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author | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-17 02:20:36 +0400 |
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committer | Linus Torvalds <torvalds@ppc970.osdl.org> | 2005-04-17 02:20:36 +0400 |
commit | 1da177e4c3f41524e886b7f1b8a0c1fc7321cac2 (patch) | |
tree | 0bba044c4ce775e45a88a51686b5d9f90697ea9d /Documentation/scsi/scsi.txt | |
download | linux-1da177e4c3f41524e886b7f1b8a0c1fc7321cac2.tar.xz |
Linux-2.6.12-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 @@ -0,0 +1,44 @@ +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://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 ** (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. + + +** There is a variant of the st driver for controlling OnStream tape + devices. Its module name is osst.o . + |