mirror of
https://github.com/torvalds/linux.git
synced 2024-12-23 03:11:46 +00:00
b7223d9bde
Link: https://lore.kernel.org/r/c617b37769a82901def0fed3d236a25995c4e160.1583136624.git.mchehab+huawei@kernel.org Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org> Signed-off-by: Martin K. Petersen <martin.petersen@oracle.com>
48 lines
2.3 KiB
ReStructuredText
48 lines
2.3 KiB
ReStructuredText
.. SPDX-License-Identifier: GPL-2.0
|
|
|
|
============================
|
|
SCSI subsystem documentation
|
|
============================
|
|
|
|
The Linux Documentation Project (LDP) maintains a document describing
|
|
the SCSI subsystem in the Linux kernel (lk) 2.4 series. See:
|
|
http://www.tldp.org/HOWTO/SCSI-2.4-HOWTO . The LDP has single
|
|
and multiple page HTML renderings as well as postscript and pdf.
|
|
It can also be found at:
|
|
http://web.archive.org/web/%2E/http://www.torque.net/scsi/SCSI-2.4-HOWTO
|
|
|
|
Notes on using modules in the SCSI subsystem
|
|
============================================
|
|
The scsi support in the linux kernel can be modularized in a number of
|
|
different ways depending upon the needs of the end user. To understand
|
|
your options, we should first define a few terms.
|
|
|
|
The scsi-core (also known as the "mid level") contains the core of scsi
|
|
support. Without it you can do nothing with any of the other scsi drivers.
|
|
The scsi core support can be a module (scsi_mod.o), or it can be built into
|
|
the kernel. If the core is a module, it must be the first scsi module
|
|
loaded, and if you unload the modules, it will have to be the last one
|
|
unloaded. In practice the modprobe and rmmod commands (and "autoclean")
|
|
will enforce the correct ordering of loading and unloading modules in
|
|
the SCSI subsystem.
|
|
|
|
The individual upper and lower level drivers can be loaded in any order
|
|
once the scsi core is present in the kernel (either compiled in or loaded
|
|
as a module). The disk driver (sd_mod.o), cdrom driver (sr_mod.o),
|
|
tape driver [1]_ (st.o) and scsi generics driver (sg.o) represent the upper
|
|
level drivers to support the various assorted devices which can be
|
|
controlled. You can for example load the tape driver to use the tape drive,
|
|
and then unload it once you have no further need for the driver (and release
|
|
the associated memory).
|
|
|
|
The lower level drivers are the ones that support the individual cards that
|
|
are supported for the hardware platform that you are running under. Those
|
|
individual cards are often called Host Bus Adapters (HBAs). For example the
|
|
aic7xxx.o driver is used to control all recent SCSI controller cards from
|
|
Adaptec. Almost all lower level drivers can be built either as modules or
|
|
built into the kernel.
|
|
|
|
.. [1] There is a variant of the st driver for controlling OnStream tape
|
|
devices. Its module name is osst.o .
|
|
|