1.Dd August 27, 1993 2.Dt SD 4 3.Os FreeBSD 4.Sh NAME 5.Nm scsi 6.Nd scsi system 7.Sh SYNOPSIS 8.Nm device-driver scbus 9.Sh DESCRIPTION 10The 11.Em scsi 12system provides a uniform and modular system for the implimentation 13of drivers to control various scsi devices, and to utilise different 14scsi adapters through adapter drivers. When the system probes the 15.Em SCSI 16busses, it attaches any devices it finds to the appropriate 17drivers. If no driver seems appropriate, then at attaches the device to the 18uk (unknown) driver (if configured), so that user level scsi ioctls may 19still be performed against the device. 20.Sh KERNEL CONFIGURATION 21Continuously changing. check your nearest bsd mailing list. 22The option SCSIDEBUG enables the debug ioctl. 23.Sh IOCTLS 24There are a number of ioctls that will (when the next stage is complete) 25work on any 26.Em SCSI 27device. They are defined in 28.Em sys/scsiio.h 29and can be applied against any scsi device that allows both read and write, 30though for devices such as tape, it must be applied against the control 31device. See the manual page for each device type for more information about 32how generic scsi ioctls may be applied to a specific device. 33.Bl -tag -width DIOCSDINFO____ 34.It Dv SCIOCRESET* 35reset a device. 36.It Dv SCIOCDEBUG 37Turn on debugging.. All scsi operations originating from this device's driver 38will be traced to the console, along with other information. Debugging is 39controlled by four bits, described in the header file. If no debugging is 40configured into the kernel, debugging will have no effect. 41.Em SCSI 42debugging is controlled by the configuration option 43.Em SCSIDEBUG. 44.It Dv SCIOCCOMMAND 45Take a scsi command and data from a user process and apply them to the scsi 46device. Return all status information and return data to the process. The 47ioctl will return a successful status even if the device rejected the 48command. As all status is returned to the user, it is up to the user 49process to examine this information to decide the success of the command. 50.It Dv SCIOCREPROBE 51Ask the system to probe the scsi busses for any new devices. If it finds 52any, they will be attached to the appropriate drivers. The search can be 53narrowed to a specific bus, target or lun. The new device may or may not 54be related to the device on which the ioctl was performed. 55.It Dv SCIOCIDENTIFY 56Ask the driver what it's bus, target and lun are. 57.It Dv SCIOCDECONFIG 58Ask the device to dissappear. This may not happen if the device is in use. 59.El 60.Sh NOTES 61the generic scsi part of the system is still being mapped out. 62Watch this space for changes. 63.Pp 64 A device by the name of su (scsi_user) 65(e.g su0-0-0) will map bus, target and lun to minor numbers. I have not 66yet decided yet whether this device will be able to open a device that is 67already controlled by an explicit driver. 68.Sh ADAPTERS 69The system allows common device drivers to work through many different 70types of adapters. The adapters take requests from the upper layers and do 71all IO between the 72.Em SCSI 73bus and the system. The maximum size of a transfer is governed by the 74adapter. Most adapters can transfer 64KB in a single operation, however 75many can transfer larger amounts. 76.Sh TARGET MODE 77Some adapters support 78.Em Target mode 79in which the system is capable of operating as a device, responding to 80operations initioated by another system. Target mode will be supported for 81some adapters, but is not yet complete for this version of the scsi system. 82.Sh FILES 83see other scsi device entries. 84.Sh DIAGNOSTICS 85When the kernel is compiled with option SCSIDEBUG, the SCIOCDEBUG ioctl 86can be used to enable various amounts of tracing information on any 87specific device. Devices not being traced will not produce trace information. 88The four bits that make up the debug level, each control certain types 89of debugging information. 90.Bl -tag -width THIS_WIDE_PLEASE 91.It Dv Bit 0 92Bit 0 shows all scsi bus operations including scsi commands, 93error information and the first 48 bytes of any data transferred. 94.It Dv Bit 1 95Bit 1 shows routines called. 96.It Dv Bit 2 97Bit 2 shows information about what branches are taken and often some 98of the return values of functions. 99.It Dv Bit 3 100Bit 3 shows more detailed information including DMA scatter-gather logs. 101.El 102.Sh SEE ALSO 103.Xr ch 4 104.Xr cd 4 105.Xr sd 4 106.Xr st 4 107.Xr uk 4 108.Xr su 4 109.Xr aha 4 110.Xr ahb 4 111.Xr bt 4 112.Xr uha 4 113.Sh HISTORY 114This 115.Nm 116system appeared in MACH 2.5 at TRW. 117 118