mirror of
https://github.com/xen-project/xen.git
synced 2026-10-29 18:50:05 +01:00
Jonathan Davies
02e34c504d
Since libxc is re-entrant, there is no need for the OCaml bindings to
prevent more than one thread from entering libxc concurrently.
Previously, the OCaml bindings had prevented re-entrancy by not using
caml_{enter,leave}_blocking_section in the C stubs. The absence of
these calls meant that the global lock remained held during
hypercalls. This caused multi-threaded applications to completely lock
up during long-running hypercalls.
Calls to these functions were present but commented out in the OCaml
bindings some years ago when libxc was not fully re-entrant.
Instead, we now do call caml_{enter,leave}_blocking_section in all the
places it used to be commented out, meaning that the global lock is
released during those hypercalls. We also no longer assert the
XC_OPENFLAG_NON_REENTRANT flag when calling xc_interface_open because
the caller no longer does re-entrancy prevention at those places.
This patch has now gone through a XenRT nightly test; no problems were
observed.
Signed-off-by: Jonathan Davies <jonathan.davies@citrix.com>
Committed-by: Ian Jackson <ian.jackson@eu.citrix.com>
#################################
__ __ _ _ ____
\ \/ /___ _ __ | || | |___ \
\ // _ \ '_ \ | || |_ __) |
/ \ __/ | | | |__ _| / __/
/_/\_\___|_| |_| |_|(_)_____|
#################################
http://www.xen.org/
What is Xen?
============
Xen is a Virtual Machine Monitor (VMM) originally developed by the
Systems Research Group of the University of Cambridge Computer
Laboratory, as part of the UK-EPSRC funded XenoServers project. Xen
is freely-distributable Open Source software, released under the GNU
GPL. Since its initial public release, Xen has grown a large
development community, spearheaded by xen.org (http://www.xen.org).
The 4.2 release offers excellent performance, hardware support and
enterprise-grade features such as x86_32-PAE, x86_64, SMP guests and
live relocation of VMs. Ports to Linux, NetBSD, FreeBSD and Solaris
are available from the community.
This file contains some quick-start instructions to install Xen on
your system. For full documentation, see the Xen User Manual. If this
is a pre-built release then you can find the manual at:
dist/install/usr/share/doc/xen/pdf/user.pdf
If you have a source release, then 'make -C docs' will build the
manual at docs/pdf/user.pdf.
Quick-Start Guide
=================
First, there are a number of prerequisites for building a Xen source
release. Make sure you have all the following installed, either by
visiting the project webpage or installing a pre-built package
provided by your OS distributor:
* GCC v3.4 or later
* GNU Make
* GNU Binutils
* Development install of zlib (e.g., zlib-dev)
* Development install of Python v2.3 or later (e.g., python-dev)
* Development install of curses (e.g., libncurses-dev)
* Development install of openssl (e.g., openssl-dev)
* Development install of x11 (e.g. xorg-x11-dev)
* Development install of uuid (e.g. uuid-dev)
* Development install of yajl (e.g. libyajl-dev)
* Development install of libaio (e.g. libaio-dev) version 0.3.107 or
greater. Set CONFIG_SYSTEM_LIBAIO in .config if this is not available.
* bridge-utils package (/sbin/brctl)
* iproute package (/sbin/ip)
* hotplug or udev
* GNU bison and GNU flex
* GNU gettext
* 16-bit x86 assembler, loader and compiler (dev86 rpm or bin86 & bcc debs)
* ACPI ASL compiler (iasl)
* markdown
Second, you need to acquire a suitable kernel for use in domain 0. If
possible you should use a kernel provided by your OS distributor. If
no suitable kernel is available from your OS distributor then refer to
http://wiki.xen.org/wiki/XenDom0Kernels for suggestions for
suitable kernels to use.
If you are looking to compile a Dom0 kernel from source, please refer to
http://wiki.xen.org/wiki/XenParavirtOps.
[NB. Unless noted otherwise, all the following steps should be
performed with root privileges.]
1. Download and untar the source tarball file. This will be a
file named xen-unstable-src.tgz, or xen-$version-src.tgz.
You can also pull the current version from the mercurial
repository at http://xenbits.xen.org/
# tar xzf xen-unstable-src.tgz
Assuming you are using the unstable tree, this will
untar into xen-unstable. The rest of the instructions
use the unstable tree as an example, substitute the
version for unstable.
2. cd to xen-unstable (or whatever you sensibly rename it to).
3. For the very first build, or if you want to destroy build trees,
perform the following steps:
# make world
# make install
This will create and install onto the local machine. It will build
the xen binary (xen.gz), the tools and the documentation.
You can override the destination for make install by setting DESTDIR
to some value.
4. To rebuild an existing tree without modifying the config:
# make dist
This will build and install xen, tools, and docs into the local dist/
directory.
You can override the destination for make install by setting DISTDIR
to some value.
make install and make dist differ in that make install does the
right things for your local machine (installing the appropriate
version of hotplug or udev scripts, for example), but make dist
includes all versions of those scripts, so that you can copy the dist
directory to another machine and install from that distribution.
Python Runtime Libraries
========================
Xend (the Xen daemon) has the following runtime dependencies:
* Python 2.3 or later.
In some distros, the XML-aspects to the standard library
(xml.dom.minidom etc) are broken out into a separate python-xml package.
This is also required.
In more recent versions of Debian and Ubuntu the XML-aspects are included
in the base python package however (python-xml has been removed
from Debian in squeeze and from Ubuntu in intrepid).
URL: http://www.python.org/
Debian: python
* For optional SSL support, pyOpenSSL:
URL: http://pyopenssl.sourceforge.net/
Debian: python-pyopenssl
* For optional PAM support, PyPAM:
URL: http://www.pangalactic.org/PyPAM/
Debian: python-pam
* For optional XenAPI support in XM, PyXML:
URL: http://codespeak.net/lxml/
Debian: python-lxml
YUM: python-lxml
Intel(R) Trusted Execution Technology Support
=============================================
Intel's technology for safer computing, Intel(R) Trusted Execution Technology
(Intel(R) TXT), defines platform-level enhancements that provide the building
blocks for creating trusted platforms. For more information, see
http://www.intel.com/technology/security/.
Intel(R) TXT support is provided by the Trusted Boot (tboot) module in
conjunction with minimal logic in the Xen hypervisor.
Tboot is an open source, pre- kernel/VMM module that uses Intel(R) TXT to
perform a measured and verified launch of an OS kernel/VMM.
The Trusted Boot module is available from
http://sourceforge.net/projects/tboot. This project hosts the code in a
mercurial repo at http://tboot.sourceforge.net/hg/tboot.hg and contains
tarballs of the source. Instructions in the tboot README describe how
to modify grub.conf to use tboot to launch Xen.
There are optional targets as part of Xen's top-level makefile that will
download and build tboot: install-tboot, build-tboot, dist-tboot, clean-tboot.
These will download the latest tar file from the SourceForge site using wget,
then build/install/dist according to Xen's settings.