214 lines
3.6 KiB
HTML
214 lines
3.6 KiB
HTML
<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN">
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<HTML
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><HEAD
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><TITLE
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>Mid Level, Unifying layer</TITLE
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NAME="GENERATOR"
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TITLE="Proc pseudo file system"
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HREF="procfs.html"><LINK
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REL="NEXT"
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TITLE="boot parameters"
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HREF="mlbparams.html"></HEAD
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><TR
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COLSPAN="3"
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>The Linux 2.4 SCSI subsystem HOWTO</TH
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><TD
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WIDTH="10%"
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ALIGN="left"
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><DIV
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CLASS="chapter"
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><H1
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><A
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NAME="mlevel"
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></A
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>Chapter 8. Mid Level, Unifying layer</H1
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><DIV
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CLASS="TOC"
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><DL
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><DT
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><B
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>Table of Contents</B
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></DT
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><DT
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>8.1. <A
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HREF="mlbparams.html"
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>boot parameters</A
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></DT
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><DT
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>8.2. <A
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HREF="mlmparams.html"
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>module parameters</A
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></DT
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><DT
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>8.3. <A
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HREF="mlproc.html"
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>proc interface</A
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></DT
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></DL
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></DIV
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><P
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> The SCSI mid level is common to all usage of the SCSI subsystem. Probably
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its most important role is to define internal interfaces and services that
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are used by all other SCSI drivers. These internal mechanisms are not
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discussed in this document [see ref: <A
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HREF="refs.html#W2"
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>W2</A
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>].
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</P
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><P
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> The primary kernel configuration parameter "CONFIG_SCSI" determines whether
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the mid level is built in (when "=y") or a module (when "=m"). If
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"CONFIG_SCSI=m" then all other SCSI subsystem drivers must also be modules.
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</P
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><P
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> When the mid level is built as a module then it probably never needs to be
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loaded explicitly because using 'modprobe' to load any other SCSI subsystem
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module will cause the mid level to be loaded first (if it is not already).
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</P
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><P
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> Some upper and lower level drivers do not (fully) load if there are no
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devices for that driver to control. Sometimes the report is loud as in
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this case for the imm driver which controls zip drives connected to a
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parallel port:
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<TABLE
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BORDER="0"
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BGCOLOR="#E0E0E0"
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WIDTH="100%"
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><TR
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><TD
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><FONT
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COLOR="#000000"
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><PRE
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CLASS="programlisting"
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> $ modprobe imm
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imm.o: init_module: No such device
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</PRE
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></FONT
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></TD
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></TR
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></TABLE
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>
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<B
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CLASS="command"
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>lsmod</B
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> will not show the "imm" module as loaded.
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In other cases the result is more subtle. For example, if the sg driver
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is loaded in a system with no (real or pseudo) scsi devices then the
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<TT
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CLASS="filename"
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>/proc/scsi/sg</TT
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> directory will not appear. [It will
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be created when the first scsi device is recognized.]
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</P
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></DIV
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CLASS="NAVFOOTER"
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>Prev</A
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>Home</A
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>Next</A
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VALIGN="top"
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>Proc pseudo file system</TD
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><TD
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WIDTH="34%"
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ALIGN="center"
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VALIGN="top"
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> </TD
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><TD
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WIDTH="33%"
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ALIGN="right"
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VALIGN="top"
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>boot parameters</TD
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></TR
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> |