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Release notes
=============
1. Preface
a. Proprietary notice
Copyright (c) 2011, ARM Limited
All rights reserved.
THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND
CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED
WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER
OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL,
SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT
LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF
USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED
AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF
THE POSSIBILITY OF SUCH DAMAGE.
b. License details
Copyright (c) 2009-11, ARM Limited. All rights reserved.
Redistribution and use in source and binary forms, with
or without modification, are permitted provided that the
following conditions are met:
* Redistributions of source code must retain the above
copyright notice,
this list of conditions and the following disclaimer.
* Redistributions in binary form must reproduce the
above copyright notice,
this list of conditions and the following disclaimer
in the documentation and/or other materials provided
with the distribution.
* Neither the name of ARM nor the names of its
contributors may be used to endorse or promote products
derived from this software without specific prior written
permission.
c. Document confidentiality status
Redistribution of source and compiled code is subject to the
license terms above.
d. Product status
ARM Virtualizer for Cortex-A15/Cortex-A7 Task Migration v2.1
e. Web address
Not applicable.
f. Feedback on the ARM Virtualizer software
None at present.
g. Feedback on this release note document
None at present.
2. Release details
a. Product release status
v2.1
b. ARM Virtualizer software release v2.1
This software release is a v2.1 snapshot of the ARM
Virtualizer software.
The ARM Virtualizer software is example code that demonstrates
cluster context switching capability on a coherent dual
cluster system composed of a Cortex-A7 cluster and a
Cortex-A15 cluster.
The intent behind this delivery is to allow
inspection of the software architecture and to
demonstrate existing functionality.
It is possible to execute the ARM Virtualizer software on a
Kingfisher Real-Time System Model (RTSM VE Cortex-A15 KF CCI
version 6.2 Beta).
This model may be obtained from ARM by separate arrangement.
c. Deliverables
This release contains:
- Source code for a basic boot wrapper.
This boot wrapper performs minimal system initialization
and boots the system with the Virtualizer code. It also
permits booting the system with an optional Linux kernel
image and an accompanying root filesystem [both NOT
supplied with this release].
- Source code for the ARM Virtualizer software.
- Pertinent documentation covering the release components,
their installation and usage.
d. Functionality included
This release of the ARM Virtualizer software is capable of rapid
and robust cluster context switching on a coherent system
between a cluster of up to four Cortex-A7 processors and a
cluster of up to four Cortex-A15 processors.
In addition, this release of the ARM Virtualizer software
permits payload software (bare-metal software or a Linux
operating system kernel) built for the Cortex-A15 processor
cluster to run un-modified on a Cortex-A7 processor cluster.
This release does not support execution of software built for the
Cortex-A7 cluster on the Cortex-A15 cluster.
e. New features
1. Code optimizations have been done to lower the number of cycles
taken to switch payload software execution between the two clusters.
An internal cycle accurate emulation platform was used to perform
the optimizations. It is not possible to undertake the same activity
on the ARM FastModels. The changes mostly center around:
a. Replacement & rework of C code by assembler routines for
initialising the Secure Monitor and HYP mode environment after a
warm reset.
b. Context of the vGIC shared distributor interface is not saved any
longer. Since the interface maintains its state across a switch,
changes are made to it directly while restoring context on the
inbound cluster.
c. MMU is enabled as soon as possible after a warm reset to minimize
strongly ordered accesses.
d. Barrier instructions are being used more optimally.
e. The copy_words() routine which was used to save and restore the vGIC
context using word sized loads and stores has been replaced by the
memcpy() library routine. Depending upon the number of bytes that
need to be transferred, it chooses an optimal way of saving and
restoring context.
2. The variant field of the KFS_ID register is used to distinguish
between the FastModels and other platform types.
f. Known issues
1. This release does not support execution of software
built for the Cortex-A7 cluster on the Cortex-A15
cluster.
2. This release is intended to be built in a Linux development
environment. Environments other than Linux are not supported.
3. The snoop hit rate calculation support depends on per-CPU tube
constructs. These are currently only present in internal development
versions of the ARM FastModels. A forthcoming release of the ARM
FastModels will incorporate this functionality. For the moment,
attempts to write to non-existent tubes will be treated as a no-op.
(See docs/04-Cache-hit-rate-howto.txt for details).
4. This release provides instructions to build and run
large filesystems with the Virtualizer. The use of
large filesystems with the current FastModels
release (RTSM VE Cortex-A15 KF CCI version
6.2 Beta) is known to be unstable.
g. Issues resolved since last release
1. Bug fixes
1. vGIC HYP view interface handling code in (common/vgiclib.c) now
detects the number of implemented list registers from the vgic
type register instead of assuming that the maximum (64) will be
present.
h. Test cases and results
1. This release has been tested for correct cluster switching
operation at ~12 million cycle switching intervals with
bare-metal and Linux kernel payloads.
2. This release has been tested using a select subset of an ARM
internal Linux based stress testing suite.
i. Other information
Not applicable.
3. Documentation
The docs subdirectory contains the following notes:
01-Usage.txt: General installation and usage instructions.
02-Code-layout.txt: Overview of the code layout.
03-Linux-kernel-build.txt: Instructions on obtaining and
building a Linux kernel image suitable for the virtualizer.
04-Cache-hit-rate-howto.txt: Description of the MTI trace
plugin infrastructure and ways to use the trace for
estimating snoop hit rates across cluster switches.
05-FAQ.txt: Placeholder for commonly asked questions with
answers.
06-Optional-rootfs-build.txt: Instructions for building and
using rootfilesystems with the virtualizer.
4. Tools
a. Tools
1. ARM RealView Development Suite version 4.1 [Build 514].
2. Kingfisher Real-Time System Model (RTSM VE Cortex-A15 KF CCI
version 6.2 Beta).
b. Operating systems
1. Ubuntu 10.10.
2. Red Hat Enterprise Linux WS release 4 (Nahant Update 4).
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