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231 lines
4.6 KiB
231 lines
4.6 KiB
4 years ago
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<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
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<HTML
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><HEAD
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><TITLE
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>Simulating a Symmetric Multiprocessor (SMP) Machine</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.79"><LINK
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REL="HOME"
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TITLE="Bochs User Manual"
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HREF="index.html"><LINK
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REL="UP"
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TITLE="Tips and Techniques"
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HREF="howto.html"><LINK
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REL="PREVIOUS"
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TITLE="Mounting a disk image using the loop device"
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HREF="loop-device-usage.html"><LINK
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REL="NEXT"
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TITLE="Setting Up Networking in DLX Linux"
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HREF="dlxlinux-networking.html"></HEAD
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><BODY
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CLASS="SECTION"
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BGCOLOR="#FFFFFF"
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ALINK="#0000FF"
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><DIV
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><TABLE
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SUMMARY="Header navigation table"
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><TR
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><TH
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COLSPAN="3"
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ALIGN="center"
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>Bochs User Manual</TH
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></TR
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><TR
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><TD
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WIDTH="10%"
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ALIGN="left"
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VALIGN="bottom"
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><A
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HREF="loop-device-usage.html"
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ACCESSKEY="P"
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>Prev</A
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></TD
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><TD
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WIDTH="80%"
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ALIGN="center"
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VALIGN="bottom"
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>Chapter 8. Tips and Techniques</TD
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><TD
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WIDTH="10%"
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ALIGN="right"
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VALIGN="bottom"
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><A
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HREF="dlxlinux-networking.html"
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ACCESSKEY="N"
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>Next</A
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></TD
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></TABLE
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><HR
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ALIGN="LEFT"
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WIDTH="100%"></DIV
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><DIV
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CLASS="SECTION"
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><H1
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CLASS="SECTION"
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><A
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NAME="SMP"
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>8.8. Simulating a Symmetric Multiprocessor (SMP) Machine</A
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></H1
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><P
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>Bochs can now simulate an SMP machine when you use "--enable-smp" in the
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configure command. SMP support was added by Bryce Denney, who
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was very interested in watching a multiprocessor operating system work
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at a low level. It should also be helpful to operating system developers
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who are writing SMP drivers, or just for users who want to test drive
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an SMP machine to see what it looks like.</P
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><P
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>Starting with Bochs 2.2.6 you can set up the number of processors in the
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<TT
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CLASS="FILENAME"
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>bochsrc</TT
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>. See <A
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HREF="bochsrc.html#BOCHSOPT-CPU"
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>Section 4.2.2</A
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> how to
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set up the number of processors.</P
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><P
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>It is important to understand that configuring bochs for 4 processors will NOT
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make your single-threaded applications run faster in general! On the contrary,
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it has to spend time simulating idle processors as well as the ones doing your
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task. The point is to simulate an SMP system, not to speed up a uniprocessor
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application.</P
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><P
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>What was required to make SMP work in Bochs?
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<P
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></P
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><UL
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><LI
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><P
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> local APIC on each processor with timer</P
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></LI
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><LI
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><P
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> one I/O APIC model</P
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></LI
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><LI
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><P
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> implement RDTSC (read time stamp counter)</P
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></LI
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><LI
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><P
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> a data structure called the Intel Multiprocessor Configuration
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must be present in BIOS memory space. An SMP-aware operating system probes BIOS
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memory to find the structure, which contains information about how many
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processors, their IDs, interrupt sources, etc. Starting with Bochs 2.2.5 these
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structures are dynamicly created by Bochs.</P
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></LI
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><LI
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><P
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> ACPI support is required to boot SMP system in most of modern
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operating systems. For example WinXP 64 bit require ACPI support even for
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single processor configuration. Still not supported by Bochs. (FIXME)</P
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></LI
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></UL
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></P
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><P
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>What needs to be done to improve SMP support?
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<P
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></P
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><UL
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><LI
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><P
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>debugger support is still limited. For example, you can set breakpoints,
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but you can't specify which processor you want to set the breakpoint for.</P
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></LI
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><LI
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><P
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>test on any possible SMP operating systems. Currently success reported for
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Knoppix 4.0.2 and WinNT 4.0 SMP.</P
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></LI
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><LI
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><P
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>several parts of the APIC model which weren't needed before are not
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implemented yet and cause a panic. If you boot linux 2.4.3 for
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example, it says "panic: cluster model addressing not implemented".</P
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></LI
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><LI
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><P
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>A number of people have suggested using threads to simulate each CPU in
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a different thread. Then on a real SMP machine, the threads can execute
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in parallel. This is a great idea, but it's not done at present.</P
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></LI
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></UL
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></P
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></DIV
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><DIV
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CLASS="NAVFOOTER"
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><HR
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ALIGN="LEFT"
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WIDTH="100%"><TABLE
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SUMMARY="Footer navigation table"
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WIDTH="100%"
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BORDER="0"
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CELLSPACING="0"
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><TR
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><TD
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WIDTH="33%"
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ALIGN="left"
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VALIGN="top"
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><A
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HREF="loop-device-usage.html"
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|
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ACCESSKEY="P"
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|
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>Prev</A
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></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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><A
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HREF="index.html"
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ACCESSKEY="H"
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>Home</A
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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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><A
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HREF="dlxlinux-networking.html"
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ACCESSKEY="N"
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>Next</A
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></TD
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></TR
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><TR
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><TD
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WIDTH="33%"
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ALIGN="left"
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|
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VALIGN="top"
|
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|
|
>Mounting a disk image using the loop device</TD
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><TD
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WIDTH="34%"
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|
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ALIGN="center"
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VALIGN="top"
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><A
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HREF="howto.html"
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ACCESSKEY="U"
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>Up</A
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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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>Setting Up Networking in DLX Linux</TD
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></TR
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></TABLE
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></DIV
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></BODY
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></HTML
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>
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