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From: Ian P. <m+I...@cl...> - 2005-08-04 01:00:51
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Although everyone is working flat out to get Xen 3.0 ready, we thought it was about time we released a Xen 2.0.7 update as there have been a bunch of fixes queued up in the testing tree for a while. For example: * 'noirqbalance' parameter to workaround buggy ES7000 chipsets=20 * vm relocation tools fixes * fix fp bug that was triggered by certain user kernel configs * fix for the console warning when udp_poll() receives fragmented skbuffs Upgrading is probably not critical for most people, but is advisable. Best, Ian |
From: Ian P. <m+I...@cl...> - 2005-03-16 13:13:13
|
Folks, I've talked about it a number of times, but now we're actually going to do it: we want to move the mailing lists off sourceforge and onto one of our own servers, so hopefully we can get messages delivered with reasonable delay and in-order. The reordering problems that sourceforge was suffering last week have been the final straw. As well as moving the list server we'd like to create a new list "xen-users", thus we'd have 4 lists in total: xen-devel : for discussion about Xen development, and real bug reports xen-users : for questions about configuring and running Xen xen-announce : a low volume list to announce new releases=20 xen-changelog : automated list that posts notifications of checkins The new list server is now open for subscriptions, but won't be sending out email until the 'flag day' on Mon 28 March, when we'll close down the old list so it bounces anything that's posted to it.=20 I'm sorry there's no transparent way of moving everyone over, but without knowing everyone's subscription password that's not possible. The new list server subscription page is at http://lists.xensource.com/ There's also a searchable archive of xen-devel available at the same location, and also a link to a Xen source code browser http://lxr.xensource.com. There'll be a wiki and bug tracker going live in a few days too, once we've had a chance to preload some content. As you'd expect, all these services are running in their own VMs on Xen :-) Thanks go to James Bulpin for setting up and running all the new project infrastructure.=20 Best, Ian |
From: Ian P. <Ian...@cl...> - 2005-03-10 20:47:37
|
Folks, The Xen team are pleased to announce the release of Xen 2.0.5 ! This has a number of important fixes over 2.0.4, so we'd definitely recommend upgrading. Notable changes include: * AGP support now enabled by default * nasty save/restore/migrate problem in xend fixed * memory ballooning with config highmem4g kernels now fixed * nasty floating point issue fixed Tomorrow we'll roll a new version of the graphical demo CD, and also check in a Linux 2.6.11 port to the xen-2.0-testing.bk and xen-unstable.bk trees. Best, Ian |
From: Ian P. <Ian...@cl...> - 2004-11-05 13:26:25
|
The Xen team are pleased to announce the release of Xen 2.0, the open-source Virtual Machine Monitor. Xen enables you to run multiple operating systems images concurrently on the same hardware, securely partitioning the resources of the machine between them. Xen uses a technique called 'para-virtualization' to achieve very low performance overhead -- typically just a few percent relative to native. This new release provides kernel support for Linux 2.4.27/2.6.9 and NetBSD, with FreeBSD and Plan9 to follow in the next few weeks. Xen 2.0 runs on almost the entire set of modern x86 hardware supported by Linux, and is easy to 'drop-in' to an existing Linux installation. The new release has a lot more flexibility in how guest OS virtual I/O devices are configured. For example, you can configure arbitrary firewalling, bridging and routing of guest virtual network interfaces, and use copy-on-write LVM volumes or loopback files for storing guest OS disk images. Another new feature is 'live migration', which allows running OS images to be moved between nodes in a cluster without having to stop them. Visit the Xen homepage for downloads and documentation. http://xen.sf.net |
From: Inaba <B88...@st...> - 2004-02-11 14:19:07
|
Hi All, Recently, I have traced part of the Xen VMM code. but I have some troubles... I could not find out the function ioctl() which is called by the = function do_privcmd() (xeno-1.2.bk/tools/xc/lib/xc_private.h) Is the interface between guest OS and VMM just like the interface = between OS and Hardware ? and another question. Is there any protection in Xen VMM to protect that only Domain 0 could = use the control tools? Inaba |
From: Ian P. <Ian...@cl...> - 2003-09-22 09:42:58
|
Hi, Your receiving this email because I believe you might be interested in hearing about the release of "Xen", a Virtual Machine Monitor (VMM) for x86 that provides high levels of performance and resource isolation. We are in the final stages of preparing a public release of the source code, and have our first 'release candidate' ready. To make it easy for people to experiment with Xen, we've made a demo CD that packages Xen / XenoLinux on to a 'live ISO' RedHat 9 installation. You can boot directly off CD, then start multiple virtual machines, and run Apache, PostgreSQL, Mozilla, ethereal, etc -- pretty much anything. The CD also contains a source snapshot, along with all the build tools. The CD can also be used as an installation disk. You can download the CD iso image from: http://www.cl.cam.ac.uk/netos/xen/downloads/xendemo-1.0rc1.iso We're planning on releasing the final 1.0 version next week, having shaken out any issues that may arise in this release candidate. We're keen to keep this '1.0rc1' version just among 'friends and family', so would appreciate it if you could avoid distributing it too widely, posting to Slashdot etc ;-) To find out more about Xen, the SOSP paper is a good reference: http://www.cl.cam.ac.uk/netos/papers/2003-xensosp.pdf To join the Xen developer's mailing list and ask questions etc visit: http://lists.sourceforge.net/lists/listinfo/xen-devel The project web site should be properly up and running in a week or so, and will be at: http://www.cl.cam.ac.uk/netos/xen I enclose a couple of README files from the CD, and hope that you'll download Xen, have a play, and let us know what you think! Best, Ian README.XEN: ############################# __ __ _ ___ \ \/ /___ _ __ / | / _ \ \ // _ \ '_ \ | || | | | / \ __/ | | | | || |_| | /_/\_\___|_| |_| |_(_)___/ ############################# University of Cambridge Computer Laboratory 31 Aug 2003 http://www.cl.cam.ac.uk/netos/xen About the Xen Virtual Machine Monitor ===================================== "Xen" is a Virtual Machine Monitor (VMM) developed by the Systems Research Group of the University of Cambridge Computer Laboratory, as part of the UK-EPSRC funded XenoServers project. The XenoServers project aims to provide a "public infrastructure for global distributed computing", and Xen plays a key part in that, allowing us to efficiently partition a single machine to enable multiple independent clients to run their operating systems and applications in an environment providing protection, resource isolation and accounting. The project web page contains further information along with pointers to papers and technical reports: http://www.cl.cam.ac.uk/xeno Xen has since grown into a project in its own right, enabling us to investigate interesting research issues regarding the best techniques for virtualizing resources such as the CPU, memory, disk and network. The project has been bolstered by support from Intel Research Cambridge, who are now working closely with us. We're also in receipt of support from Microsoft Research Cambridge to port Windows XP to run on Xen. Xen enables multiple operating system images to execute concurrently on the same hardware with very low performance overhead --- much lower than commercial offerings for the same x86 platform. This is achieved by requiring OSs to be specifically ported to run on Xen, rather than allowing unmodified OS images to be used. Crucially, only the OS needs to be changed -- all of the user-level application binaries, libraries etc can run unmodified. Hence the modified OS kernel can typically just be dropped into any existing OS distribution or installation. Xen currently runs on the x86 architecture, but could in principle be ported to others. In fact, it would have been rather easier to write Xen for pretty much any other architecture as x86 is particularly tricky to handle. A good description of Xen's design, implementation and performance is contained in our October 2003 SOSP paper, available at http://www.cl.cam.ac.uk/netos/papers/2003-xensosp.pdf We have been working on porting 3 different operating systems to run on Xen: Linux 2.4, Windows XP, and NetBSD. The Linux 2.4 port (currently Linux 2.4.22) works very well -- we regularly use it to host complex applications such as PostgreSQL, Apache, BK servers etc. It runs every user-space applications we've tried. We refer to our version of Linux ported to run on Xen as "XenoLinux", although really it's just standard Linux ported to a new virtual CPU architecture that we call xeno-x86 (abbreviated to just "xeno"). Unfortunately, the NetBSD port has stalled due to lack of man power. We believe most of the hard stuff has already been done, and are hoping to get the ball rolling again soon. In hindsight, a FreeBSD 4.8 port might have been more useful to the community. Any volunteers? :-) The Windows XP port is nearly finished. It's running user space applications and is generally in pretty good shape thanks to some hard work by the team over the summer. Of course, there are issues with releasing this code to others. We should be able to release the source and binaries to anyone that has signed the Microsoft academic source license, which these days has very reasonable terms. We are in discussions with Microsoft about the possibility of being able to make binary releases to a larger user community. Obviously, there are issues with product activation in this environment which need to be thought through. So, for the moment, you only get to run multiple copies of Linux on Xen, but we hope this will change before too long. Even running multiple copies of the same OS can be very useful, as it provides a means of containing faults to one OS image, and also for providing performance isolation between the various OS, enabling you to either restrict, or reserve resources for, particular VM instances. It's also useful for development -- each version of Linux can have different patches applied, enabling different kernels to be tried out. For example, the "vservers" patch used by PlanetLab applies cleanly to our ported version of Linux. We've successfully booted over 128 copies of Linux on the same machine (a dual CPU hyperthreaded Xeon box) but we imagine that it would be more normal to use some smaller number, perhaps 10-20. Hardware support ================ Xen is intended to be run on server-class machines, and the current list of supported hardware very much reflects this, avoiding the need for us to write drivers for "legacy" hardware. It is likely that some desktop chipsets will fail to work properly with the default Xen configuration: specifying 'noacpi' or 'ignorebiostables' when booting Xen may help in these cases. Xen requires a "P6" or newer processor (e.g. Pentium Pro, Celeron, Pentium II, Pentium III, Pentium IV, Xeon, AMD Athlon, AMD Duron). Multiprocessor machines are supported, and we also have basic support for HyperThreading (SMT), although this remains a topic for ongoing research. We're also looking at an AMD x86_64 port (though it should run on Opterons in 32-bit mode just fine). Xen can currently use up to 4GB of memory. It's possible for x86 machines to address more than that (64GB), but it requires using a different page table format (3-level rather than 2-level) that we currently don't support. Adding 3-level PAE support wouldn't be difficult, but we'd also need to add support to all the guest OSs. Volunteers welcome! We currently support a relatively modern set of network cards: Intel e1000, Broadcom BCM 57xx (tg3), 3COM 3c905 (3c59x). Adding support for other NICs that support hardware DMA scatter/gather from half-word aligned addresses is relatively straightforward, by porting the equivalent Linux driver. Drivers for a number of other older cards have recently been added [pcnet32, e100, tulip], but are untested and not recommended. Building Xen and XenoLinux ========================== Take a look at the tools/misc/xen-clone script in the BK repository, which will 'bk clone' the live master tree, and then set about building everything. The build procedure for xenolinux is slightly complicated as its done by running the 'mkbuildtree' script over a pristine Linux tree to turn it into a xenolinux tree by adding the 'xeno' architecture. The public master BK repository lives at: bk://xen.bkbits.net/xeno.bk Ian Pratt 9 Sep 2003 README.CD: ############################# __ __ _ ___ \ \/ /___ _ __ / | / _ \ \ // _ \ '_ \ | || | | | / \ __/ | | | | || |_| | /_/\_\___|_| |_| |_(_)___/ ############################# XenDemoCD 1.0 rc1 University of Cambridge Computer Laboratory 18 Sep 2003 http://www.cl.cam.ac.uk/netos/xen Welcome to the Xen Demo CD! Executive Summary ================= This CD is a standalone demo of the Xen Virtual Machine Monitor (VMM) and Linux-2.4 OS port (XenoLinux). It runs entirely off the CD, without requiring hard disk installation. This is achieved using a RAM disk to store mutable file system data while using the CD for everything else. The CD can also be used for installing Xen/XenoLinux to disk, and includes a source code snapshot along with all of the tools required to build it. Booting the CD ============== The Xen VMM is currently fairly h/w specific, but porting new device drivers is relatively straightforward thanks to Xen's Linux driver compatibility layer. The current snapshot supports the following hardware: CPU: Pentium Pro/II/III/IV/Xeon, Athlon (i.e. P6 or newer) SMP supported IDE: Intel PIIX chipset, others will be PIO only (slow) SCSI: Adaptec / Dell PERC Raid (aacraid), megaraid, Adaptec aic7xxx Net: Recommended: Intel e1000, Broadcom BCM57xx (tg3), 3c905 (3c59x) Tested but require extra copies : pcnet32 Untested and also requires extra copies : Intel e100, tulip Because of the demo CD's use of RAM disks, make sure you have plenty of RAM (256MB+). To try out the Demo, boot from CD (you may need to change your BIOS configuration to do this), hit a key on either the keyboard or serial line to pull up the Grub boot menu, then select one of the four boot options: Xen / linux-2.4.22 Xen / linux-2.4.22 using cmdline IP configuration Xen / linux-2.4.22 in "safe mode" linux-2.4.22 The last option is a plain linux kernel that runs on the bare machine, and is included simply to help diagnose driver compatibility problems. The "safe mode" boot option might be useful if you're having problems getting Xen to work with your hardware, as it disables various features such as SMP, and enables some debugging. If you are going for a command line IP config, hit "e" at the grub menu, then edit the "ip=" parameters to reflect your setup e.g. "ip=<ipaddr>::<gateway>:<netmask>::eth0:off". It shouldn't be necessary to set either the nfs server or hostname parameters. Alternatively, once XenoLinux has booted you can login and setup networking with 'dhclient' or 'ifconfig' and 'route' in the normal way. To make things easier for yourself, it's worth trying to arrange for an IP address which is the first in a sequential range of free IP addresses. It's useful to give each VM instance its own public IP address (though it is possible to do NAT or use private addresses), and the configuration files on the CD allocate IP addresses sequentially for subsequent domains unless told otherwise. After selecting the kernel to boot, stand back and watch Xen boot, closely followed by "domain 0" running the XenoLinux kernel. The boot messages are also sent to the serial line (the baud rate can be set on the Xen cmdline, but defaults to 115200), which can be very useful for debugging should anything important scroll off the screen. Xen's startup messages will look quite familiar as much of the hardware initialisation (SMP boot, apic setup) and device drivers are derived from Linux. If everything is well, you should see the linux rc scripts start a bunch of standard services including sshd. Login on the console or via ssh:: username: user root password: xendemo xendemo Once logged in, it should look just like any regular linux box. All the usual tools and commands should work as per usual. It's probably best to start by configuring networking, either with 'dhclient' or manually via ifconfig and route, remembering to edit /etc/resolv.conf if you want DNS. You can start an X server with 'startx'. It defaults to a conservative 1024x768, but you can edit the script for higher resoloutions. The CD contains a load of standard software. You should be able to start Apache, PostgreSQL, Mozilla etc in the normal way, but because everything is running off CD the performance will be very sluggish and you may run out of memory for the 'tmpfs' file system. You may wish to go ahead and install Xen/XenoLinux on your hard drive, either dropping Xen and the XenoLinux kernel down onto a pre-existing Linux distribution, or using the file systems from the CD (which are based on RH9). See the installation instructions later in this document. If your video card requires 'agpgart' then it unfortunately won't yet work with Xen, and you'll only be able to configure a VGA X server. We're working on a fix for this for the next release. If you want to browse the Xen / XenoLinux source, it's all located under /usr/local/src, complete with BitKeeper repository. We've also included source code and configuration information for the various benchmarks we used in the SOSP paper. Starting other domains ====================== There's a web interface for starting and managing other domains (VMs), but since we generally use the command line tools they're probably rather better debugged at present. The key command is 'xenctl' which lives in /usr/local/bin and uses /etc/xenctl.xml for its default configuration. Run 'xenctl' without any arguments to get a help message. Note that xenctl is a java front end to various underlying internal tools written in C (xi_*). Running off CD, it seems to take an age to start... Abyway, the first thing to do is to set up a window in which you will receive console output from other domains. Console output will arrive as UDP packets destined for 169.254.1.0, so its necessary to setup an alias on eth0. The easiest way to do this is to run: xen_nat_enable This also inserts a few NAT rules into "domain0", in case you'll be starting other domains without their own IP addresses. Alternatively, just do "ifconfig eth0:0 169.254.1.0 up". NB: The intention is that in future Xen will do NAT itsel (actually RSIP), but this is part of a larger work package that isn't stable enough to release. Next, run a the xen UDP console displayer: xen_read_console & As mentioned above, xenctl uses /etc/xenctl.xml as its default configuration. The directory contains two different configs depending on whether you want to use NAT, or multiple sequential external IPs (it's possible to override any of the parameters on the command line if you want to set specific IPs, etc). The default configuration file supports NAT. To change to use multiple IPs: cp /etc/xenctl.xml-publicip /etc/xenctl.xml A sequence of commands must be given to xenctl to start a new domain. First a new domain must be created, which requires specifying the initial memory allocation, the kernel image to use, and the kernel command line. As well as the root file system details, you'll need to set the IP address on the command line: since Xen currently doesn't support a virtual console for domains >1, you won't be able to log to your new domain unless you've got networking configured and an sshd running! (using dhcp for new domains should work too). After creating the domain, xenctl must be used to grant the domain access to other resources such as physical or virtual disk partions. Then, the domain must be started. These commands can be entered manually, but for convenience, xenctl will also read them from a script and infer which domain number you're referring to (-nX). To use the sample script: xenctl script -f/etc/xen-mynewdom [NB: no space after the -f] You should see the domain booting on your xen_read_console window. The xml defaults start another domain running off the CD, using a separate RAM-based file system for mutable data in root (just like domain 0). The new domain is started with a '4' on the kernel command line to tell 'init' to go to runlevel 4 rather than the default of 3. This is done simply to suppress a bunch of harmless error messages that would otherwise occur when the new (unprivileged) domain tried to access physical hardware resources to try setting the hwclock, system font, run gpm etc. After it's booted, you should be able to ssh into your new domain. If you went for a NATed address, from domain 0 you should be able to ssh into '169.254.1.X' where X is the domain number. If you ran the xen_enable_nat script, a bunch of port redirects have been installed to enable you to ssh in to other domains remotely. To access the new virtual machine remotely, use: ssh -p2201 root@IP.address.Of.Domain0 # use 2202 for domain 2 etc. If you configured the new domain with its own IP address, you should be able to ssh into it directly. "xenctl domain list" provides status information about running domains, though is currently only allowed to be run by domain 0. It accesses /proc/xeno/domains to read this information from Xen. You can also use xenctl to 'stop' (pause) a domain, or 'kill' a domain. You can either kill it nicely by sending a shutdown event and waiting for it to terminate, or blow the sucker away with extreme prejudice. If you want to configure a new domain differently, type 'xenctl' to get a list of arguments, e.g. at the 'xenctl domain new' command line use the "-4" option to set a diffrent IPv4 address. xenctl can be used to set the new kernel's command line, and hence determine what it uses as a root file system, etc. Although the default is to boot in the same manner that domain0 did (using the RAM-based file system for root and the CD for /usr) it's possible to configure any of the following possibilities, for example: * initrd=/boot/initrd init=/linuxrc boot using an initial ram disk, executing /linuxrc (as per this CD) * root=/dev/hda3 ro boot using a standard hard disk partition as root * root=/dev/xvda1 ro boot using a pre-configured 'virtual block device' that will be attached to a virtual disk that previously has had a file system installed on it. * root=/dev/nfs nfsroot=/path/on/server ip=<blah_including server_IP> Boot using an NFS mounted root file system. This could be from a remote NFS server, or from an NFS server running in another domain. The latter is rather a useful option. A typical setup might be to allocate a standard disk partition for each domain and populate it with files. To save space, having a shared read-only usr partition might make sense. Alternatively, you can use 'virtual disks', which are stored as files within a custom file system. "xenctl partitions add" can be used to 'format' a partition with the file system, and then virtual disks can be created with "xenctl vd create". Virtual disks can then be attached to a running domain as a 'virtual block device' using "xenctl vdb create". The virtual disk can optionally be partitioned (e.g. "fdisk /dev/xvda") or have a file system created on it directly (e.g. "mkfs -t ext3 /dev/xvda"). The virtual disk can then be accessed by a virtual block device associated with another domain, and even used as a boot device. Both virtual disks and real partitions should only be shared between domains in a read-only fashion otherwise the linux kernels will obviously get very confused as the file system structure may change underneath them (having the same partition mounted rw twice is a sure fire way to cause irreparable damage)! If you want read-write sharing, export the directory to other domains via NFS from domain0. Troubleshooting Problems ======================== If you have problems booting Xen, there are a number of boot parameters that may be able to help diagnose problems: ignorebiostables Disable parsing of BIOS-supplied tables. This may help with some chipsets that aren't fully supported by Xen. If you specify this option then ACPI tables are also ignored, and SMP support is disabled. nosmp Disable SMP support. This option is implied by 'ignorebiostables'. noacpi Disable ACPI tables, which confuse Xen on some chipsets. This option is implied by 'ignorebiostables'. watchdog Enable NMI watchdog which can report certain failures. noht Disable Hyperthreading. ifname=ethXX Select which Ethernet interface to use. ifname=dummy Don't use any network interface. ser_baud=xxx Set serial line baud rate for console. dom0_mem=xxx Set the initial amount of memory for domain0. It's probably a good idea to join the Xen developer's mailing list on Sourceforge: http://lists.sourceforge.net/lists/listinfo/xen-devel About The Xen Demo CD ===================== The purpose of the Demo CD is to distribute a snapshot of Xen's source, and simultaneously provide a convenient means for enabling people to get experience playing with Xen without needing to install it on their hard drive. If you decide to install Xen/XenoLinux you can do so simply by following the installation instructions below -- which essentially involves copying the contents of the CD on to a suitably formated disk partition, and then installing or updating the Grub bootloader. This is a bootable CD that loads Xen, and then a Linux 2.4.22 OS image ported to run on Xen. The CD contains a copy of a file system based on the RedHat 9 distribution that is able to run directly off the CD ("live ISO"), using a "tmpfs" RAM-based file system for root (/etc /var etc). Changes you make to the tmpfs will obviously not be persistent across reboots! Because of the use of a RAM-based file system for root, you'll need plenty of memory to run this CD -- something like 96MB per VM. This is not a restriction of Xen : once you've installed Xen, XenoLinux and the file system images on your hard drive you'll find you can boot VMs in just a few MBs. The CD contains a snapshot of the Xen and XenoLinux code base that we believe to be pretty stable, but lacks some of the features that are currently still work in progress e.g. OS suspend/resume to disk, and various memory management enhancements to provide fast inter-OS communication and sharing of memory pages between OSs. We'll release newer snapshots as required, making use of a BitKeeper repository hosted on http://xen.bkbits.net (follow instructions from the project home page). We're obviously grateful to receive any bug fixes or other code you can contribute. We suggest you join the xen...@li... mailing list. Installing from the CD ---------------------- If you're installing Xen/XenoLinux onto an existing linux file system distribution, just copy the Xen VMM (/boot/image.gz) and XenoLinux kernels (/boot/xenolinux.gz), then modify the Grub config (/boot/grub/menu.lst or /boot/grub/grub.conf) on the target system. It should work on pretty much any distribution. Xen is a "multiboot" standard boot image. Despite being a 'standard', few boot loaders actually support it. The only two we know of are Grub, and our modified version of linux kexec (for booting off a XenoBoot CD -- PlanetLab have adopted the same boot CD approach). If you need to install grub on your system, you can do so either by building the Grub source tree /usr/local/src/grub-0.93-iso9660-splashimage or by copying over all the files in /boot/grub and then running /sbin/grub and following the usual grub documentation. You'll then need to edit the Grub config file. A typical Grub menu option might look like: title Xen / XenoLinux 2.4.22 kernel /boot/image.gz dom0_mem=131072 ser_baud=115200 noht module /boot/xenolinux.gz root=/dev/sda4 ro console=tty0 The first line specifies which Xen image to use, and what command line arguments to pass to Xen. In this case, we set the maximum amount of memory to allocate to domain0, and the serial baud rate (the default is 9600 baud). We could also disable smp support (nosmp) or disable hyper-threading support (noht). If you have multiple network interface you can use ifname=ethXX to select which one to use. If your network card is unsupported, use ifname=dummy The second line specifies which xenolinux image to use, and the standard linux command line arguments to pass to the kernel. In this case, we're configuring the root partition and stating that it should be mounted read-only (normal practice). If we were booting with an initial ram disk (initrd), then this would require a second "module" line. Installing the file systems from the CD --------------------------------------- If you haven't an existing Linux installation onto which you can just drop down the Xen and XenoLinux images, then the file systems on the CD provide a quick way of doing an install. Choose one or two partitions, depending on whether you want a separate /usr or not. Make file systems on it/them e.g.: mkfs -t ext3 /dev/hda3 [or mkfs -t ext2 /dev/hda3 && tune2fs -j /dev/hda3 if using an old version of mkfs] Next, mount the file system(s) e.g.: mkdir /mnt/root && mount /dev/hda3 /mnt/root [mkdir /mnt/usr && mount /dev/hda4 /mnt/usr] To install the root file system, simply untar /usr/XenDemoCD/root.tar.gz: cd /mnt/root && tar -zxpf /usr/XenDemoCD/root.tar.gz You'll need to edit /mnt/root/etc/fstab to reflect your file system configuration. Changing the password file (etc/shadow) is probably a good idea too. To install the usr file system, copy the file system from CD on /usr, though leaving out the "XenDemoCD" and "boot" directories: cd /usr && cp -a X11R6 etc java libexec root src bin dict kerberos local sbin tmp doc include lib man share /mnt/usr If you intend to boot off these file systems (i.e. use them for domain 0), then you probably want to copy the /usr/boot directory on the cd over the top of the current symlink to /boot on your root filesystem (after deleting the current symlink) i.e.: cd /mnt/root ; rm boot ; cp -a /usr/boot . The XenDemoCD directory is only useful if you want to build your own version of the XenDemoCD (see below). Debugging --------- Xen has a set of debugging features that can be useful to try and figure out what's going on. Hit 'h' on the serial line or ScrollLock-h on the keyboard to get a list of supported commands. If you have a crash you'll likely get a crash dump containing an EIP (PC) which, along with an 'objdump -d image', can be useful in figuring out what's happened. Debug a XenoLinux image just as you would any other Linux kernel. We supply a handy debug terminal program which you can find in /usr/local/src/xen-1.0rc1/xeno.bk/tools/misc/miniterm/ This should be built and executed on another machine that is connected via a null modem cable. Documentation is included. Alternatively, telnet can be used in 'char mode' if the Xen machine is connected to a serial-port server. Description of how the XenDemoCD boots -------------------------------------- 1. Grub is used to load Xen, a XenoLinux kernel, and an initrd (initial ram disk). [The source of the version of Grub used is in /usr/local/src] 2. the init=/linuxrc command line causes linux to execute /linuxrc in the initrd. 3. the /linuxrc file attempts to mount the CD by trying the likely locations : /dev/hd[abcd]. 4. it then creates a 'tmpfs' file system and untars the 'XenDemoCD/root.tar.gz' file into the tmpfs. This contains hopefully all the files that need to be mutable (this would be so much easier if Linux supported 'stacked' or union file systems...) 5. Next, /linuxrc uses the pivot_root call to change the root file system to the tmpfs, with the CD mounted as /usr. 6. It then invokes /sbin/init in the tmpfs and the boot proceeds normally. Building your own version of the XenDemoCD ------------------------------------------ The 'live ISO' version of RedHat is based heavily on Peter Anvin's SuperRescue CD version 2.1.2 and J. McDaniel's Plan-B: http://www.kernel.org/pub/dist/superrescue/v2/ http://projectplanb.org/ Since Xen uses a "multiboot" image format, it was necessary to change the bootloader from isolinux to Grub0.93 with Leonid Lisovskiy's <ll...@pi...> grub.0.93-iso9660.patch The Xen Demo CD contains all of the build scripts that were used to create it, so it is possible to 'unpack' the current iso, modifiy it, then build a new iso. The procedure for doing so is as follows: First, mount either the CD, or the iso image of the CD: mount /dev/cdrom /mnt/cdrom or: mount -o loop xendemo-1.0.iso /mnt/cdrom cd to the directory you want to 'unpack' the iso into then run the unpack script: cd /local/xendemocd /mnt/cdrom/XenDemoCD/unpack-iso.sh The result is a 'build' directory containing the file system tree under the 'root' directory. e.g. /local/xendemocd/build/root To add or remove rpms, its possible to use 'rpm' with the --root option to set the path. For more complex changes, it easiest to boot a machine using using the tree via NFS root. Before doing this, you'll need to edit fstab to comment out the seperate mount of /usr. One thing to watch out for: as part of the CD build process, the contents of the 'rootpatch' tree gets copied over the existing 'root' tree replacing various files. The intention of the rootpatch tree is to contain the files that have been modified from the original RH distribution (e.g. various /etc files). This was done to make it easier to upgrade to newer RH versions in the future. The downside of this is that if you edit an existing file in the root tree you should check that you don't also need to propagate the change to the rootpatch tree to avoid it being overwritten. Once you've made the changes and want to build a new iso, here's the procedure: cd /local/xendemocd/build echo '<put_your_name_here>' > Builder ./make.sh put_your_version_id_here >../buildlog 2>&1 This process can take 30 mins even on a fast machine, but you should eventually end up with an iso image in the build directory. Notes: root - the root of the file system heirarchy as presented to the running system rootpatch - contains files that have been modified from the standard RH, and copied over the root tree as part of the build procedure. irtree - the file system tree that will go into the initrd (initial ram disk) work - a working directory used in the build process usr - this should really be in 'work' as its created as part of the build process. It contains the 'immutable' files that will be served from the CD rather than the tmpfs containing the contents of root.tar.gz. Some files that are normally in /etc or /var that are large and actually unlikely to need changing have been moved into /usr/root and replaced with links. Ian Pratt 9 Sep 2003 |