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<?xml version="1.0"?>
<guide self="archs/alpha/">
<chapter>
<title>Arch Specific Notes -- Alpha</title>
<body>
<p>
The Alpha port uses the <c>alpha</c> keyword. It focuses upon HP (formerly Compaq
(formerly DEC)) hardware. This covers from <c>ev4</c> (known as 21064) through
<c>ev7z</c> (known as 21364a).
</p>
<section>
<title>Alpha Kernel and Userland ABIs</title>
<body>
<p>
All Alpha systems use a pure 64 bit kernel and a pure 64 bit userland.
</p>
<p>
All Alpha systems support both little and big endian <d/> however, Linux only uses
little endian.
</p>
</body>
</section>
<section>
<title>Additional Alpha Keywording Requirements</title>
<body>
<p>
It is generally expected that anyone who does keywording for Alpha should be on
the <c>alpha@</c> alias. However the Alpha team is happy if maintainers keyword
their packages when they have access to Alpha hardware, although the team would
like to know about it.
</p>
</body>
</section>
<section>
<title>Alpha Instruction Set and Performance Notes</title>
<body>
<p>
There are six basic Alpha instructions set standards:
</p>
<ul>
<li>
<c>ev4</c> or <c>ev45</c>. The <c>ev4</c> was the first Alpha processor of the Alpha
family. It featured one integer pipeline and one floating-point pipeline.
The <c>ev45</c> is a modified <c>ev4</c> with double both Data and Instruction cache
(D-Cache and I-Cache respectively); it also featured a division optimization.
</li>
<li>
<c>ev5</c> is an evolution of the <c>ev45</c>. The number of pipelines was doubled
and the floating-point pipelines run in 9 stages rather than in 10. The
<c>ev5</c> supports 3 cache levels.
</li>
<li>
<c>ev56</c> added the BWX extension to load/store data in 8 or 16 bit quanta.
</li>
<li>
<c>pca56</c> added a new set, MVI (Motion Video Instructions), aimed to
accelerate video and audio calculations.
</li>
<li>
<c>ev6</c> supports all extensions supported by the <c>pca56</c> and a new set, FIX,
meant to move data between integer and floating-point registers and for square
root.
</li>
<li>
<c>ev67</c> is an evolution of the <c>ev6</c>, in addition it supports a new set.
CIX adds instructions for counting and finding bits.
</li>
</ul>
<p>
When no <c>-mcpu</c> option is passed to <c>gcc</c> it defaults to the processor on
which the compiler was built.
</p>
<p>
The <c>-mieee</c> flag <b>should</b> always be used unless you have a deep knowledge
of the Alpha architecture, so the comments on
<uri link="::general-concepts/user-environment#Not Filtering Variables"/> are
really important on Alpha.
</p>
</body>
</section>
<section>
<title>Notes on Alpha and PIC</title>
<body>
<p>
General <uri link="::general-concepts/pic/"/> policy also applies to Alpha. In fact,
Alpha systems complain loudly if you try to link PIC and non-PIC code. Usually
this results in errors during the compilation aborting emerge.
</p>
</body>
</section>
<section>
<title>Contacting the Alpha Team</title>
<body>
<p>
The Alpha team can be contacted:
</p>
<ul>
<li>
Via Bugzilla bugs assigned to <c>alpha@</c>
</li>
<li>
Via email to the <c>alpha@</c> email alias
</li>
<li>
Via email to the <c>gentoo-alpha</c> mailing list
</li>
<li>
Via the <c>#gentoo-alpha</c> IRC channel on Freenode
</li>
</ul>
</body>
</section>
<section>
<title>Other Resources</title>
<body>
<ul>
<li>
<uri link="http://alpha.gentoo.org/">Gentoo Linux Alpha Development Project</uri>
</li>
<li>
<uri link="http://www.gentoo.org/doc/en/gentoo-alpha-faq.xml">Gentoo/Alpha FAQ</uri>
</li>
<li>
<uri link="http://www.gentoo.org/proj/en/base/alpha/doc/alpha-porting-guide.xml">Alpha Porting Guide</uri>
</li>
<li>
<uri link="http://forums.gentoo.org/viewforum-f-32.html">Gentoo on Alternative Architectures Forum</uri>
</li>
</ul>
</body>
</section>
</body>
</chapter>
</guide>
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