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SYM(4)                 FreeBSD Kernel Interfaces Manual                 SYM(4)

     sym -- NCR/Symbios/LSI Logic 53C8XX PCI SCSI host adapter driver

     To compile this driver into the kernel, place the following lines in your
     kernel configuration file:

           device pci
           device scbus
           device sym

           To disable PCI parity checking (needed for broken bridges):
           options SYM_SETUP_PCI_PARITY=<boolean>

           To control driver probing against HVD buses:
           options SYM_SETUP_SCSI_DIFF=<bit combination>

           To control chip attachment balancing between the ncr driver and
           this driver:
           options SYM_SETUP_LP_PROBE_MAP=<bit combination>

     Alternatively, to load the driver as a module at boot time, place the
     following line in loader.conf(5):


     This driver provides support for the Symbios/LSI Logic 53C8XX PCI SCSI

     Driver features include support for wide SCSI busses and fast10, fast20,
     fast40 and fast80-dt synchronous data transfers depending on controller
     capabilities.  It also provides generic SCSI features such as tagged com-
     mand queueing and auto-request sense.  This driver is configured by
     default for a maximum of 446 outstanding commands per bus, 8 LUNs per
     target and 64 tagged tasks per LUN.  These numbers are not so much lim-
     ited by design as they are considered reasonable values for current SCSI
     technology.  These values can be increased by changing appropriate con-
     stants in driver header files (not recommended).

     This driver supports the entire Symbios 53C8XX family of PCI SCSI con-
     trollers.  It also offers the advantage of architectural improvements
     available only with newer chips.

     sym notably handles phase mismatch from SCRIPTS for the 53C896, 53C895A,
     and 53C1010 cores.  As a result, it guarantees that no more than 1 inter-
     rupt per IO completion is delivered to the CPU, and that the SCRIPTS pro-
     cessor is never stalled waiting for CPU attention in normal situations.

     sym also uses LOAD/STORE SCRIPTS instructions for chips that support it.
     Only the early 810, 815 and 825 NCR chips do not support LOAD/STORE.  Use
     of LOAD/STORE instead of MEMORY MOVE allows SCRIPTS to access IO regis-
     ters internal to the chip (no external PCI cycles).  As a result, the
     driver guarantees that no PCI self-mastering will occur for chips that
     support LOAD/STORE.

     LOAD/STORE instructions are also faster than MEMORY MOVE because they do
     not involve the chip DMA FIFO and are coded on 2 DWORDs instead of 3.

     For the early NCR 810, 815 and 825 chips, the driver uses a separate
     SCRIPTS set that uses MEMORY MOVE instructions for data movements.  This
     is because LOAD/STORE are not supported by these chips.

     HVD/LVD capable controllers (895, 895A, 896, and 897) report the actual
     bus mode in the STEST4 chip IO registers.  This feature allows the driver
     to safely probe against bus mode and to set up the chip accordingly.  By
     default the driver only supports HVD for these chips.  For other chips
     that can support HVD but not LVD, the driver has to probe implementation
     dependent registers (GPIO) in order to detect HVD bus mode.  Only HVD
     implementations that conform with Symbios Logic recommendations can be
     detected by the driver.  When the SYM_SETUP_SCSI_DIFF kernel option is
     assigned a value of 1, the driver will also probe against HVD for 825a,
     875, 876 and 885 chips, assuming Symbios Logic compatible implementation
     of HVD.

     When the SYM_SETUP_PCI_PARITY is assigned a value of 0, the driver will
     not enable PCI parity checking for 53C8XX devices.  PCI parity checking
     should not be an option for PCI SCSI controllers, but some systems have
     been reported to fail using 53C8XX chips, due to spurious or permanent
     PCI parity errors detected.  This option is supplied for convenience but
     it is neither recommended nor supported.

     The generic ncr(4) driver also supports SYM53C8XX based PCI SCSI con-
     trollers, except for the SYM53C1010, which is only supported by the sym

     By default, when both the ncr(4) and sym drivers are configured, the sym
     driver takes precedence over the ncr(4) driver.  The user can indicate a
     balancing of chip types between the two drivers by defining the
     SYM_SETUP_LP_PROBE_MAP kernel configuration option as follows:

     Bit     Devices to be attached by ncr instead
     0x01    53C810a, 53C860
     0x02    53C825a, 53C875, 53C876, 53C885, 53C895
     0x04    53C895a, 53C896, 53C897, 53C1510d
     0x40    53C810, 53C815, 53C825

     For example, if SYM_SETUP_LP_PROBE_MAP is supplied with the value 0x41,
     the ncr(4) driver will attach to 53C810, 53C815, 53C825, 53C810a, and
     53C860 based controllers, and the sym driver will attach to all other
     53C8XX based controllers.

     When only the sym driver is configured, the SYM_SETUP_LP_PROBE_MAP option
     has no effect.  Thus, in this case, the sym driver will attach all 53C8XX
     based controllers present in the system.

     This driver offers other options that are not currently exported to the
     user.  They are defined and documented in the sym_conf.h driver file.
     Changing these options is not recommended unless absolutely necessary.
     Some of these options are planned to be exported through sysctl(3) or an
     equivalent mechanism in a future driver releases and therefore, no com-
     patibility is guaranteed.

     At initialization, the driver tries to detect and read user settings from
     controller NVRAM.  The Symbios/Logic NVRAM layout and the Tekram NVRAM
     layout are currently supported.  If the reading of the NVRAM succeeds,
     the following settings are taken into account and reported to CAM:

     Host settings           Symbios    Tekram
     SCSI parity checking    Y          N
     Host SCSI ident         Y          Y
     Verbose messages        Y          N
     Scan targets hi-lo      Y          N
     Avoid SCSI bus reset    Y          N

     Device settings       Symbios    Tekram
     Synchronous period    Y          Y
     SCSI bus width        Y          Y
     Queue tag enable      Y          Y
     Number of tags        NA         Y
     Disconnect enable     Y          Y
     Scan at boot time     Y          N
     Scan LUN              Y          N

     Devices that are configured as disabled for 'scan' in the NVRAM are not
     reported to CAM at system start-up.  They can be discovered later using
     the `camcontrol rescan' command.

     The table below summarizes the main features and capabilities of the
     NCR/Symbios/LSI Logic 53C8XX family of PCI SCSI controllers.

     Chip          Sync    Width   SRAM   PCI64   Supported
     sym53c810     10MHz   8Bit    N      N       Y
     sym53c810a    10MHz   8Bit    N      N       Y
     sym53c815     10MHz   8Bit    N      N       Y
     sym53c825     10MHz   16Bit   N      N       Y
     sym53c825a    10MHz   16Bit   4KB    N       Y
     sym53c860     20MHz   8Bit    N      N       Y
     sym53c875     20MHz   16Bit   4KB    N       Y
     sym53c876     20MHz   16Bit   4KB    N       Y
     sym53c885     20MHz   16Bit   4KB    N       Y
     sym53c895     40MHz   16Bit   4KB    N       Y
     sym53c895A    40MHz   16Bit   8KB    N       Y
     sym53c896     40MHz   16Bit   8KB    Y       Y
     sym53c897     40MHz   16Bit   8KB    Y       Y
     sym53c1510D   40MHz   16Bit   4KB    Y       Y
     sym53c1010    80MHz   16Bit   8KB    Y       Y

     The sym driver provides support for the following Symbios/LSI Logic PCI
     SCSI controllers:

     +o   53C810
     +o   53C810A
     +o   53C815
     +o   53C825
     +o   53C825A
     +o   53C860
     +o   53C875
     +o   53C876
     +o   53C895
     +o   53C895A
     +o   53C896
     +o   53C897
     +o   53C1000
     +o   53C1000R
     +o   53C1010-33
     +o   53C1010-66
     +o   53C1510D

     The SCSI controllers supported by sym can be either embedded on a mother-
     board, or on one of the following add-on boards:

     +o   ASUS SC-200, SC-896
     +o   Data Technology DTC3130 (all variants)
     +o   DawiControl DC2976UW
     +o   Diamond FirePort (all)
     +o   I-O DATA SC-UPCI (PC-98)
     +o   Logitec LHA-521UA (PC-98)
     +o   NCR cards (all)
     +o   Symbios cards (all)
     +o   Tekram DC390W, 390U, 390F, 390U2B, 390U2W, 390U3D, and 390U3W
     +o   Tyan S1365

     The DEC KZPCA-AA is a rebadged SYM8952U.

     cd(4), da(4), ncr(4), sa(4), scsi(4), camcontrol(8)

     The sym driver appeared in FreeBSD 4.0.

     The sym driver was written by Gerard Roudier and is derived from the
     Linux sym53c8xx driver from the same author.  The sym53c8xx driver is
     derived from the ncr53c8xx driver, which was ported from the FreeBSD
     ncr(4) driver to Linux-1.2.13.  The original ncr(4) driver was written
     for 386BSD and FreeBSD by Wolfgang Stanglmeier and Stefan Esser.

     No known bugs.

FreeBSD 6.2                     August 19, 2004                    FreeBSD 6.2


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