Update and extend the "Supported Hardware" section for

armel and armhf.

1 files changed, 87 insertions, 8 deletions

diff --git a/en/hardware/supported/arm.xml b/en/hardware/supported/arm.xml
index c899eec2d..f56a1ae57 100644
--- a/en/hardware/supported/arm.xml
+++ b/en/hardware/supported/arm.xml
@@ -6,24 +6,80 @@
 
 <para>
 
-Each distinct ARM architecture requires its own kernel. Because of
-this the standard &debian; distribution only supports installation on
-a number of the most common platforms. The &debian; userland however may be
-used by <emphasis>any</emphasis> ARM CPU.
+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 "systems-on-chip" (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>
 
-Most ARM CPUs may be run in either endian mode (big or little). However,
-the majority of current system implementation uses little-endian mode.
-&debian; currently only supports little-endian ARM systems.
+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 "one-fits-all" 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.
 
-The supported platforms are:
+</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>
 
@@ -86,4 +142,27 @@ test and run &debian; on ARM if you don't have the hardware.
 </variablelist>
 
 </para>
+</sect3>
+
+<sect3 arch="arm"><title>Platforms supported by Debian/armhf</title>
+
+  <para>
+  The following platforms are supported by &debian;/armhf using the
+  multiplatform (armmp) kernel:
+
+  <variablelist>
+
+      <varlistentry>
+        <term>Freescale MX53 Quick Start Board, Codename "LOCO"</term>
+        <listitem>
+          <para>   
+            The IMX53QSB is a development board based on the i.MX53 SOC.
+          </para>
+        </listitem>
+      </varlistentry>
+
+    </variablelist>
+  </para>
+</sect3>
+
   </sect2>