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Andrew Cooper
c55ad3aa85
Currently, the buffers for crash notes are allocated per CPU when a
KEXEC_CMD_kexec_get_range hypercall is made, referencing the CPU in
question. This has certain problems including not being able to
allocate the crash buffers if the host is out of memory when crashing.
In addition, my forthcoming code to support 32bit kdump kernels on
64bit Xen on large (>64GB) boxes will require some guarentees as to
where the crash note buffers are actually allocated in physical
memory. This is far easier to sort out at boot time, rather than
after dom0 has been booted and potentially using the physical memory
required.
Therefore, allocate the crash note buffers at boot time.
Changes since v6:
* Tweak kexec_init() to use xzmalloc_array(), and to defer
registering the
crashdump keyhandler until the crash notes have been successfully
allocated.
Changes since v5:
* Introduce sizeof_cpu_notes to move calculation of note size into a
separate location.
* Tweak sizeof_note() to return size_t rather than int, as it is a
function based upon sizeof().
Changes since v4:
* Replace the current cpu crash note scheme of using void pointers
and hand calculating the size each time is needed, by a range
structure containing a pointer and a size. This removes duplicate
times where the size is calculated.
* Tweak kexec_get_cpu(). Don't fail if a cpu is offline because it
may already have crash notes, and may be up by the time a crash
happens. Split the error conditions up to return ERANGE for an
out-of-range cpu request rather than EINVAL. Finally, returning a
range of zeros is acceptable, so do this in preference to failing.
Changes since v3:
* Alter the spinlocks to avoid calling xmalloc/xfree while holding
the lock.
* Tidy up the coding style used.
Changes since v2:
* Allocate crash_notes dynamically using nr_cpu_ids at boot time,
rather than statically using NR_CPUS.
* Fix the incorrect use of signed integers for cpu id.
* Fix collateral damage to do_crashdump_trigger() and
crashdump_trigger_handler caused by reordering sizeof_note() and
setup_note()
* Tweak the issue about returing -ENOMEM from kexec_init_cpu_note().
No functional change.
* Change kexec_get_cpu() to attempt to allocate crash note buffers
in case we have more free memory now than when the pcpu came up.
* Now that there are two codepaths possibly allocating crash notes,
protect the allocation itself with a spinlock.
Changes since v1:
* Use cpu hotplug notifiers to handle allocating of the notes
buffers rather than assuming the boot state of cpus will be the
same as the crash state.
* Move crash_notes from being per_cpu. This is because the kdump
kernel elf binary put in the crash area is hard coded to physical
addresses which the dom0 kernel typically obtains at boot time.
If a cpu is offlined, its buffer should not be deallocated because
the kdump kernel would read junk when trying to get the crash
notes. Similarly, the same problem would occur if the cpu was
re-onlined later and its crash notes buffer was allocated
elsewhere.
* Only attempt to allocate buffers if a crash area has been
specified. Else, allocating crash note buffers is a waste of
space. Along with this, change the test in kexec_get_cpu to
return -EINVAL if no buffers have been allocated.
Signed-off-by: Andrew Cooper <andrew.cooper3@citrix.com>
Committed-by: Keir Fraser <keir@xen.org>
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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
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.