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+=======================
+ARM Linux 2.6 and upper
+=======================
+
+    Please check <ftp://ftp.arm.linux.org.uk/pub/armlinux> for
+    updates.
+
+Compilation of kernel
+---------------------
+
+  In order to compile ARM Linux, you will need a compiler capable of
+  generating ARM ELF code with GNU extensions.  GCC 3.3 is known to be
+  a good compiler.  Fortunately, you needn't guess.  The kernel will report
+  an error if your compiler is a recognized offender.
+
+  To build ARM Linux natively, you shouldn't have to alter the ARCH = line
+  in the top level Makefile.  However, if you don't have the ARM Linux ELF
+  tools installed as default, then you should change the CROSS_COMPILE
+  line as detailed below.
+
+  If you wish to cross-compile, then alter the following lines in the top
+  level make file::
+
+    ARCH = <whatever>
+
+  with::
+
+    ARCH = arm
+
+  and::
+
+    CROSS_COMPILE=
+
+  to::
+
+    CROSS_COMPILE=<your-path-to-your-compiler-without-gcc>
+
+  eg.::
+
+    CROSS_COMPILE=arm-linux-
+
+  Do a 'make config', followed by 'make Image' to build the kernel
+  (arch/arm/boot/Image).  A compressed image can be built by doing a
+  'make zImage' instead of 'make Image'.
+
+
+Bug reports etc
+---------------
+
+  Please send patches to the patch system.  For more information, see
+  http://www.arm.linux.org.uk/developer/patches/info.php Always include some
+  explanation as to what the patch does and why it is needed.
+
+  Bug reports should be sent to linux-arm-kernel@lists.arm.linux.org.uk,
+  or submitted through the web form at
+  http://www.arm.linux.org.uk/developer/
+
+  When sending bug reports, please ensure that they contain all relevant
+  information, eg. the kernel messages that were printed before/during
+  the problem, what you were doing, etc.
+
+
+Include files
+-------------
+
+  Several new include directories have been created under include/asm-arm,
+  which are there to reduce the clutter in the top-level directory.  These
+  directories, and their purpose is listed below:
+
+  ============= ==========================================================
+   `arch-*`     machine/platform specific header files
+   `hardware`   driver-internal ARM specific data structures/definitions
+   `mach`       descriptions of generic ARM to specific machine interfaces
+   `proc-*`     processor dependent header files (currently only two
+                categories)
+  ============= ==========================================================
+
+
+Machine/Platform support
+------------------------
+
+  The ARM tree contains support for a lot of different machine types.  To
+  continue supporting these differences, it has become necessary to split
+  machine-specific parts by directory.  For this, the machine category is
+  used to select which directories and files get included (we will use
+  $(MACHINE) to refer to the category)
+
+  To this end, we now have arch/arm/mach-$(MACHINE) directories which are
+  designed to house the non-driver files for a particular machine (eg, PCI,
+  memory management, architecture definitions etc).  For all future
+  machines, there should be a corresponding arch/arm/mach-$(MACHINE)/include/mach
+  directory.
+
+
+Modules
+-------
+
+  Although modularisation is supported (and required for the FP emulator),
+  each module on an ARM2/ARM250/ARM3 machine when is loaded will take
+  memory up to the next 32k boundary due to the size of the pages.
+  Therefore, is modularisation on these machines really worth it?
+
+  However, ARM6 and up machines allow modules to take multiples of 4k, and
+  as such Acorn RiscPCs and other architectures using these processors can
+  make good use of modularisation.
+
+
+ADFS Image files
+----------------
+
+  You can access image files on your ADFS partitions by mounting the ADFS
+  partition, and then using the loopback device driver.  You must have
+  losetup installed.
+
+  Please note that the PCEmulator DOS partitions have a partition table at
+  the start, and as such, you will have to give '-o offset' to losetup.
+
+
+Request to developers
+---------------------
+
+  When writing device drivers which include a separate assembler file, please
+  include it in with the C file, and not the arch/arm/lib directory.  This
+  allows the driver to be compiled as a loadable module without requiring
+  half the code to be compiled into the kernel image.
+
+  In general, try to avoid using assembler unless it is really necessary.  It
+  makes drivers far less easy to port to other hardware.
+
+
+ST506 hard drives
+-----------------
+
+  The ST506 hard drive controllers seem to be working fine (if a little
+  slowly).  At the moment they will only work off the controllers on an
+  A4x0's motherboard, but for it to work off a Podule just requires
+  someone with a podule to add the addresses for the IRQ mask and the
+  HDC base to the source.
+
+  As of 31/3/96 it works with two drives (you should get the ADFS
+  `*configure` harddrive set to 2). I've got an internal 20MB and a great
+  big external 5.25" FH 64MB drive (who could ever want more :-) ).
+
+  I've just got 240K/s off it (a dd with bs=128k); thats about half of what
+  RiscOS gets; but it's a heck of a lot better than the 50K/s I was getting
+  last week :-)
+
+  Known bug: Drive data errors can cause a hang; including cases where
+  the controller has fixed the error using ECC. (Possibly ONLY
+  in that case...hmm).
+
+
+1772 Floppy
+-----------
+  This also seems to work OK, but hasn't been stressed much lately.  It
+  hasn't got any code for disc change detection in there at the moment which
+  could be a bit of a problem!  Suggestions on the correct way to do this
+  are welcome.
+
+
+`CONFIG_MACH_` and `CONFIG_ARCH_`
+---------------------------------
+  A change was made in 2003 to the macro names for new machines.
+  Historically, `CONFIG_ARCH_` was used for the bonafide architecture,
+  e.g. SA1100, as well as implementations of the architecture,
+  e.g. Assabet.  It was decided to change the implementation macros
+  to read `CONFIG_MACH_` for clarity.  Moreover, a retroactive fixup has
+  not been made because it would complicate patching.
+
+  Previous registrations may be found online.
+
+    <http://www.arm.linux.org.uk/developer/machines/>
+
+Kernel entry (head.S)
+---------------------
+  The initial entry into the kernel is via head.S, which uses machine
+  independent code.  The machine is selected by the value of 'r1' on
+  entry, which must be kept unique.
+
+  Due to the large number of machines which the ARM port of Linux provides
+  for, we have a method to manage this which ensures that we don't end up
+  duplicating large amounts of code.
+
+  We group machine (or platform) support code into machine classes.  A
+  class typically based around one or more system on a chip devices, and
+  acts as a natural container around the actual implementations.  These
+  classes are given directories - arch/arm/mach-<class> and
+  arch/arm/mach-<class> - which contain the source files to/include/mach
+  support the machine class.  This directories also contain any machine
+  specific supporting code.
+
+  For example, the SA1100 class is based upon the SA1100 and SA1110 SoC
+  devices, and contains the code to support the way the on-board and off-
+  board devices are used, or the device is setup, and provides that
+  machine specific "personality."
+
+  For platforms that support device tree (DT), the machine selection is
+  controlled at runtime by passing the device tree blob to the kernel.  At
+  compile-time, support for the machine type must be selected.  This allows for
+  a single multiplatform kernel build to be used for several machine types.
+
+  For platforms that do not use device tree, this machine selection is
+  controlled by the machine type ID, which acts both as a run-time and a
+  compile-time code selection method.  You can register a new machine via the
+  web site at:
+
+    <http://www.arm.linux.org.uk/developer/machines/>
+
+  Note: Please do not register a machine type for DT-only platforms.  If your
+  platform is DT-only, you do not need a registered machine type.
+
+---
+
+Russell King (15/03/2004)