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Based on kernel version 3.16. Page generated on 2014-08-06 21:41 EST.

1	SCSI subsystem documentation
2	============================
3	The Linux Documentation Project (LDP) maintains a document describing
4	the SCSI subsystem in the Linux kernel (lk) 2.4 series. See:
5	http://www.tldp.org/HOWTO/SCSI-2.4-HOWTO . The LDP has single
6	and multiple page HTML renderings as well as postscript and pdf.
7	It can also be found at:
8	http://web.archive.org/web/*/http://www.torque.net/scsi/SCSI-2.4-HOWTO
9	
10	Notes on using modules in the SCSI subsystem
11	============================================
12	The scsi support in the linux kernel can be modularized in a number of 
13	different ways depending upon the needs of the end user.  To understand
14	your options, we should first define a few terms.
15	
16	The scsi-core (also known as the "mid level") contains the core of scsi 
17	support.  Without it you can do nothing with any of the other scsi drivers.
18	The scsi core support can be a module (scsi_mod.o), or it can be built into
19	the kernel. If the core is a module, it must be the first scsi module 
20	loaded, and if you unload the modules, it will have to be the last one 
21	unloaded.  In practice the modprobe and rmmod commands (and "autoclean")
22	will enforce the correct ordering of loading and unloading modules in
23	the SCSI subsystem.
24	
25	The individual upper and lower level drivers can be loaded in any order 
26	once the scsi core is present in the kernel (either compiled in or loaded
27	as a module).  The disk driver (sd_mod.o), cdrom driver (sr_mod.o),
28	tape driver ** (st.o) and scsi generics driver (sg.o) represent the upper 
29	level drivers to support the various assorted devices which can be 
30	controlled.  You can for example load the tape driver to use the tape drive, 
31	and then unload it once you have no further need for the driver (and release
32	the associated memory).
33	
34	The lower level drivers are the ones that support the individual cards that
35	are supported for the hardware platform that you are running under. Those
36	individual cards are often called Host Bus Adapters (HBAs). For example the
37	aic7xxx.o driver is used to control all recent SCSI controller cards from 
38	Adaptec. Almost all lower level drivers can be built either as modules or 
39	built into the kernel.
40	
41	
42	** There is a variant of the st driver for controlling OnStream tape
43	   devices. Its module name is osst.o .
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