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<!-- retain these comments for translator revision tracking -->
<!-- $Id$ -->
<sect2 arch="arm"><title>CPU, Main Boards, and Video Support</title>
<para>
ARM systems are a lot more heterogenous than the i386/amd64-based PC
architecture, where all systems share a common system firmware (BIOS or/and
UEFI) which handles the board-specific basic hardware initialization in a
standardized way.
The ARM architecture is used mainly in so-called <quote>systems-on-chip</quote> (SOCs).
These SOCs are designed by many different companies with vastly varying
hardware components even for the very basic functionality required to bring
the system up. Systems using them usually lack a common system firmware
interface and as a result, on ARM systems the Linux kernel has to take care
of many system-specific low-level issues which are handled by the
mainboard's BIOS in the PC world.
</para>
<para>
At the beginning of the ARM support in the Linux kernel, this resulted in
the requirement of having a seperate kernel for each ARM system in contrast
to the <quote>one-fits-all</quote> kernel for PC systems. As this approach does not
scale to a large number of different systems, work has started to be able to
provide a single ARM kernel that can run on different ARM systems. Support
for newer ARM systems gets implemented in a way that allows the use of such
a multiplatform kernel, but for several older systems a seperate specific
kernel is still required.
Because of this, the standard &debian; distribution only supports
installation on a selected number of older ARM systems in addition to the
newer systems which are supported by the ARM multiplatform (armmp) kernel.
</para>
<para>
The ARM architecture has evolved over time and modern ARM processors provide
features which are not available in older models. &debian; therefore
provides two ARM ports, the &debian;/armel and the &debian;/armhf port.
&debian;/armel targets older ARM processors without support for a hardware
floating point unit (FPU), while &debian;/armhf works only on newer ARM
processors which implement at least the ARMv7 architecture with version 3 of
the ARM vector floating point specification (VFPv3). &debian;/armhf makes
use of the extended features and performance enhancements available on
these models.
</para>
<!--
<para>
While it is technically possible to run the &debian;/armel userland programs
on modern ARM processors, they cannot make use of several
performance-enhancing features of the newer processors, so if your hardware
fulfills the requirements of running the &debian;/armhf port, you should use
it instead of the &debian;/armel port. Mixing of armel and armhf packages
on the same system is not possible, so you have to decide which port to use
before installing the system.
</para>
-->
<para>
Technically, several ARM CPUs can be run in either endian mode (big or little),
but in practice the vast majority of currently available systems
uses little-endian mode. Both &debian;/armhf and &debian;/armel support
only little-endian systems.
</para>
<sect3 arch="arm"><title>Platforms supported by Debian/armel</title>
<para>
The following platforms are supported by &debian;/armel; they require
platform-specific kernels.
<variablelist>
<varlistentry>
<term>Kirkwood</term>
<listitem><para>
Kirkwood is a system on a chip (SoC) from Marvell that integrates an ARM
CPU, Ethernet, SATA, USB, and other functionality in one chip. We
currently support the following Kirkwood based devices: OpenRD
(OpenRD-Base, OpenRD-Client and OpenRD-Ultimate), <ulink
url="&url-arm-cyrius-sheevaplug;">plug computers (SheevaPlug, GuruPlug and
DreamPlug)</ulink>, <ulink url="&url-arm-cyrius-qnap-kirkwood;">QNAP
Turbo Station</ulink> (all TS-11x, TS-21x and TS-41x models), and LaCie
NASes (Network Space v2, Network Space Max v2, Internet Space v2, d2
Network v2, 2Big Network v2 and 5Big Network v2).
</para></listitem>
</varlistentry>
<varlistentry>
<term>Orion5x</term>
<listitem><para>
Orion is a system on a chip (SoC) from Marvell that integrates an ARM CPU,
Ethernet, SATA, USB, and other functionality in one chip. There are many
Network Attached Storage (NAS) devices on the market that are based on an
Orion chip. We currently support the following Orion based devices: <ulink
url="&url-arm-cyrius-kuroboxpro;">Buffalo Kurobox</ulink>, <ulink
url="&url-arm-cyrius-dns323;">D-Link DNS-323</ulink> and <ulink
url="&url-arm-cyrius-mv2120;">HP mv2120</ulink>.
</para></listitem>
</varlistentry>
<varlistentry>
<term>Versatile</term>
<listitem><para>
The Versatile platform is emulated by QEMU and is therefore a nice way to
test and run &debian; on ARM if you don't have the hardware.
</para></listitem>
</varlistentry>
</variablelist>
</para>
</sect3>
<sect3 arch="arm"><title>Platforms no longer supported by Debian/armel</title>
<variablelist>
<varlistentry>
<term>IOP32x</term>
<listitem><para>
Intel's I/O Processor (IOP) line is found in a number of products
related to data storage and processing, such as the <ulink
url="&url-arm-cyrius-glantank;">GLAN Tank</ulink> from IO-Data and the
<ulink url="&url-arm-cyrius-n2100;">Thecus N2100</ulink>. &debian; has
supported the IOP32x platform in &debian; 7, but does not support
it anymore from version 8 on due to hardware constraints of the platform
which make it unsuitable for the installation of newer &debian; releases.
</para></listitem>
</varlistentry>
</variablelist>
</sect3>
<sect3 arch="arm" id="armhf-armmp-supported-platforms"><title>Platforms supported by Debian/armhf</title>
<para>
The following systems are known to work with &debian;/armhf using the
multiplatform (armmp) kernel:
<variablelist>
<varlistentry>
<term>Freescale MX53 Quick Start Board</term>
<listitem>
<para>
The IMX53QSB is a development board based on the i.MX53 SOC.
</para>
</listitem>
</varlistentry>
<varlistentry>
<term>Versatile Express</term>
<listitem>
<para>
The Versatile Express is a development board series from ARM
consisting of a baseboard which can be equipped with various CPU
daughterboards.
</para>
</listitem>
</varlistentry>
</variablelist>
</para>
<para>
Generally, the ARM multiplatform support in the Linux kernel allows
running &d-i; on armhf systems not explicitly listed above, as long as
the kernel used by &d-i; has support for the target system's components
and a device-tree file for the target is available. In these cases, the
installer can usually provide a working userland installation, but it
probably cannot automatically make the system bootable, as doing that in
many cases requires device-specific information.
</para>
<para>
When using &d-i; on such systems, you have to manually make the system
bootable at the end of the installation, e.g. by running the required
commands in a shell started from within &d-i;.
</para>
</sect3>
<sect3 arch="arm"><title>Platforms no longer supported by Debian/armhf</title>
<variablelist>
<varlistentry>
<term>EfikaMX</term>
<listitem><para>
The EfikaMX platform (Genesi Efika Smartbook and Genesi EfikaMX nettop) has
been supported in &debian; 7 with a platform-specific kernel, but is not
supported anymore from &debian; 8 onwards. The code required to build the
formerly used platform-specific kernel has been removed from the
upstream Linux kernel source in 2012, so Debian cannot provide newer
builds.
</para><para>
Using the armmp multiplatform kernel on the EfikaMX platform would require
device-tree support for it, which is currently not available.
</para></listitem> </varlistentry> </variablelist>
</sect3>
</sect2>
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