196 lines
3.4 KiB
HTML
196 lines
3.4 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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>Linux and assembly</TITLE
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><META
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NAME="GENERATOR"
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CONTENT="Modular DocBook HTML Stylesheet Version 1.7"><LINK
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REL="HOME"
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TITLE="Linux Assembly HOWTO"
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HREF="index.html"><LINK
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REL="UP"
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TITLE="Do you need assembly?"
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HREF="doyouneed.html"><LINK
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REL="PREVIOUS"
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TITLE="How to NOT use Assembly"
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HREF="howtonot.html"><LINK
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REL="NEXT"
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TITLE="Assemblers"
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HREF="assemblers.html"></HEAD
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><BODY
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CLASS="section"
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BGCOLOR="#FFFFFF"
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TEXT="#000000"
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LINK="#0000FF"
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VLINK="#840084"
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ALINK="#0000FF"
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><DIV
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CLASS="NAVHEADER"
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><TABLE
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SUMMARY="Header 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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><TH
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COLSPAN="3"
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ALIGN="center"
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>Linux Assembly HOWTO</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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>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 2. Do you need assembly?</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="assemblers.html"
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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="AEN246"
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></A
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>2.3. Linux and assembly</H1
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><P
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> As you probably noticed, in general case you don't need to use assembly
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language in Linux programming. Unlike DOS, you do not have to write Linux
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drivers in assembly (well, actually you can do it if you really want). And
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with modern optimizing compilers, if you care of speed optimization for
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different CPU's, it's much simpler to write in C. However, if you're reading
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this, you might have some reason to use assembly instead of C/C++.
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</P
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><P
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> You may <EM
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>need</EM
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> to use assembly, or you may
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<EM
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>want</EM
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> to use assembly. In short, main practical
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(<EM
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>need</EM
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>) reasons of diving into the assembly realm are
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<EM
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>small code</EM
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> and <EM
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><SPAN
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CLASS="application"
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>libc</SPAN
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>
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independence</EM
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>. Impractical (<EM
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>want</EM
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>), and the most
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often reason is being just an old crazy hacker, who has twenty years old habit
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of doing everything in assembly language.
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</P
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><P
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> However, if you're porting Linux to some embedded hardware you can be quite
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short at the size of whole system: you need to fit kernel,
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<SPAN
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CLASS="application"
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>libc</SPAN
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> and all that stuff of
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<SPAN
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CLASS="application"
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>(file|find|text|sh|etc.) utils</SPAN
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> into several hundreds
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of kilobytes, and every kilobyte costs much. So, one of the possible ways is to
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rewrite some (or all) parts of system in assembly, and this will really save
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you a lot of space. For instance, a simple <B
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CLASS="command"
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>httpd</B
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> written in
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assembly can take less than 600 bytes; you can fit a server consisting of
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kernel, httpd and ftpd in 400 KB or less... Think about it.
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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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><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="howtonot.html"
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ACCESSKEY="P"
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>Prev</A
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></TD
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WIDTH="34%"
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VALIGN="top"
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HREF="index.html"
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>Home</A
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ALIGN="right"
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VALIGN="top"
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HREF="assemblers.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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VALIGN="top"
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>How to NOT use Assembly</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="doyouneed.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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>Assemblers</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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> |