diff options
author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-16 18:20:36 -0400 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /Documentation/scsi/scsi.txt |
Linux-2.6.12-rc2v2.6.12-rc2
Initial git repository build. I'm not bothering with the full history,
even though we have it. We can create a separate "historical" git
archive of that later if we want to, and in the meantime it's about
3.2GB when imported into git - space that would just make the early
git days unnecessarily complicated, when we don't have a lot of good
infrastructure for it.
Let it rip!
Diffstat (limited to 'Documentation/scsi/scsi.txt')
-rw-r--r-- | Documentation/scsi/scsi.txt | 44 |
1 files changed, 44 insertions, 0 deletions
diff --git a/Documentation/scsi/scsi.txt b/Documentation/scsi/scsi.txt new file mode 100644 index 000000000000..dd1bbf4e98e3 --- /dev/null +++ b/Documentation/scsi/scsi.txt | |||
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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 http://www.torque.net/scsi/SCSI-2.4-HOWTO . | ||
8 | |||
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 . | ||
44 | |||