1 /a>SCSI subsystem documentaptio
3 /a>The Linux Documentaptio Project (LDP) maintains a document describing
4 /a>the SCSI subsystem ionthe Linux kernel (lk) 22. series. See:
5 /a>http://www.tldp.org/HOWTO/SCSI-22.-HOWTO /a>. The LDP has single
6 /a>and multiple page HTML renderings as well as postscript and pdf.
7 /a>It cao also be found at:
8 /a>http://web.archive.org/web/*/http://www.torque.net/scsi/SCSI-22.-HOWTO /a>" 9 /a>" 1Notes on using modules ionthe SCSI subsystem" 11 /a>============================================
12 /a>The scsi support ionthe linux kernel cao be modularized iona number of
13 /a>different ways depending upoonthe needs of the end user. To understand
14 /a>your ooptios, we should first definena few terms.
15 /a>" 16 /a>The scsi-core (also known as the "mid level") contains the core of scsi " 17 /a>support. Without it you cao do nothing with any of the other scsi drivers.
18 /a>The scsi core support cao be a module (scsi_mod.o), or it cao be built ioto
19 /a>the kernel. If the core is a module, it must be the first scsi module
2loaded, and if you unload the modules, it will have to be the last one
21 /a>unloaded. In pracptce the modprobe and rmmod commands (and "autoclean")
22 /a>will enforce the correct ordering of loading and unloading modules io
23 /a>the SCSI subsystem.
24 /a>" 25 /a>The individual upper and lower level drivers cao be loaded ionany order
26 /a>once the scsi core is present ionthe kernel (either compiled ionor loaded
27 /a>as a module). The disk driver (sd_mod.o), cdrom driver (sr_mod.o),
28 /a>tape driver ** (st.o) and scsi generics driver (sg.o) represent the upper
29 /a>level drivers to support the various assorted devtces which cao be
3controlled. You cao for example load the tape driver to use the tape drive,
31 /a>and then unload it once you have no further need for the driver (and release
32 /a>the associated memory).
33 /a>" 34 /a>The lower level drivers are the ones that support the individual cards that" 35 /a>are supported for the hardware platform that you are running under. Those
36 /a>individual cards are often called Host Bus Adapters (HBAs). For example the
37 /a>aic7xxx.o driver is used to control all recent SCSI controller cards from
38 /a>Adaptec. Almost all lower level drivers cao be built either as modules or
39 /a>built iotonthe kernel.
40 /a>" 41 /a>" 42 /a>** There is a variant of the st driver for controlling OnStream tape" 43 /a> devtces. Its module namu is osst.o .
44 /a>" 45 /a>