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Ian Campbell
1a3e84bd85
These are provided using the "script=" syntax described in docs/misc/xl-disk-configuration.txt. The existing hotplug scripts currently conflate two different concepts, namely that of making a datapath available in the backend domain (logging into iSCSI LUNs and the like) and that of actually connecting that datapath to a Xen backend path (e.g. writing "physical-device" node in xenstore to bring up blkback). For this reason the script support implemented here is only supported in conjunction with backendtype=phy. Eventually we hope to rework the hotplug scripts to separate the to concepts, but that is not 4.2 material. In addition there are some other subtleties: - Previously in the blktap case we would add "script = .../blktap" to the backend flex array, but then jumped to the PHY case which added "script = .../block" too. The block one takes precendence since it comes second. This was, accidentally, correct. The blktap script is for blktap1 devices and not blktap2 devices. libxl completely manages the blktap2 side of things without resorting to hotplug scripts and creates a blkback device directly. Therefore the "block" script is always the correct one to call. Custom script are not supported in this context. - libxl should not write the "physical-device" node. This is the responsibility of the block script. Writing the "physical-device" node in libxl basically completely short-cuts the standard block hotplug script which uses "physical-device" to know if it has run already or not. In the case of more complex scripts libxl cannot know the right value to write here anyway, in particular the device may not exist until after the script is called. This change has the side effect of re-enabling the checks for device sharing aspect of the default block script, which I have tested and which now cause libxl to properly abort now that libxl properly checks for hotplug script errors. There is no sharing check for blktap2 since even if you reuse the same vhd the resulting tap device is different. I would have preferred to simply write the "physical-device" node for the blktap2 case but the hotplug script infrastructure is not currently setup to handle LIBXL__DEVICE_KIND_VBD devices without a hotplug script (backendtype phy and tap both end up as KIND_VBD). Changing this was more surgery than I was happy doing for 4.2 and therefore I have simply hardcoded to the block script for the LIBXL_DISK_BACKEND_TAP case. - libxl__device_disk_set_backend running against a phy device with a script cannot stat the device to check its properties since it may not exist until the script is run. Therefore I have special cased this in disk_try_backend to simply assume that backend == phy is always ok if a script was configured. Similarly the other backend types are always rejected if a script was configured. Note that the reason for implementing the default script behaviour in device_disk_add instead of libxl__device_disk_setdefault is because we need to be able to tell when the script was user-supplied rather than defaulted by libxl in order to correctly implement the above. The setdefault function must be idempotent so we cannot simply update disk->script. I suspect that for 4.3 a script member should be added to libxl__device, this would also help in the case above of handling devices with no script in a consistent manner. This is not 4.2 material. - When the block script falls through and shells out to a block-$type script it used to pass "$node" however the only place this was assigned was in the remove+phy case (in which case it contains the file:// derived /dev/loopN device), and in that case the script exits without falling through to the block-$type case. Since libxl never creates a type other than phy this never happens in practice anyway and we now call the correct block-$type script directly. But fix it up anyway since it is confusing. - The block-nbd and block-enbd scripts which we supply appear to be broken WRT the hotplug calling convention, in that they seem to expect a command line parameter (perhaps the $node described above) rather than reading the appropriate node from xenstore. I rather suspect this was broken by 7774:e2e7f47e6f79 in November 2005. I think it is safe to say no one is using these scripts! I haven't fixed this here. It would be good to track down some working scripts and either incorproate them or defer to them in their existing home (e.g. if they live somewhere useful like the nbd tools package). - Added a few block script related entries to check-xl-disk-parse from http://backdrift.org/xen-block-iscsi-script-with-multipath-support and http://lists.linbit.com/pipermail/drbd-user/2008-September/010221.html / http://www.drbd.org/users-guide-emb/s-xen-configure-domu.html (and snuck in another interesting empty CDROM case) This highlighted two bugs in the libxlu disk parser handling of the deprecated "<script>:" prefix: - It was failing to prefix with "block-" to construct the actual script name - The regex for matching iscsi or drdb or e?nbd was incorrect - Use libxl__abs_path for the nic script too. Just because the existing code nearly tricked me into repeating the mistake I have tested with a custom block script which uses "lvchange -a" to dynamically add remove the referenced device (simulates iSCSI login/logout without requiring me to faff around setting up an iSCSI target). I also tested on a blktap2 system. I haven't directly tested anything more complex like iscsi: or nbd: other than what check-xl-disk-parse exercises. [ reran flex/bison -iwj ] Signed-off-by: Ian Campbell <ian.campbell@citrix.com> Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
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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.
* Development install of GLib v2.0 (e.g. libglib2.0-dev)
* pkg-config
* 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
In addition to the above there are a number of optional build
prerequisites. Omitting these will cause the related features to be
disabled at compile time:
* Development install of Ocaml (e.g. ocaml-nox and
ocaml-findlib). Required to build ocaml components which
includes the alternative ocaml xenstored.
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:
# ./configure
# make world
# make install
If you want, you can run ./configure --help to see the list of
options available options when building and installing Xen.
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.