When booting without device tree, the Linux kernels uses the $R1
register to determine the machine type. The list of values is
registered at [1].
There are two entries for the Raspberry Pi:
- https://www.arm.linux.org.uk/developer/machines/list.php?mid=3138
name: MACH_TYPE_BCM2708
value: 0xc42 (3138)
status: Active, not mainlined
date: 15 Oct 2010
- https://www.arm.linux.org.uk/developer/machines/list.php?mid=4828
name: MACH_TYPE_BCM2835
value: 4828
status: Active, mainlined
date: 6 Dec 2013
QEMU always used the non-mainlined type MACH_TYPE_BCM2708.
The value 0xc43 is registered to 'MX51_GGC' (processor i.MX51), and
0xc44 to 'Western Digital Sharespace NAS' (processor Marvell 88F5182).
The Raspberry Pi foundation bootloader only sets the BCM2708 machine
type, see [2] or [3]:
133 9:
134 mov r0, #0
135 ldr r1, =3138 @ BCM2708 machine id
136 ldr r2, atags @ ATAGS
137 bx r4
U-Boot only uses MACH_TYPE_BCM2708 (see [4]):
25 /*
26 * 2835 is a SKU in a series for which the 2708 is the first or primary SoC,
27 * so 2708 has historically been used rather than a dedicated 2835 ID.
28 *
29 * We don't define a machine type for bcm2709/bcm2836 since the RPi Foundation
30 * chose to use someone else's previously registered machine ID (3139, MX51_GGC)
31 * rather than obtaining a valid ID:-/
32 *
33 * For the bcm2837, hopefully a machine type is not needed, since everything
34 * is DT.
35 */
While the definition MACH_BCM2709 with value 0xc43 was introduced in
a commit described "Add 2709 platform for Raspberry Pi 2" out of the
mainline Linux kernel, it does not seem used, and the platform is
introduced with Device Tree support anyway (see [5] and [6]).
Remove the unused values (0xc43 introduced in commit 1df7d1f930
"raspi: add raspberry pi 2 machine" and 0xc44 in commit bade58166f
"raspi: Raspberry Pi 3 support"), keeping only MACH_TYPE_BCM2708.
[1] https://www.arm.linux.org.uk/developer/machines/
[2] https://github.com/raspberrypi/tools/blob/920c7ed2e/armstubs/armstub7.S#L135
[3] https://github.com/raspberrypi/tools/blob/49719d554/armstubs/armstub7.S#L64
[4] https://gitlab.denx.de/u-boot/u-boot/blob/v2015.04/include/configs/rpi-common.h#L18
[5] https://github.com/raspberrypi/linux/commit/d9fac63adac#diff-6722037d79570df5b392a49e0e006573R526
[6] http://lists.infradead.org/pipermail/linux-rpi-kernel/2015-February/001268.html
Cc: Zoltán Baldaszti <bztemail@gmail.com>
Cc: Pekka Enberg <penberg@iki.fi>
Cc: Stephen Warren <swarren@nvidia.com>
Cc: Kshitij Soni <kshitij.soni@broadcom.com>
Cc: Michael Chan <michael.chan@broadcom.com>
Cc: Andrew Baumann <Andrew.Baumann@microsoft.com>
Reviewed-by: Alistair Francis <alistair.francis@wdc.com>
Signed-off-by: Philippe Mathieu-Daudé <f4bug@amsat.org>
Reviewed-by: Niek Linnenbank <nieklinnenbank@gmail.com>
Message-id: 20200208165645.15657-2-f4bug@amsat.org
Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
===========
QEMU README
===========
QEMU is a generic and open source machine & userspace emulator and
virtualizer.
QEMU is capable of emulating a complete machine in software without any
need for hardware virtualization support. By using dynamic translation,
it achieves very good performance. QEMU can also integrate with the Xen
and KVM hypervisors to provide emulated hardware while allowing the
hypervisor to manage the CPU. With hypervisor support, QEMU can achieve
near native performance for CPUs. When QEMU emulates CPUs directly it is
capable of running operating systems made for one machine (e.g. an ARMv7
board) on a different machine (e.g. an x86_64 PC board).
QEMU is also capable of providing userspace API virtualization for Linux
and BSD kernel interfaces. This allows binaries compiled against one
architecture ABI (e.g. the Linux PPC64 ABI) to be run on a host using a
different architecture ABI (e.g. the Linux x86_64 ABI). This does not
involve any hardware emulation, simply CPU and syscall emulation.
QEMU aims to fit into a variety of use cases. It can be invoked directly
by users wishing to have full control over its behaviour and settings.
It also aims to facilitate integration into higher level management
layers, by providing a stable command line interface and monitor API.
It is commonly invoked indirectly via the libvirt library when using
open source applications such as oVirt, OpenStack and virt-manager.
QEMU as a whole is released under the GNU General Public License,
version 2. For full licensing details, consult the LICENSE file.
Building
========
QEMU is multi-platform software intended to be buildable on all modern
Linux platforms, OS-X, Win32 (via the Mingw64 toolchain) and a variety
of other UNIX targets. The simple steps to build QEMU are:
.. code-block:: shell
mkdir build
cd build
../configure
make
Additional information can also be found online via the QEMU website:
* `<https://qemu.org/Hosts/Linux>`_
* `<https://qemu.org/Hosts/Mac>`_
* `<https://qemu.org/Hosts/W32>`_
Submitting patches
==================
The QEMU source code is maintained under the GIT version control system.
.. code-block:: shell
git clone https://git.qemu.org/git/qemu.git
When submitting patches, one common approach is to use 'git
format-patch' and/or 'git send-email' to format & send the mail to the
qemu-devel@nongnu.org mailing list. All patches submitted must contain
a 'Signed-off-by' line from the author. Patches should follow the
guidelines set out in the CODING_STYLE.rst file.
Additional information on submitting patches can be found online via
the QEMU website
* `<https://qemu.org/Contribute/SubmitAPatch>`_
* `<https://qemu.org/Contribute/TrivialPatches>`_
The QEMU website is also maintained under source control.
.. code-block:: shell
git clone https://git.qemu.org/git/qemu-web.git
* `<https://www.qemu.org/2017/02/04/the-new-qemu-website-is-up/>`_
A 'git-publish' utility was created to make above process less
cumbersome, and is highly recommended for making regular contributions,
or even just for sending consecutive patch series revisions. It also
requires a working 'git send-email' setup, and by default doesn't
automate everything, so you may want to go through the above steps
manually for once.
For installation instructions, please go to
* `<https://github.com/stefanha/git-publish>`_
The workflow with 'git-publish' is:
.. code-block:: shell
$ git checkout master -b my-feature
$ # work on new commits, add your 'Signed-off-by' lines to each
$ git publish
Your patch series will be sent and tagged as my-feature-v1 if you need to refer
back to it in the future.
Sending v2:
.. code-block:: shell
$ git checkout my-feature # same topic branch
$ # making changes to the commits (using 'git rebase', for example)
$ git publish
Your patch series will be sent with 'v2' tag in the subject and the git tip
will be tagged as my-feature-v2.
Bug reporting
=============
The QEMU project uses Launchpad as its primary upstream bug tracker. Bugs
found when running code built from QEMU git or upstream released sources
should be reported via:
* `<https://bugs.launchpad.net/qemu/>`_
If using QEMU via an operating system vendor pre-built binary package, it
is preferable to report bugs to the vendor's own bug tracker first. If
the bug is also known to affect latest upstream code, it can also be
reported via launchpad.
For additional information on bug reporting consult:
* `<https://qemu.org/Contribute/ReportABug>`_
Contact
=======
The QEMU community can be contacted in a number of ways, with the two
main methods being email and IRC
* `<mailto:qemu-devel@nongnu.org>`_
* `<https://lists.nongnu.org/mailman/listinfo/qemu-devel>`_
* #qemu on irc.oftc.net
Information on additional methods of contacting the community can be
found online via the QEMU website:
* `<https://qemu.org/Contribute/StartHere>`_