at tsx-11: |
| |
| ftp://tsx-11.mit.edu/pub/linux/ALPHA/scsi/scsiinfo-X.Y.tar.gz |
| ftp://tsx-11.mit.edu/pub/linux/ALPHA/scsi/scsidev-X.Y.tar.gz |
| |
| These tools are not ALPHA but quite clean and work quite well. |
| It is essential you have the 'scsiinfo' package. |
| |
| This short documentation describes the features of the generic and enhanced |
| drivers, configuration parameters and control commands available through |
| the proc SCSI file system read / write operations. |
| |
| This driver has been tested OK with linux/i386, Linux/Alpha and Linux/PPC. |
| |
| Latest driver version and patches are available at: |
| |
| ftp://ftp.tux.org/pub/people/gerard-roudier |
| or |
| ftp://ftp.symbios.com/mirror/ftp.tux.org/pub/tux/roudier/drivers |
| |
| I am not a native speaker of English and there are probably lots of |
| mistakes in this README file. Any help will be welcome. |
| |
| |
| 2. Supported chips and SCSI features |
| |
| The following features are supported for all chips: |
| |
| Synchronous negotiation |
| Disconnection |
| Tagged command queuing |
| SCSI parity checking |
| Master parity checking |
| |
| "Wide negotiation" is supported for chips that allow it. The |
| following table shows some characteristics of NCR 8xx family chips |
| and what drivers support them. |
| |
| Supported by Supported by |
| On board the generic the enhanced |
| Chip SDMS BIOS Wide SCSI std. Max. sync driver driver |
| ---- --------- ---- --------- ---------- ------------ ------------- |
| 810 N N FAST10 10 MB/s Y N |
| 810A N N FAST10 10 MB/s Y Y |
| 815 Y N FAST10 10 MB/s Y N |
| 825 Y Y FAST10 20 MB/s Y N |
| 825A Y Y FAST10 20 MB/s Y Y |
| 860 N N FAST20 20 MB/s Y Y |
| 875 Y Y FAST20 40 MB/s Y Y |
| 876 Y Y FAST20 40 MB/s Y Y |
| 895 Y Y FAST40 80 MB/s Y Y |
| 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 N Y |
| 1010_66* Y Y FAST80 160 MB/s N Y |
| |
| * Chip supports 33MHz and 66MHz PCI buses. |
| |
| |
| Summary of other supported features: |
| |
| Module: allow to load the driver |
| Memory mapped I/O: increases performance |
| Profiling information: read operations from the proc SCSI file system |
| 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 the enhanced 896 driver |
| |
| 3.1 Optimized SCSI SCRIPTS. |
| |
| The 810A, 825A, 875, 895, 896 and 895A 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. |
| |
| 3.2 New features of the SYM53C896 (64 bit PCI dual LVD SCSI controller) |
| |
| The 896 and the 895A 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). |
| Implementing this without using LOAD/STORE instructions would be painfull |
| and I didn't even want to try it. |
| |
| The 896 chip supports 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. |
| |
| Due to the use of LOAD/STORE SCRIPTS instructions, this driver does not |
| support the following chips: |
| - SYM53C810 revision < 0x10 (16) |
| - SYM53C815 all revisions |
| - SYM53C825 revision < 0x10 (16) |
| |
| 4. Memory mapped I/O versus normal I/O |
| |
| Memory mapped I/O has less latency than normal I/O. Since |
| linux-1.3.x, memory mapped I/O is used rather than normal I/O. Memory |
| mapped I/O seems to work fine on most hardware configurations, but |
| some poorly designed motherboards may break this feature. |
| |
| The configuration option CONFIG_SCSI_NCR53C8XX_IOMAPPED forces the |
| driver to use normal I/O in all cases. |
| |
| |
| 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 kown 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 the hard disks I use on my machines behave well with |
| this driver with tagged command queuing enabled: |
| |
| - IBM S12 0662 |
| - Conner 1080S |
| - Quantum Atlas I |
| - Quantum Atlas 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 8 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. |
| |
| The sym53c8xx driver supports up to 255 commands per device, and the |
| generic ncr53c8xx driver supports up to 64, but using more than 32 is |
| generally not worth-while, unless you are using a very large disk or disk |
| array. 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: |
| |
| ncr53c8xx=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 1000 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 'ncr53c8xx=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. However, some flawed devices or mother boards will have |
| problems with parity. You can disable either PCI parity or SCSI parity |
| checking by entering appropriate options from the boot command line. |
| (See 10: Boot setup commands). |
| |
| 7. Profiling information |
| |
| Profiling information is available through the proc SCSI file system. |
| Since gathering profiling information may impact performances, this |
| feature is disabled by default and requires a compilation configuration |
| option to be set to Y. |
| |
| The device associated with a host has the following pathname: |
| |
| /proc/scsi/ncr53c8xx/N (N=0,1,2 ....) |
| |
| Generally, only 1 board is used on hardware configuration, and that device is: |
| /proc/scsi/ncr53c8xx/0 |
| |
| However, if the driver has been made as module, the number of the |
| hosts is incremented each time the driver is loaded. |
| |
| In order to display profiling information, just enter: |
| |
| cat /proc/scsi/ncr53c8xx/0 |
| |
| and you will get something like the following text: |
| |
| ------------------------------------------------------- |
| General information: |
| Chip NCR53C810, device id 0x1, revision id 0x2 |
| IO port address 0x6000, IRQ number 10 |
| Using memory mapped IO at virtual address 0x282c000 |
| Synchronous transfer period 25, max commands per lun 4 |
| Profiling information: |
| num_trans = 18014 |
| num_kbytes = 671314 |
| num_disc = 25763 |
| num_break = 1673 |
| num_int = 1685 |
| num_fly = 18038 |
| ms_setup = 4940 |
| ms_data = 369940 |
| ms_disc = 183090 |
| ms_post = 1320 |
| ------------------------------------------------------- |
| |
| General information is easy to understand. The device ID and the |
| revision ID identify the SCSI chip as follows: |
| |
| Chip Device id Revision Id |
| ---- --------- ----------- |
| 810 0x1 < 0x10 |
| 810A 0x1 >= 0x10 |
| 815 0x4 |
| 825 0x3 < 0x10 |
| 860 0x6 |
| 825A 0x3 >= 0x10 |
| 875 0xf |
| 895 0xc |
| |
| The profiling information is updated upon completion of SCSI commands. |
| A data structure is allocated and zeroed when the host adapter is |
| attached. So, if the driver is a module, the profile counters are |
| cleared each time the driver is loaded. The "clearprof" command |
| allows you to clear these counters at any time. |
| |
| The following counters are available: |
| |
| ("num" prefix means "number of", |
| "ms" means milli-seconds) |
| |
| num_trans |
| Number of completed commands |
| Example above: 18014 completed commands |
| |
| num_kbytes |
| Number of kbytes transferred |
| Example above: 671 MB transferred |
| |
| num_disc |
| Number of SCSI disconnections |
| Example above: 25763 SCSI disconnections |
| |
| num_break |
| number of script interruptions (phase mismatch) |
| Example above: 1673 script interruptions |
| |
| num_int |
| Number of interrupts other than "on the fly" |
| Example above: 1685 interruptions not "on the fly" |
| |
| num_fly |
| Number of interrupts "on the fly" |
| Example above: 18038 interruptions "on the fly" |
| |
| ms_setup |
| Elapsed time for SCSI commands setups |
| Example above: 4.94 seconds |
| |
| ms_data |
| Elapsed time for data transfers |
| Example above: 369.94 seconds spent for data transfer |
| |
| ms_disc |
| Elapsed time for SCSI disconnections |
| Example above: 183.09 seconds spent disconnected |
| |
| ms_post |
| Elapsed time for command post processing |
| (time from SCSI status get to command completion call) |
| Example above: 1.32 seconds spent for post processing |
| |
| Due to the 1/100 second tick of the system clock, "ms_post" time may |
| be wrong. |
| |
| In the example above, we got 18038 interrupts "on the fly" and only |
| 1673 script breaks generally due to disconnections inside a segment |
| of the scatter list. |
| |
| |
| 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 "<verb> <parameters>" >/proc/scsi/ncr53c8xx/0 |
| (assumes controller number is 0) |
| |
| Using "all" for "<target>" 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> <period factor> |
| |
| target: target number |
| period: minimum synchronous period. |
| Maximum speed = 1000/(4*period factor) except for special |
| cases below. |
| |
| Specify a period of 255, to force asynchronous transfer mode. |
| |
| 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> <size> |
| |
| target: target number |
| size: 0=8 bits, 1=16bits |
| |
| 8.3 Set maximum number of concurrent tagged commands |
| |
| settags <target> <tags> |
| |
| target: target number |
| tags: number of concurrent tagged commands |
| must not be greater than SCSI_NCR_MAX_TAGS (default: 8) |
| |
| 8.4 Set order type for tagged command |
| |
| setorder <order> |
| |
| order: 3 possible values: |
| simple: use SIMPLE TAG for all operations (read and write) |
| ordered: use ORDERED TAG for all operations |
| default: use default tag type, |
| SIMPLE TAG for read operations |
| ORDERED TAG for write operations |
| |
| |
| 8.5 Set debug mode |
| |
| setdebug <list of debug flags> |
| |
| 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. |
| |
| |
| 8.6 Clear profile counters |
| |
| clearprof |
| |
| The profile counters are automatically cleared when the amount of |
| data transferred reaches 1000 GB in order to avoid overflow. |
| The "clearprof" command allows you to clear these counters at any time. |
| |
| |
| 8.7 Set flag (no_disc) |
| |
| setflag <target> <flag> |
| |
| 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. |
| |
| |
| 8.8 Set verbose level |
| |
| setverbose #level |
| |
| The driver default verbose level is 1. This command allows to change |
| th driver verbose level after boot-up. |
| |
| 8.9 Reset all logical units of a target |
| |
| resetdev <target> |
| |
| target: target number |
| The driver will try to send a BUS DEVICE RESET message to the target. |
| (Only supported by the SYM53C8XX driver and provided for test purpose) |
| |
| 8.10 Abort all tasks of all logical units of a target |
| |
| cleardev <target> |
| |
| target: target number |
| The driver will try to send a ABORT message to all the logical units |
| of the target. |
| (Only supported by the SYM53C8XX driver and provided for test purpose) |
| |
| |
| 9. 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. |
| |
| CONFIG_SCSI_NCR53C8XX_IOMAPPED (default answer: n) |
| Answer "y" if you suspect your mother board to not allow memory mapped I/O. |
| May slow down performance a little. This option is required by |
| Linux/PPC and is used no matter what you select here. Linux/PPC |
| suffers no performance loss with this option since all IO is memory |
| mapped anyway. |
| |
| CONFIG_SCSI_NCR53C8XX_DEFAULT_TAGS (default answer: 8) |
| Default tagged command queue depth. |
| |
| CONFIG_SCSI_NCR53C8XX_MAX_TAGS (default answer: 8) |
| This option allows you to specify the maximum number of tagged commands |
| that can be queued to a device. The maximum supported value is 32. |
| |
| CONFIG_SCSI_NCR53C8XX_SYNC (default answer: 5) |
| This option allows you to specify the frequency in MHz the driver |
| will use at boot time for synchronous data transfer negotiations. |
| This frequency can be changed later with the "setsync" control command. |
| 0 means "asynchronous data transfers". |
| |
| CONFIG_SCSI_NCR53C8XX_FORCE_SYNC_NEGO (default answer: n) |
| Force synchronous negotiation for all SCSI-2 devices. |
| Some SCSI-2 devices do not report this feature in byte 7 of inquiry |
| response but do support it properly (TAMARACK scanners for example). |
| |
| CONFIG_SCSI_NCR53C8XX_NO_DISCONNECT (default and only reasonable answer: n) |
| If you suspect a device of yours does not properly support disconnections, |
| you can answer "y". Then, all SCSI devices will never disconnect the bus |
| even while performing long SCSI operations. |
| |
| CONFIG_SCSI_NCR53C8XX_SYMBIOS_COMPAT |
| Genuine SYMBIOS boards use GPIO0 in output for controller LED and GPIO3 |
| bit as a flag indicating singled-ended/differential interface. |
| If all the boards of your system are genuine SYMBIOS boards or use |
| BIOS and drivers from SYMBIOS, you would want to enable this option. |
| This option must NOT be enabled if your system has at least one 53C8XX |
| based scsi board with a vendor-specific BIOS. |
| For example, Tekram DC-390/U, DC-390/W and DC-390/F scsi controllers |
| use a vendor-specific BIOS and are known to not use SYMBIOS compatible |
| GPIO wiring. So, this option must not be enabled if your system has |
| such a board installed. |
| |
| CONFIG_SCSI_NCR53C8XX_NVRAM_DETECT |
| Enable support for reading the serial NVRAM data on Symbios and |
| some Symbios compatible cards, and Tekram DC390W/U/F cards. Useful for |
| systems with more than one Symbios compatible controller where at least |
| one has a serial NVRAM, or for a system with a mixture of Symbios and |
| Tekram cards. Enables setting the boot order of host adaptors |
| to something other than the default order or "reverse probe" order. |
| Also enables Symbios and Tekram cards to be distinguished so |
| CONFIG_SCSI_NCR53C8XX_SYMBIOS_COMPAT may be set in a system with a |
| mixture of Symbios and Tekram cards so the Symbios cards can make use of |
| the full range of Symbios features, differential, led pin, without |
| causing problems for the Tekram card(s). |
| |
| 10. Boot setup commands |
| |
| 10.1 Syntax |
| |
| Setup commands can be passed to the driver either at boot time or as a |
| string variable using 'insmod'. |
| |
| A boot setup command for the ncr53c8xx (sym53c8xx) driver begins with the |
| driver name "ncr53c8xx="(sym53c8xx). The kernel syntax parser then expects |
| an optional list of integers separated with comma followed by an optional |
| list of comma-separated strings. Example of boot setup command under lilo |
| prompt: |
| |
| lilo: linux root=/dev/hda2 ncr53c8xx=tags:4,sync:10,debug:0x200 |
| |
| - enable tagged commands, up to 4 tagged commands queued. |
| - set synchronous negotiation speed to 10 Mega-transfers / second. |
| - set DEBUG_NEGO flag. |
| |
| Since comma seems not to be allowed when defining a string variable using |
| 'insmod', the driver also accepts <space> as option separator. |
| The following command will install driver module with the same options as |
| above. |
| |
| insmod ncr53c8xx.o ncr53c8xx="tags:4 sync:10 debug:0x200" |
| |
| For the moment, the integer list of arguments is discarded by the driver. |
| It will be used in the future in order to allow a per controller setup. |
| |
| Each string argument must be specified as "keyword:value". Only lower-case |
| characters and digits are allowed. |
| |
| In a system that contains multiple 53C8xx adapters insmod will install the |
| specified driver on each adapter. To exclude a chip use the 'excl' keyword. |
| |
| The sequence of commands, |
| |
| insmod sym53c8xx sym53c8xx=excl:0x1400 |
| insmod ncr53c8xx |
| |
| installs the sym53c8xx driver on all adapters except the one at IO port |
| address 0x1400 and then installs the ncr53c8xx driver to the adapter at IO |
| port address 0x1400. |
| |
| |
| 10.2 Available arguments |
| |
| 10.2.1 Master parity checking |
| mpar:y enabled |
| mpar:n disabled |
| |
| 10.2.2 Scsi parity checking |
| spar:y enabled |
| spar:n disabled |
| |
| 10.2.3 Scsi disconnections |
| disc:y enabled |
| disc:n disabled |
| |
| 10.2.4 Special features |
| Only apply to 810A, 825A, 860, 875 and 895 controllers. |
| Have no effect with other ones. |
| specf:y (or 1) enabled |
| specf:n (or 0) disabled |
| specf:3 enabled except Memory Write And Invalidate |
| The default driver setup is 'specf:3'. As a consequence, option 'specf:y' |
| must be specified in the boot setup command to enable Memory Write And |
| Invalidate. |
| |
| 10.2.5 Ultra SCSI support |
| Only apply to 860, 875, 895, 895a, 896, 1010 and 1010_66 controllers. |
| Have no effect with other ones. |
| ultra:n All ultra speeds enabled |
| ultra:2 Ultra2 enabled |
| ultra:1 Ultra enabled |
| ultra:0 Ultra speeds disabled |
| |
| 10.2.6 Default number of tagged commands |
| tags:0 (or tags:1 ) tagged command queuing disabled |
| tags:#tags (#tags > 1) tagged command queuing enabled |
| #tags will be truncated to the max queued commands configuration parameter. |
| This option also allows to specify a command queue depth for each device |
| that support tagged command queueing. |
| Example: |
| ncr53c8xx=tags:10/t2t3q16-t5q24/t1u2q32 |
| will set devices queue depth as follow: |
| - controller #0 target #2 and target #3 -> 16 commands, |
| - controller #0 target #5 -> 24 commands, |
| - controller #1 target #1 logical unit #2 -> 32 commands, |
| - all other logical units (all targets, all controllers) -> 10 commands. |
| |
| 10.2.7 Default synchronous period factor |
| sync:255 disabled (asynchronous transfer mode) |
| sync:#factor |
| #factor = 10 Ultra-2 SCSI 40 Mega-transfers / second |
| #factor = 11 Ultra-2 SCSI 33 Mega-transfers / second |
| #factor < 25 Ultra SCSI 20 Mega-transfers / second |
| #factor < 50 Fast SCSI-2 |
| |
| In all cases, the driver will use the minimum transfer period supported by |
| controllers according to NCR53C8XX chip type. |
| |
| 10.2.8 Negotiate synchronous with all devices |
| (force sync nego) |
| fsn:y enabled |
| fsn:n disabled |
| |
| 10.2.9 Verbosity level |
| verb:0 minimal |
| verb:1 normal |
| verb:2 too much |
| |
| 10.2.10 Debug mode |
| debug:0 clear debug flags |
| debug:#x set debug flags |
| #x is an integer value combining the following power-of-2 values: |
| DEBUG_ALLOC 0x1 |
| DEBUG_PHASE 0x2 |
| DEBUG_POLL 0x4 |
| DEBUG_QUEUE 0x8 |
| DEBUG_RESULT 0x10 |
| DEBUG_SCATTER 0x20 |
| DEBUG_SCRIPT 0x40 |
| DEBUG_TINY 0x80 |
| DEBUG_TIMING 0x100 |
| DEBUG_NEGO 0x200 |
| DEBUG_TAGS 0x400 |
| DEBUG_FREEZE 0x800 |
| DEBUG_RESTART 0x1000 |
| |
| You can play safely with DEBUG_NEGO. However, some of these flags may |
| generate bunches of syslog messages. |
| |
| 10.2.11 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. |
| The NCR53C875 and NCR53C825A support up to 128 burst transfers (#x = 7). |
| Other chips only support up to 16 (#x = 4). |
| This is a maximum value. The driver set the burst length according to chip |
| and revision ids. By default the driver uses the maximum value supported |
| by the chip. |
| |
| 10.2.12 LED support |
| led:1 enable LED support |
| led:0 disable LED support |
| Donnot enable LED support if your scsi board does not use SDMS BIOS. |
| (See 'Configuration parameters') |
| |
| 10.2.13 Max wide |
| wide:1 wide scsi enabled |
| wide:0 wide scsi disabled |
| Some scsi boards use a 875 (ultra wide) and only supply narrow connectors. |
| If you have connected a wide device with a 50 pins to 68 pins cable |
| converter, any accepted wide negotiation will break further data transfers. |
| In such a case, using "wide:0" in the bootup command will be helpful. |
| |
| 10.2.14 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 |
| |
| 10.2.15 IRQ mode |
| irqm:0 always open drain |
| irqm:1 same as initial settings (assumed BIOS settings) |
| irqm:2 always totem pole |
| irqm:0x10 driver will not use SA_SHIRQ flag when requesting irq |
| irqm:0x20 driver will not use SA_INTERRUPT flag when requesting irq |
| |
| (Bits 0x10 and 0x20 can be combined with hardware irq mode option) |
| |
| 10.2.16 Reverse probe |
| revprob:n probe chip ids from the PCI configuration in this order: |
| 810, 815, 820, 860, 875, 885, 895, 896 |
| revprob:y probe chip ids in the reverse order. |
| |
| 10.2.17 Fix up PCI configuration space |
| pcifix:<option bits> |
| |
| Available option bits: |
| 0x0: No attempt to fix PCI configuration space registers values. |
| 0x1: Set PCI cache-line size register if not set. |
| 0x2: Set write and invalidate bit in PCI command register. |
| 0x4: Increase if necessary PCI latency timer according to burst max. |
| |
| Use 'pcifix:7' in order to allow the driver to fix up all PCI features. |
| |
| 10.2.18 Serial NVRAM |
| nvram:n do not look for serial NVRAM |
| nvram:y test controllers for onboard serial NVRAM |
| (alternate binary form) |
| mvram=<bits options> |
| 0x01 look for NVRAM (equivalent to nvram=y) |
| 0x02 ignore NVRAM "Synchronous negotiation" parameters for all devices |
| 0x04 ignore NVRAM "Wide negotiation" parameter for all devices |
| 0x08 ignore NVRAM "Scan at boot time" parameter for all devices |
| 0x80 also attach controllers set to OFF in the NVRAM (sym53c8xx only) |
| |
| 10.2.19 Check SCSI BUS |
| buschk:<option bits> |
| |
| Available option bits: |
| 0x0: No check. |
| 0x1: Check and do not attach the controller on error. |
| 0x2: Check and just warn on error. |
| 0x4: Disable SCSI bus integrity checking. |
| |
| 10.2.20 Exclude a host from being attached |
| excl=<io_address> |
| |
| Prevent host at a given io address from being attached. |
| For example 'ncr53c8xx=excl:0xb400,excl:0xc000' indicate to the |
| ncr53c8xx driver not to attach hosts at address 0xb400 and 0xc000. |
| |
| 10.2.21 Suggest a default SCSI id for hosts |
| hostid:255 no id suggested. |
| hostid:#x (0 < x < 7) x suggested for hosts SCSI id. |
| |
| If a host SCSI id is available from the NVRAM, the driver will ignore |
| any value suggested as boot option. Otherwise, if a suggested value |
| different from 255 has been supplied, it will use it. Otherwise, it will |
| try to deduce the value previously set in the hardware and use value |
| 7 if the hardware value is zero. |
| |
| 10.2.22 Enable use of IMMEDIATE ARBITRATION |
| (only supported by the sym53c8xx driver. See 10.7 for more details) |
| iarb:0 do not use this feature. |
| iarb:#x use this feature according to bit fields as follow: |
| |
| bit 0 (1) : enable IARB each time the initiator has been reselected |
| when it arbitrated for the SCSI BUS. |
| (#x >> 4) : maximum number of successive settings of IARB if the initiator |
| win arbitration and it has other commands to send to a device. |
| |
| Boot fail safe |
| safe:y load the following assumed fail safe initial setup |
| |
| master parity disabled mpar:n |
| scsi parity enabled spar:y |
| disconnections not allowed disc:n |
| special features disabled specf:n |
| ultra scsi disabled ultra:n |
| force sync negotiation disabled fsn:n |
| reverse probe disabled revprob:n |
| PCI fix up disabled pcifix:0 |
| serial NVRAM enabled nvram:y |
| verbosity level 2 verb:2 |
| tagged command queuing disabled tags:0 |
| synchronous negotiation disabled sync:255 |
| debug flags none debug:0 |
| burst length from BIOS settings burst:255 |
| LED support disabled led:0 |
| wide support disabled wide:0 |
| settle time 10 seconds settle:10 |
| differential support from BIOS settings diff:1 |
| irq mode from BIOS settings irqm:1 |
| SCSI BUS check do not attach on error buschk:1 |
| immediate arbitration disabled iarb:0 |
| |
| 10.3 Advised boot setup commands |
| |
| If the driver has been configured with default options, the equivalent |
| boot setup is: |
| |
| ncr53c8xx=mpar:y,spar:y,disc:y,specf:3,fsn:n,ultra:2,fsn:n,revprob:n,verb:1\ |
| tags:0,sync:50,debug:0,burst:7,led:0,wide:1,settle:2,diff:0,irqm:0 |
| |
| For an installation diskette or a safe but not fast system, |
| boot setup can be: |
| |
| ncr53c8xx=safe:y,mpar:y,disc:y |
| ncr53c8xx=safe:y,disc:y |
| ncr53c8xx=safe:y,mpar:y |
| ncr53c8xx=safe:y |
| |
| My personal system works flawlessly with the following equivalent setup: |
| |
| ncr53c8xx=mpar:y,spar:y,disc:y,specf:1,fsn:n,ultra:2,fsn:n,revprob:n,verb:1\ |
| tags:32,sync:12,debug:0,burst:7,led:1,wide:1,settle:2,diff:0,irqm:0 |
| |
| The driver prints its actual setup when verbosity level is 2. You can try |
| "ncr53c8xx=verb:2" to get the "static" setup of the driver, or add "verb:2" |
| to your boot setup command in order to check the actual setup the driver is |
| using. |
| |
| 10.4 PCI configuration fix-up boot option |
| |
| pcifix:<option bits> |
| |
| Available option bits: |
| 0x1: Set PCI cache-line size register if not set. |
| 0x2: Set write and invalidate bit in PCI command register. |
| |
| Use 'pcifix:3' in order to allow the driver to fix both PCI features. |
| |
| These options only apply to new SYMBIOS chips 810A, 825A, 860, 875 |
| and 895 and are only supported for Pentium and 486 class processors. |
| Recent SYMBIOS 53C8XX scsi processors are able to use PCI read multiple |
| and PCI write and invalidate commands. These features require the |
| cache line size register to be properly set in the PCI configuration |
| space of the chips. On the other hand, chips will use PCI write and |
| invalidate commands only if the corresponding bit is set to 1 in the |
| PCI command register. |
| |
| Not all PCI bioses set the PCI cache line register and the PCI write and |
| invalidate bit in the PCI configuration space of 53C8XX chips. |
| Optimized PCI accesses may be broken for some PCI/memory controllers or |
| make problems with some PCI boards. |
| |
| This fix-up worked flawlessly on my previous system. |
| (MB Triton HX / 53C875 / 53C810A) |
| I use these options at my own risks as you will do if you decide to |
| use them too. |
| |
| |
| 10.5 Serial NVRAM support boot option |
| |
| nvram:n do not look for serial NVRAM |
| nvram:y test controllers for onboard serial NVRAM |
| |
| This option can also been entered as an hexadecimal value that allows |
| to control what information the driver will get from the NVRAM and what |
| information it will ignore. |
| For details see '17. Serial NVRAM support'. |
| |
| When this option is enabled, the driver tries to detect all boards using |
| a Serial NVRAM. This memory is used to hold user set up parameters. |
| |
| The parameters the driver is able to get from the NVRAM depend on the |
| data format used, as follow: |
| |
| Tekram format Symbios format |
| General and host parameters |
| Boot order N Y |
| Host SCSI ID Y Y |
| SCSI parity checking Y Y |
| Verbose boot messages N Y |
| SCSI devices parameters |
| Synchronous transfer speed Y Y |
| Wide 16 / Narrow Y Y |
| Tagged Command Queuing enabled Y Y |
| Disconnections enabled Y Y |
| Scan at boot time N Y |
| |
| In order to speed up the system boot, for each device configured without |
| the "scan at boot time" option, the driver forces an error on the |
| first TEST UNIT READY command received for this device. |
| |
| Some SDMS BIOS revisions seem to be unable to boot cleanly with very fast |
| hard disks. In such a situation you cannot configure the NVRAM with |
| optimized parameters value. |
| |
| The 'nvram' boot option can be entered in hexadecimal form in order |
| to ignore some options configured in the NVRAM, as follow: |
| |
| mvram=<bits options> |
| 0x01 look for NVRAM (equivalent to nvram=y) |
| 0x02 ignore NVRAM "Synchronous negotiation" parameters for all devices |
| 0x04 ignore NVRAM "Wide negotiation" parameter for all devices |
| 0x08 ignore NVRAM "Scan at boot time" parameter for all devices |
| 0x80 also attach controllers set to OFF in the NVRAM (sym53c8xx only) |
| |
| Option 0x80 is only supported by the sym53c8xx driver and is disabled by |
| default. Result is that, by default (option not set), the sym53c8xx driver |
| will not attach controllers set to OFF in the NVRAM. |
| |
| The ncr53c8xx always tries to attach all the controllers. Option 0x80 has |
| not been added to the ncr53c8xx driver, since it has been reported to |
| confuse users who use this driver since a long time. If you desire a |
| controller not to be attached by the ncr53c8xx driver at Linux boot, you |
| must use the 'excl' driver boot option. |
| |
| 10.6 SCSI BUS checking boot option. |
| |
| When this option is set to a non-zero value, the driver checks SCSI lines |
| logic state, 100 micro-seconds after having asserted the SCSI RESET line. |
| The driver just reads SCSI lines and checks all lines read FALSE except RESET. |
| Since SCSI devices shall release the BUS at most 800 nano-seconds after SCSI |
| RESET has been asserted, any signal to TRUE may indicate a SCSI BUS problem. |
| Unfortunately, the following common SCSI BUS problems are not detected: |
| - Only 1 terminator installed. |
| - Misplaced terminators. |
| - Bad quality terminators. |
| On the other hand, either bad cabling, broken devices, not conformant |
| devices, ... may cause a SCSI signal to be wrong when te driver reads it. |
| |
| 10.7 IMMEDIATE ARBITRATION boot option |
| |
| This option is only supported by the SYM53C8XX driver (not by the NCR53C8XX). |
| |
| SYMBIOS 53C8XX chips are able to arbitrate for the SCSI BUS as soon as they |
| have detected an expected disconnection (BUS FREE PHASE). For this process |
| to be started, bit 1 of SCNTL1 IO register must be set when the chip is |
| connected to the SCSI BUS. |
| |
| When this feature has been enabled for the current connection, the chip has |
| every chance to win arbitration if only devices with lower priority are |
| competing for the SCSI BUS. By the way, when the chip is using SCSI id 7, |
| then it will for sure win the next SCSI BUS arbitration. |
| |
| Since, there is no way to know what devices are trying to arbitrate for the |
| BUS, using this feature can be extremely unfair. So, you are not advised |
| to enable it, or at most enable this feature for the case the chip lost |
| the previous arbitration (boot option 'iarb:1'). |
| |
| This feature has the following advantages: |
| |
| a) Allow the initiator with ID 7 to win arbitration when it wants so. |
| b) Overlap at least 4 micro-seconds of arbitration time with the execution |
| of SCRIPTS that deal with the end of the current connection and that |
| starts the next job. |
| |
| Hmmm... But (a) may just prevent other devices from reselecting the initiator, |
| and delay data transfers or status/completions, and (b) may just waste |
| SCSI BUS bandwidth if the SCRIPTS execution lasts more than 4 micro-seconds. |
| |
| The use of IARB needs the SCSI_NCR_IARB_SUPPORT option to have been defined |
| at compile time and the 'iarb' boot option to have been set to a non zero |
| value at boot time. It is not that useful for real work, but can be used |
| to stress SCSI devices or for some applications that can gain advantage of |
| it. By the way, if you experience badnesses like 'unexpected disconnections', |
| 'bad reselections', etc... when using IARB on heavy IO load, you should not |
| be surprised, because force-feeding anything and blocking its arse at the |
| same time cannot work for a long time. :-)) |
| |
| |
| 11. Some constants and flags of the ncr53c8xx.h header file |
| |
| Some of these are defined from the configuration parameters. To |
| change other "defines", you must edit the header file. Do that only |
| if you know what you are doing. |
| |
| SCSI_NCR_SETUP_SPECIAL_FEATURES (default: defined) |
| If defined, the driver will enable some special features according |
| to chip and revision id. |
| For 810A, 860, 825A, 875 and 895 scsi chips, this option enables |
| support of features that reduce load of PCI bus and memory accesses |
| during scsi transfer processing: burst op-code fetch, read multiple, |
| read line, prefetch, cache line, write and invalidate, |
| burst 128 (875 only), large dma fifo (875 only), offset 16 (875 only). |
| Can be changed by the following boot setup command: |
| ncr53c8xx=specf:n |
| |
| SCSI_NCR_IOMAPPED (default: not defined) |
| If defined, normal I/O is forced. |
| |
| SCSI_NCR_SHARE_IRQ (default: defined) |
| If defined, request shared IRQ. |
| |
| SCSI_NCR_MAX_TAGS (default: 8) |
| Maximum number of simultaneous tagged commands to a device. |
| Can be changed by "settags <target> <maxtags>" |
| |
| SCSI_NCR_SETUP_DEFAULT_SYNC (default: 50) |
| Transfer period factor the driver will use at boot time for synchronous |
| negotiation. 0 means asynchronous. |
| Can be changed by "setsync <target> <period factor>" |
| |
| SCSI_NCR_SETUP_DEFAULT_TAGS (default: 8) |
| Default number of simultaneous tagged commands to a device. |
| < 1 means tagged command queuing disabled at start-up. |
| |
| SCSI_NCR_ALWAYS_SIMPLE_TAG (default: defined) |
| Use SIMPLE TAG for read and write commands. |
| Can be changed by "setorder <ordered|simple|default>" |
| |
| SCSI_NCR_SETUP_DISCONNECTION (default: defined) |
| If defined, targets are allowed to disconnect. |
| |
| SCSI_NCR_SETUP_FORCE_SYNC_NEGO (default: not defined) |
| If defined, synchronous negotiation is tried for all SCSI-2 devices. |
| Can be changed by "setsync <target> <period>" |
| |
| SCSI_NCR_SETUP_MASTER_PARITY (default: defined) |
| If defined, master parity checking is enabled. |
| |
| SCSI_NCR_SETUP_MASTER_PARITY (default: defined) |
| If defined, SCSI parity checking is enabled. |
| |
| SCSI_NCR_PROFILE_SUPPORT (default: not defined) |
| If defined, profiling information is gathered. |
| |
| SCSI_NCR_MAX_SCATTER (default: 128) |
| Scatter list size of the driver ccb. |
| |
| SCSI_NCR_MAX_TARGET (default: 16) |
| Max number of targets per host. |
| |
| SCSI_NCR_MAX_HOST (default: 2) |
| Max number of host controllers. |
| |
| SCSI_NCR_SETTLE_TIME (default: 2) |
| Number of seconds the driver will wait after reset. |
| |
| SCSI_NCR_TIMEOUT_ALERT (default: 3) |
| If a pending command will time out after this amount of seconds, |
| an ordered tag is used for the next command. |
| Avoids timeouts for unordered tagged commands. |
| |
| SCSI_NCR_CAN_QUEUE (default: 7*SCSI_NCR_MAX_TAGS) |
| Max number of commands that can be queued to a host. |
| |
| SCSI_NCR_CMD_PER_LUN (default: SCSI_NCR_MAX_TAGS) |
| Max number of commands queued to a host for a device. |
| |
| SCSI_NCR_SG_TABLESIZE (default: SCSI_NCR_MAX_SCATTER-1) |
| Max size of the Linux scatter/gather list. |
| |
| SCSI_NCR_MAX_LUN (default: 8) |
| Max number of LUNs per target. |
| |
| |
| 12. Installation |
| |
| This driver is part of the linux kernel distribution. |
| Driver files are located in the sub-directory "drivers/scsi" of the |
| kernel source tree. |
| |
| Driver files: |
| |
| README.ncr53c8xx : this file |
| ChangeLog.ncr53c8xx : change log |
| ncr53c8xx.h : definitions |
| ncr53c8xx.c : the driver code |
| |
| New driver versions are made available separately in order to allow testing |
| changes and new features prior to including them into the linux kernel |
| distribution. The following URL provides information on latest available |
| patches: |
| |
| ftp://ftp.tux.org/pub/people/gerard-roudier/README |
| |
| |
| 13. Architecture dependent features. |
| |
| <Not yet written> |
| |
| |
| 14. Known problems |
| |
| 14.1 Tagged commands with Iomega Jaz device |
| |
| I have not tried this device, however it has been reported to me the |
| following: This device is capable of Tagged command queuing. However |
| while spinning up, it rejects Tagged commands. This behaviour is |
| conforms to 6.8.2 of SCSI-2 specifications. The current behaviour of |
| the driver in that situation is not satisfying. So do not enable |
| Tagged command queuing for devices that are able to spin down. The |
| other problem that may appear is timeouts. The only way to avoid |
| timeouts seems to edit linux/drivers/scsi/sd.c and to increase the |
| current timeout values. |
| |
| 14.2 Device names change when another controller is added. |
| |
| When you add a new NCR53C8XX chip based controller to a system that already |
| has one or more controllers of this family, it may happen that the order |
| the driver registers them to the kernel causes problems due to device |
| name changes. |
| When at least one controller uses NvRAM, SDMS BIOS version 4 allows you to |
| define the order the BIOS will scan the scsi boards. The driver attaches |
| controllers according to BIOS information if NvRAM detect option is set. |
| |
| If your controllers do not have NvRAM, you can: |
| |
| - Ask the driver to probe chip ids in reverse order from the boot command |
| line: ncr53c8xx=revprob:y |
| - Make appropriate changes in the fstab. |
| - Use the 'scsidev' tool from Eric Youngdale. |
| |
| 14.3 Using only 8 bit devices with a WIDE SCSI controller. |
| |
| When only 8 bit NARROW devices are connected to a 16 bit WIDE SCSI controller, |
| you must ensure that lines of the wide part of the SCSI BUS are pulled-up. |
| This can be achieved by ENABLING the WIDE TERMINATOR portion of the SCSI |
| controller card. |
| The TYAN 1365 documentation revision 1.2 is not correct about such settings. |
| (page 10, figure 3.3). |
| |
| 14.4 Possible data corruption during a Memory Write and Invalidate |
| |
| This problem is described in SYMBIOS DEL 397, Part Number 69-039241, ITEM 4. |
| |
| In some complex situations, 53C875 chips revision <= 3 may start a PCI |
| Write and Invalidate Command at a not cache-line-aligned 4 DWORDS boundary. |
| This is only possible when Cache Line Size is 8 DWORDS or greater. |
| Pentium systems use a 8 DWORDS cache line size and so are concerned by |
| this chip bug, unlike i486 systems that use a 4 DWORDS cache line size. |
| |
| When this situation occurs, the chip may complete the Write and Invalidate |
| command after having only filled part of the last cache line involved in |
| the transfer, leaving to data corruption the remainder of this cache line. |
| |
| Not using Write And Invalidate obviously gets rid of this chip bug, and so |
| it is now the default setting of the driver. |
| However, for people like me who want to enable this feature, I have added |
| part of a work-around suggested by SYMBIOS. This work-around resets the |
| addressing logic when the DATA IN phase is entered and so prevents the bug |
| from being triggered for the first SCSI MOVE of the phase. This work-around |
| should be enough according to the following: |
| |
| The only driver internal data structure that is greater than 8 DWORDS and |
| that is moved by the SCRIPTS processor is the 'CCB header' that contains |
| the context of the SCSI transfer. This data structure is aligned on 8 DWORDS |
| boundary (Pentium Cache Line Size), and so is immune to this chip bug, at |
| least on Pentium systems. |
| But the conditions of this bug can be met when a SCSI read command is |
| performed using a buffer that is 4 DWORDS but not cache-line aligned. |
| This cannot happen under Linux when scatter/gather lists are used since |
| they only refer to system buffers that are well aligned. So, a work around |
| may only be needed under Linux when a scatter/gather list is not used and |
| when the SCSI DATA IN phase is reentered after a phase mismatch. |
| |
| 14.5 IRQ sharing problems |
| |
| When an IRQ is shared by devices that are handled by different drivers, it |
| may happen that one driver complains about the request of the IRQ having |
| failed. Inder Linux-2.0, this may be due to one driver having requested the |
| IRQ using the SA_INTERRUPT flag but some other having requested the same IRQ |
| without this flag. Under both Linux-2.0 and linux-2.2, this may be caused by |
| one driver not having requested the IRQ with the SA_SHIRQ flag. |
| |
| By default, the ncr53c8xx and sym53c8xx drivers request IRQs with both the |
| SA_INTERRUPT and the SA_SHIRQ flag under Linux-2.0 and with only the SA_SHIRQ |
| flag under Linux-2.2. |
| |
| Under Linux-2.0, you can disable use of SA_INTERRUPT flag from the boot |
| command line by using the following option: |
| |
| ncr53c8xx=irqm:0x20 (for the generic ncr53c8xx driver) |
| sym53c8xx=irqm:0x20 (for the sym53c8xx driver) |
| |
| If this does not fix the problem, then you may want to check how all other |
| drivers are requesting the IRQ and report the problem. Note that if at least |
| a single driver does not request the IRQ with the SA_SHIRQ flag (share IRQ), |
| then the request of the IRQ obviously will not succeed for all the drivers. |
| |
| 15. SCSI problem troubleshooting |
| |
| 15.1 Problem tracking |
| |
| Most SCSI problems are due to a non conformant SCSI bus or to buggy |
| devices. If infortunately you have SCSI problems, you can check the |
| following things: |
| |
| - SCSI bus cables |
| - terminations at both end of the SCSI chain |
| - linux syslog messages (some of them may help you) |
| |
| If you do not find the source of problems, you can configure the |
| driver with no features enabled. |
| |
| - only asynchronous data transfers |
| - tagged commands disabled |
| - disconnections not allowed |
| |
| Now, if your SCSI bus is ok, your system have every chance to work |
| with this safe configuration but performances will not be optimal. |
| |
| If it still fails, then you can send your problem description to |
| appropriate mailing lists or news-groups. Send me a copy in order to |
| be sure I will receive it. Obviously, a bug in the driver code is |
| possible. |
| |
| My email address: Gerard Roudier <groudier@free.fr> |
| |
| Allowing disconnections is important if you use several devices on |
| your SCSI bus but often causes problems with buggy devices. |
| Synchronous data transfers increases throughput of fast devices like |
| hard disks. Good SCSI hard disks with a large cache gain advantage of |
| tagged commands queuing. |
| |
| Try to enable one feature at a time with control commands. For example: |
| |
| - echo "setsync all 25" >/proc/scsi/ncr53c8xx/0 |
| Will enable fast synchronous data transfer negotiation for all targets. |
| |
| - echo "setflag 3" >/proc/scsi/ncr53c8xx/0 |
| Will reset flags (no_disc) for target 3, and so will allow it to disconnect |
| the SCSI Bus. |
| |
| - echo "settags 3 8" >/proc/scsi/ncr53c8xx/0 |
| Will enable tagged command queuing for target 3 if that device supports it. |
| |
| Once you have found the device and the feature that cause problems, just |
| disable that feature for that device. |
| |
| 15.2 Understanding hardware error reports |
| |
| When the driver detects an unexpected error condition, it may display a |
| message of the following pattern. |
| |
| sym53c876-0:1: ERROR (0:48) (1-21-65) (f/95) @ (script 7c0:19000000). |
| sym53c876-0: script cmd = 19000000 |
| sym53c876-0: regdump: da 10 80 95 47 0f 01 07 75 01 81 21 80 01 09 00. |
| |
| Some fields in such a message may help you understand the cause of the |
| problem, as follows: |
| |
| sym53c876-0:1: ERROR (0:48) (1-21-65) (f/95) @ (script 7c0:19000000). |
| ............A.........B.C....D.E..F....G.H.......I.....J...K....... |
| |
| Field A : target number. |
| SCSI ID of the device the controller was talking with at the moment the |
| error occurs. |
| |
| Field B : DSTAT io register (DMA STATUS) |
| Bit 0x40 : MDPE Master Data Parity Error |
| Data parity error detected on the PCI BUS. |
| Bit 0x20 : BF Bus Fault |
| PCI bus fault condition detected |
| Bit 0x01 : IID Illegal Instruction Detected |
| Set by the chip when it detects an Illegal Instruction format |
| on some condition that makes an instruction illegal. |
| Bit 0x80 : DFE Dma Fifo Empty |
| Pure status bit that does not indicate an error. |
| If the reported DSTAT value contains a combination of MDPE (0x40), |
| BF (0x20), then the cause may be likely due to a PCI BUS problem. |
| |
| Field C : SIST io register (SCSI Interrupt Status) |
| Bit 0x08 : SGE SCSI GROSS ERROR |
| Indicates that the chip detected a severe error condition |
| on the SCSI BUS that prevents the SCSI protocol from functioning |
| properly. |
| Bit 0x04 : UDC Unexpected Disconnection |
| Indicates that the device released the SCSI BUS when the chip |
| was not expecting this to happen. A device may behave so to |
| indicate the SCSI initiator that an error condition not reportable using the SCSI protocol has occurred. |
| Bit 0x02 : RST SCSI BUS Reset |
| Generally SCSI targets do not reset the SCSI BUS, although any |
| device on the BUS can reset it at any time. |
| Bit 0x01 : PAR Parity |
| SCSI parity error detected. |
| On a faulty SCSI BUS, any error condition among SGE (0x08), UDC (0x04) and |
| PAR (0x01) may be detected by the chip. If your SCSI system sometimes |
| encounters such error conditions, especially SCSI GROSS ERROR, then a SCSI |
| BUS problem is likely the cause of these errors. |
| |
| For fields D,E,F,G and H, you may look into the sym53c8xx_defs.h file |
| that contains some minimal comments on IO register bits. |
| Field D : SOCL Scsi Output Control Latch |
| This register reflects the state of the SCSI control lines the |
| chip want to drive or compare against. |
| Field E : SBCL Scsi Bus Control Lines |
| Actual value of control lines on the SCSI BUS. |
| Field F : SBDL Scsi Bus Data Lines |
| Actual value of data lines on the SCSI BUS. |
| Field G : SXFER SCSI Transfer |
| Contains the setting of the Synchronous Period for output and |
| the current Synchronous offset (offset 0 means asynchronous). |
| Field H : SCNTL3 Scsi Control Register 3 |
| Contains the setting of timing values for both asynchronous and |
| synchronous data transfers. |
| |
| Understanding Fields I, J, K and dumps requires to have good knowledge of |
| SCSI standards, chip cores functionnals and internal driver data structures. |
| You are not required to decode and understand them, unless you want to help |
| maintain the driver code. |
| |
| 16. Synchronous transfer negotiation tables |
| |
| Tables below have been created by calling the routine the driver uses |
| for synchronisation negotiation timing calculation and chip setting. |
| The first table corresponds to Ultra chips 53875 and 53C860 with 80 MHz |
| clock and 5 clock divisors. |
| The second one has been calculated by setting the scsi clock to 40 Mhz |
| and using 4 clock divisors and so applies to all NCR53C8XX chips in fast |
| SCSI-2 mode. |
| |
| Periods are in nano-seconds and speeds are in Mega-transfers per second. |
| 1 Mega-transfers/second means 1 MB/s with 8 bits SCSI and 2 MB/s with |
| Wide16 SCSI. |
| |
| 16.1 Synchronous timings for 53C895, 53C875 and 53C860 SCSI controllers |
| |
| ---------------------------------------------- |
| Negotiated NCR settings |
| Factor Period Speed Period Speed |
| ------ ------ ------ ------ ------ |
| 10 25 40.000 25 40.000 (53C895 only) |
| 11 30.2 33.112 31.25 32.000 (53C895 only) |
| 12 50 20.000 50 20.000 |
| 13 52 19.230 62 16.000 |
| 14 56 17.857 62 16.000 |
| 15 60 16.666 62 16.000 |
| 16 64 15.625 75 13.333 |
| 17 68 14.705 75 13.333 |
| 18 72 13.888 75 13.333 |
| 19 76 13.157 87 11.428 |
| 20 80 12.500 87 11.428 |
| 21 84 11.904 87 11.428 |
| 22 88 11.363 93 10.666 |
| 23 92 10.869 93 10.666 |
| 24 96 10.416 100 10.000 |
| 25 100 10.000 100 10.000 |
| 26 104 9.615 112 8.888 |
| 27 108 9.259 112 8.888 |
| 28 112 8.928 112 8.888 |
| 29 116 8.620 125 8.000 |
| 30 120 8.333 125 8.000 |
| 31 124 8.064 125 8.000 |
| 32 128 7.812 131 7.619 |
| 33 132 7.575 150 6.666 |
| 34 136 7.352 150 6.666 |
| 35 140 7.142 150 6.666 |
| 36 144 6.944 150 6.666 |
| 37 148 6.756 150 6.666 |
| 38 152 6.578 175 5.714 |
| 39 156 6.410 175 5.714 |
| 40 160 6.250 175 5.714 |
| 41 164 6.097 175 5.714 |
| 42 168 5.952 175 5.714 |
| 43 172 5.813 175 5.714 |
| 44 176 5.681 187 5.333 |
| 45 180 5.555 187 5.333 |
| 46 184 5.434 187 5.333 |
| 47 188 5.319 200 5.000 |
| 48 192 5.208 200 5.000 |
| 49 196 5.102 200 5.000 |
| |
| |
| 16.2 Synchronous timings for fast SCSI-2 53C8XX controllers |
| |
| ---------------------------------------------- |
| Negotiated NCR settings |
| Factor Period Speed Period Speed |
| ------ ------ ------ ------ ------ |
| 25 100 10.000 100 10.000 |
| 26 104 9.615 125 8.000 |
| 27 108 9.259 125 8.000 |
| 28 112 8.928 125 8.000 |
| 29 116 8.620 125 8.000 |
| 30 120 8.333 125 8.000 |
| 31 124 8.064 125 8.000 |
| 32 128 7.812 131 7.619 |
| 33 132 7.575 150 6.666 |
| 34 136 7.352 150 6.666 |
| 35 140 7.142 150 6.666 |
| 36 144 6.944 150 6.666 |
| 37 148 6.756 150 6.666 |
| 38 152 6.578 175 5.714 |
| 39 156 6.410 175 5.714 |
| 40 160 6.250 175 5.714 |
| 41 164 6.097 175 5.714 |
| 42 168 5.952 175 5.714 |
| 43 172 5.813 175 5.714 |
| 44 176 5.681 187 5.333 |
| 45 180 5.555 187 5.333 |
| 46 184 5.434 187 5.333 |
| 47 188 5.319 200 5.000 |
| 48 192 5.208 200 5.000 |
| 49 196 5.102 200 5.000 |
| |
| |
| 17. Serial NVRAM (added by Richard Waltham: dormouse@farsrobt.demon.co.uk) |
| |
| 17.1 Features |
| |
| Enabling serial NVRAM support enables detection of the serial NVRAM included |
| on Symbios and some Symbios compatible host adaptors, and Tekram boards. The |
| serial NVRAM is used by Symbios and Tekram to hold set up parameters for the |
| host adaptor and it's attached drives. |
| |
| The Symbios NVRAM also holds data on the boot order of host adaptors in a |
| system with more than one host adaptor. This enables the order of scanning |
| the cards for drives to be changed from the default used during host adaptor |
| detection. |
| |
| This can be done to a limited extent at the moment using "reverse probe" but |
| this only changes the order of detection of different types of cards. The |
| NVRAM boot order settings can do this as well as change the order the same |
| types of cards are scanned in, something "reverse probe" cannot do. |
| |
| Tekram boards using Symbios chips, DC390W/F/U, which have NVRAM are detected |
| and this is used to distinguish between Symbios compatible and Tekram host |
| adaptors. This is used to disable the Symbios compatible "diff" setting |
| incorrectly set on Tekram boards if the CONFIG_SCSI_53C8XX_SYMBIOS_COMPAT |
| configuration parameter is set enabling both Symbios and Tekram boards to be |
| used together with the Symbios cards using all their features, including |
| "diff" support. ("led pin" support for Symbios compatible cards can remain |
| enabled when using Tekram cards. It does nothing useful for Tekram host |
| adaptors but does not cause problems either.) |
| |
| |
| 17.2 Symbios NVRAM layout |
| |
| typical data at NVRAM address 0x100 (53c810a NVRAM) |
| ----------------------------------------------------------- |
| 00 00 |
| 64 01 |
| 8e 0b |
| |
| 00 30 00 00 00 00 07 00 00 00 00 00 00 00 07 04 10 04 00 00 |
| |
| 04 00 0f 00 00 10 00 50 00 00 01 00 00 62 |
| 04 00 03 00 00 10 00 58 00 00 01 00 00 63 |
| 04 00 01 00 00 10 00 48 00 00 01 00 00 61 |
| 00 00 00 00 00 00 00 00 00 00 00 00 00 00 |
| |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 |
| |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 |
| |
| 00 00 00 00 00 00 00 00 |
| 00 00 00 00 00 00 00 00 |
| 00 00 00 00 00 00 00 00 |
| 00 00 00 00 00 00 00 00 |
| 00 00 00 00 00 00 00 00 |
| 00 00 00 00 00 00 00 00 |
| 00 00 00 00 00 00 00 00 |
| 00 00 00 00 00 00 00 00 |
| |
| 00 00 00 00 00 00 00 00 |
| 00 00 00 00 00 00 00 00 |
| 00 00 00 00 00 00 00 00 |
| 00 00 00 00 00 00 00 00 |
| 00 00 00 00 00 00 00 00 |
| 00 00 00 00 00 00 00 00 |
| 00 00 00 00 00 00 00 00 |
| 00 00 00 00 00 00 00 00 |
| |
| 00 00 00 00 00 00 00 00 |
| 00 00 00 00 00 00 00 00 |
| 00 00 00 00 00 00 00 00 |
| |
| fe fe |
| 00 00 |
| 00 00 |
| ----------------------------------------------------------- |
| NVRAM layout details |
| |
| NVRAM Address 0x000-0x0ff not used |
| 0x100-0x26f initialised data |
| 0x270-0x7ff not used |
| |
| general layout |
| |
| header - 6 bytes, |
| data - 356 bytes (checksum is byte sum of this data) |
| trailer - 6 bytes |
| --- |
| total 368 bytes |
| |
| data area layout |
| |
| controller set up - 20 bytes |
| boot configuration - 56 bytes (4x14 bytes) |
| device set up - 128 bytes (16x8 bytes) |
| unused (spare?) - 152 bytes (19x8 bytes) |
| --- |
| total 356 bytes |
| |
| ----------------------------------------------------------- |
| header |
| |
| 00 00 - ?? start marker |
| 64 01 - byte count (lsb/msb excludes header/trailer) |
| 8e 0b - checksum (lsb/msb excludes header/trailer) |
| ----------------------------------------------------------- |
| controller set up |
| |
| 00 30 00 00 00 00 07 00 00 00 00 00 00 00 07 04 10 04 00 00 |
| | | | | |
| | | | -- host ID |
| | | | |
| | | --Removable Media Support |
| | | 0x00 = none |
| | | 0x01 = Bootable Device |
| | | 0x02 = All with Media |
| | | |
| | --flag bits 2 |
| | 0x00000001= scan order hi->low |
| | (default 0x00 - scan low->hi) |
| --flag bits 1 |
| 0x00000001 scam enable |
| 0x00000010 parity enable |
| 0x00000100 verbose boot msgs |
| |
| remaining bytes unknown - they do not appear to change in my |
| current set up for any of the controllers. |
| |
| default set up is identical for 53c810a and 53c875 NVRAM |
| (Removable Media added Symbios BIOS version 4.09) |
| ----------------------------------------------------------- |
| boot configuration |
| |
| boot order set by order of the devices in this table |
| |
| 04 00 0f 00 00 10 00 50 00 00 01 00 00 62 -- 1st controller |
| 04 00 03 00 00 10 00 58 00 00 01 00 00 63 2nd controller |
| 04 00 01 00 00 10 00 48 00 00 01 00 00 61 3rd controller |
| 00 00 00 00 00 00 00 00 00 00 00 00 00 00 4th controller |
| | | | | | | | | |
| | | | | | | ---- PCI io port adr |
| | | | | | --0x01 init/scan at boot time |
| | | | | --PCI device/function number (0xdddddfff) |
| | | ----- ?? PCI vendor ID (lsb/msb) |
| ----PCI device ID (lsb/msb) |
| |
| ?? use of this data is a guess but seems reasonable |
| |
| remaining bytes unknown - they do not appear to change in my |
| current set up |
| |
| default set up is identical for 53c810a and 53c875 NVRAM |
| ----------------------------------------------------------- |
| device set up (up to 16 devices - includes controller) |
| |
| 0f 00 08 08 64 00 0a 00 - id 0 |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 |
| |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 |
| 0f 00 08 08 64 00 0a 00 - id 15 |
| | | | | | | |
| | | | | ----timeout (lsb/msb) |
| | | | --synch period (0x?? 40 Mtrans/sec- fast 40) (probably 0x28) |
| | | | (0x30 20 Mtrans/sec- fast 20) |
| | | | (0x64 10 Mtrans/sec- fast ) |
| | | | (0xc8 5 Mtrans/sec) |
| | | | (0x00 asynchronous) |
| | | -- ?? max sync offset (0x08 in NVRAM on 53c810a) |
| | | (0x10 in NVRAM on 53c875) |
| | --device bus width (0x08 narrow) |
| | (0x10 16 bit wide) |
| --flag bits |
| 0x00000001 - disconnect enabled |
| 0x00000010 - scan at boot time |
| 0x00000100 - scan luns |
| 0x00001000 - queue tags enabled |
| |
| remaining bytes unknown - they do not appear to change in my |
| current set up |
| |
| ?? use of this data is a guess but seems reasonable |
| (but it could be max bus width) |
| |
| default set up for 53c810a NVRAM |
| default set up for 53c875 NVRAM - bus width - 0x10 |
| - sync offset ? - 0x10 |
| - sync period - 0x30 |
| ----------------------------------------------------------- |
| ?? spare device space (32 bit bus ??) |
| |
| 00 00 00 00 00 00 00 00 (19x8bytes) |
| . |
| . |
| 00 00 00 00 00 00 00 00 |
| |
| default set up is identical for 53c810a and 53c875 NVRAM |
| ----------------------------------------------------------- |
| trailer |
| |
| fe fe - ? end marker ? |
| 00 00 |
| 00 00 |
| |
| default set up is identical for 53c810a and 53c875 NVRAM |
| ----------------------------------------------------------- |
| |
| |
| |
| 17.3 Tekram NVRAM layout |
| |
| nvram 64x16 (1024 bit) |
| |
| Drive settings |
| |
| Drive ID 0-15 (addr 0x0yyyy0 = device setup, yyyy = ID) |
| (addr 0x0yyyy1 = 0x0000) |
| |
| x x x x x x x x x x x x x x x x |
| | | | | | | | | | |
| | | | | | | | | ----- parity check 0 - off |
| | | | | | | | | 1 - on |
| | | | | | | | | |
| | | | | | | | ------- sync neg 0 - off |
| | | | | | | | 1 - on |
| | | | | | | | |
| | | | | | | --------- disconnect 0 - off |
| | | | | | | 1 - on |
| | | | | | | |
| | | | | | ----------- start cmd 0 - off |
| | | | | | 1 - on |
| | | | | | |
| | | | | -------------- tagged cmds 0 - off |
| | | | | 1 - on |
| | | | | |
| | | | ---------------- wide neg 0 - off |
| | | | 1 - on |
| | | | |
| --------------------------- sync rate 0 - 10.0 Mtrans/sec |
| 1 - 8.0 |
| 2 - 6.6 |
| 3 - 5.7 |
| 4 - 5.0 |
| 5 - 4.0 |
| 6 - 3.0 |
| 7 - 2.0 |
| 7 - 2.0 |
| 8 - 20.0 |
| 9 - 16.7 |
| a - 13.9 |
| b - 11.9 |
| |
| Global settings |
| |
| Host flags 0 (addr 0x100000, 32) |
| |
| x x x x x x x x x x x x x x x x |
| | | | | | | | | | | | | |
| | | | | | | | | ----------- host ID 0x00 - 0x0f |
| | | | | | | | | |
| | | | | | | | ----------------------- support for 0 - off |
| | | | | | | | > 2 drives 1 - on |
| | | | | | | | |
| | | | | | | ------------------------- support drives 0 - off |
| | | | | | | > 1Gbytes 1 - on |
| | | | | | | |
| | | | | | --------------------------- bus reset on 0 - off |
| | | | | | power on 1 - on |
| | | | | | |
| | | | | ----------------------------- active neg 0 - off |
| | | | | 1 - on |
| | | | | |
| | | | -------------------------------- imm seek 0 - off |
| | | | 1 - on |
| | | | |
| | | ---------------------------------- scan luns 0 - off |
| | | 1 - on |
| | | |
| -------------------------------------- removable 0 - disable |
| as BIOS dev 1 - boot device |
| 2 - all |
| |
| Host flags 1 (addr 0x100001, 33) |
| |
| x x x x x x x x x x x x x x x x |
| | | | | | | |
| | | | --------- boot delay 0 - 3 sec |
| | | | 1 - 5 |
| | | | 2 - 10 |
| | | | 3 - 20 |
| | | | 4 - 30 |
| | | | 5 - 60 |
| | | | 6 - 120 |
| | | | |
| --------------------------- max tag cmds 0 - 2 |
| 1 - 4 |
| 2 - 8 |
| 3 - 16 |
| 4 - 32 |
| |
| Host flags 2 (addr 0x100010, 34) |
| |
| x x x x x x x x x x x x x x x x |
| | |
| ----- F2/F6 enable 0 - off ??? |
| 1 - on ??? |
| |
| checksum (addr 0x111111) |
| |
| checksum = 0x1234 - (sum addr 0-63) |
| |
| ---------------------------------------------------------------------------- |
| |
| default nvram data: |
| |
| 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 |
| 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 |
| 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 |
| 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 0x0037 0x0000 |
| |
| 0x0f07 0x0400 0x0001 0x0000 0x0000 0x0000 0x0000 0x0000 |
| 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 |
| 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 |
| 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0x0000 0xfbbc |
| |
| |
| 18. Support for Big Endian |
| |
| The PCI local bus has been primarily designed for x86 architecture. |
| As a consequence, PCI devices generally expect DWORDS using little endian |
| byte ordering. |
| |
| 18.1 Big Endian CPU |
| |
| In order to support NCR chips on a Big Endian architecture the driver has to |
| perform byte reordering each time it is needed. This feature has been |
| added to the driver by Cort <cort@cs.nmt.edu> and is available in driver |
| version 2.5 and later ones. For the moment Big Endian support has only |
| been tested on Linux/PPC (PowerPC). |
| |
| 18.2 NCR chip in Big Endian mode of operations |
| |
| It can be read in SYMBIOS documentation that some chips support a special |
| Big Endian mode, on paper: 53C815, 53C825A, 53C875, 53C875N, 53C895. |
| This mode of operations is not software-selectable, but needs pin named |
| BigLit to be pulled-up. Using this mode, most of byte reorderings should |
| be avoided when the driver is running on a Big Endian CPU. |
| Driver version 2.5 is also, in theory, ready for this feature. |
| |
| =============================================================================== |
| End of NCR53C8XX driver README file |
