source: clfs-embedded/BOOK/cross-tools/arm/variables.xml

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<!DOCTYPE sect1 PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
  "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
  <!ENTITY % general-entities SYSTEM "../../general.ent">
  %general-entities;
]>

<sect1 id="ch-cross-tools-variables">
  <?dbhtml filename="variables.html"?>

  <title>Build Variables</title>

  <bridgehead renderas="sect4">Setting Host and Target</bridgehead>

  <para os="a">During the building of the cross-compile tools, you will need to
  set a few variables that will be dependent on your particular needs.
  You will need to select the target triplet for the target architecture,
  the CPU architecture, the CPU floating point hardware
  availability, and (if available) the type of floating point hardware. If you 
  do not know what values can be chosen for each of these, you can use the 
  tables as a reference.</para>

  <para os="a1">If your processor is an ARM9, good choices include: triplet of
  arm-linux-musleabi, ARM arch of armv5t, and float of soft.  ARM9
  processors do not usually have hardware floating point abilities. If your
  processor is a Cortex-A series, which often have hardware floating point
  capability, good choices include: triplet of
  arm-linux-musleabihf, ARM arch of armv7-a, float of hard, and fpu
  of vfpv3-d16.</para>

  <para os="f1">If your target CPU has hardware floating point support (not all
  ARM CPUs do), then set the following CLFS_FLOAT variable to either "hard" or
  "softfp".  Use "softfp" if you need to integrate binaries compiled with
  "soft".  Use "hard" if you don't.  If your target CPU does not have hard
  floating point support, set the following CLFS_FLOAT vairable to
  "soft".</para>

<screen os="f2"><userinput>export CLFS_FLOAT="<replaceable>[hard, softfp, or soft]"</replaceable></userinput></screen>

  <para os="f3">If you chose either "hard" or "softfp" for CLFS_FLOAT, you now
  need to set which floating point hardware is actually included (see table below)
  with your ARM CPU:</para>

<screen os="f4"><userinput>export CLFS_FPU="<replaceable>[fpu version]</replaceable>"</userinput></screen>

  <table os="j">
    <title>ARM Hard Floating Point Versions</title>
    <?dbfo table-width="4in" ?>

    <tgroup cols="4">

      <colspec colnum="1" colwidth="1in" colname="FPU Choice"/>
      <colspec colnum="2" colwidth="1in" colname="FPU Choice"/>
      <colspec colnum="3" colwidth="1in" colname="FPU Choice"/>
      <colspec colnum="4" colwidth="1in" colname="FPU Choice"/>

      <tbody>
        <row>
          <entry>fpa</entry>
          <entry>fpe2</entry>
          <entry>fpe3</entry>
          <entry>maverick</entry>
        </row>
        <row>
          <entry>vfp</entry>
          <entry>vfpv3</entry>
          <entry>vfpv3-fp16</entry>
          <entry>vfpv3-d16</entry>
        </row>
        <row>
          <entry>vfpv3-d16-fp16</entry>
          <entry>vfpv3xd</entry>
          <entry>vfpv3xd-fp16</entry>
          <entry>neon</entry>
        </row>
        <row>
          <entry>neon-fp16</entry>
          <entry>vfpv4</entry>
          <entry>vfpv4-d16</entry>
          <entry>fpv4-sp-d16</entry>
        </row>
        <row>
          <entry>neon-vfpv4</entry>
        </row>
      </tbody>
    </tgroup>
  </table>

  <para os="a2">Then, set the host and target triplets:</para>

  <xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
  href="../common/variables.xml"
  xpointer="xpointer(//*[@os='b'])"/>

  <table os="i">
    <title>Target Triplets</title>
    <?dbfo table-width="7in" ?>

    <tgroup cols="2">

      <colspec colnum="1" colwidth="2.5in" colname="Float Type"/>
      <colspec colnum="2" colwidth="2.5in" colname="Triplet"/>

      <thead>
        <row>
          <entry>Float Type</entry>
          <entry>Triplet</entry>
        </row>
      </thead>

      <tbody>
        <row>
          <entry>soft or softfp</entry>
          <entry>arm-linux-musleabi</entry>
        </row>
        <row>
          <entry>hard</entry>
          <entry>arm-linux-musleabihf</entry>
        </row>
      </tbody>

    </tgroup>

  </table>

  <para os="c">Now set the architecture of the CPU:</para>

<screen os="d"><userinput>export CLFS_ARCH=arm</userinput></screen>

  <para os="e">Choose the ARM architecture (see table below):</para>

<screen os="f"><userinput>export CLFS_ARM_ARCH="<replaceable>[architecture]</replaceable>"</userinput></screen>

  <table os="j">
    <title>ARM Archiecture Choices</title>
    <?dbfo table-width="4in" ?>

    <tgroup cols="4">

      <colspec colnum="1" colwidth="1in" colname="Arch Choice"/>
      <colspec colnum="2" colwidth="1in" colname="Arch Choice"/>
      <colspec colnum="3" colwidth="1in" colname="Arch Choice"/>
      <colspec colnum="4" colwidth="1in" colname="Arch Choice"/>

      <tbody>
        <row>
          <entry>armv4t</entry>
          <entry>armv5</entry>
          <entry>armv5t</entry>
          <entry>armv5te</entry>
        </row>
        <row>
          <entry>armv6</entry>
          <entry>armv6j</entry>
          <entry>armv6t2</entry>
          <entry>armv6z</entry>
        </row>
        <row>
          <entry>armv6zk</entry>
          <entry>armv6-m</entry>
          <entry>armv7</entry>
          <entry>armv7-a</entry>
        </row>
        <row>
          <entry>armv7-r</entry>
          <entry>armv7-m</entry>
        </row>
      </tbody>
    </tgroup>
  </table>

  <xi:include xmlns:xi="http://www.w3.org/2003/XInclude"
  href="../common/variables.xml"
  xpointer="xpointer(//*[@os='g'])"/>

<screen os="h"><userinput>echo export CLFS_HOST=\""${CLFS_HOST}\"" &gt;&gt; ~/.bashrc
echo export CLFS_TARGET=\""${CLFS_TARGET}\"" &gt;&gt; ~/.bashrc
echo export CLFS_ARCH=\""${CLFS_ARCH}\"" &gt;&gt; ~/.bashrc
echo export CLFS_ARM_ARCH=\""${CLFS_ARM_ARCH}\"" &gt;&gt; ~/.bashrc
echo export CLFS_FLOAT=\""${CLFS_FLOAT}\"" &gt;&gt; ~/.bashrc
echo export CLFS_FPU=\""${CLFS_FPU}\"" &gt;&gt; ~/.bashrc</userinput></screen>

</sect1>