--- wikisrc/ports/xen/howto.mdwn 2020/11/15 14:59:54 1.185 +++ wikisrc/ports/xen/howto.mdwn 2021/02/26 18:39:20 1.190 @@ -27,6 +27,9 @@ xen itself). It also addresses how to r and how to deal with having a domU in a Xen environment run by someone else and/or not running NetBSD. +There are many choices one can make; the HOWTO recommends the standard +approach and limits discussion of alternatives in many cases. + ## Guest Styles Xen supports different styles of guests. @@ -112,7 +115,7 @@ NetBSD, when run as a domU, can and does Note: NetBSD support is called XEN3. However, it does support Xen 4, because the hypercall interface has remained identical. -# Creating a dom0 +# Creating a NetBSD dom0 In order to install a NetBSD as a dom0, one must first install a normal NetBSD system, and then pivot the install to a dom0 install by changing @@ -126,16 +129,19 @@ In 2018-05, trouble booting a dom0 was r [Install NetBSD/amd64](/guide/inst/) just as you would if you were not using Xen. +Therefore, use the most recent release, or a build from the most recent stable branch. ## Installation of Xen -We will consider that you chose to use Xen 4.13, with NetBSD/amd64 as -dom0. In the dom0, install xenkernel48 and xentools48 from pkgsrc. +Use the most recent version of Xen in pkgsrc, unless the DESCR says that it is not suitable. +Therefore, choose 4.13. +In the dom0, install xenkernel413 and xentools413 from pkgsrc. -Once this is done, install the Xen kernel itself: +Once this is done, copy the Xen kernel from where pkgsrc puts it to +where the boot process will be able to find it: [[!template id=programlisting text=""" -# cp /usr/pkg/xen48-kernel/xen.gz / +# cp -p /usr/pkg/xen413-kernel/xen.gz / """]] Then, place a NetBSD XEN3_DOM0 kernel in the `/` directory. Such kernel @@ -143,7 +149,7 @@ can either be compiled manually, or down example at: [[!template id=programlisting text=""" -ftp.netbsd.org/pub/NetBSD/NetBSD-8.0/amd64/binary/kernel/netbsd-XEN3_DOM0.gz +ftp.netbsd.org/pub/NetBSD/NetBSD-9.1/amd64/binary/kernel/netbsd-XEN3_DOM0.gz """]] Add a line to /boot.cfg to boot Xen: @@ -153,7 +159,13 @@ menu=Xen:load /netbsd-XEN3_DOM0.gz conso """]] This specifies that the dom0 should have 512MB of ram, leaving the rest -to be allocated for domUs. To use a serial console, use: +to be allocated for domUs. + +NB: This says add, not replace, so that you will be able to boot a +NetBSD kernel without Xen. Once Xen boots ok, you may want to set it +as default. + +To use a serial console, add settings as follows: [[!template id=filecontent name="/boot.cfg" text=""" menu=Xen:load /netbsd-XEN3_DOM0.gz;multiboot /xen.gz dom0_mem=512M console=com1 com1=9600,8n1 @@ -173,23 +185,22 @@ more) and to pin that vcpu to a physical and other than dom0 memory and max_vcpus, they are generally not necessary. -Copy the boot scripts into `/etc/rc.d`: - -[[!template id=programlisting text=""" -# cp /usr/pkg/share/examples/rc.d/xen* /etc/rc.d/ -"""]] +Ensure that the boot scripts installed in +`/usr/pkg/share/examples/rc.d` are in `/etc/rc.d`, either because you +have `PKG_RCD_SCRIPTS=yes`, or manually. (This is not special to Xen, +but a normal part of pkgsrc usage.) -Enable `xencommons`: +Set `xencommons=YES` in rc.conf: [[!template id=filecontent name="/etc/rc.conf" text=""" xencommons=YES """]] +\todo Recommend for/against xen-watchdog. + Now, reboot so that you are running a DOM0 kernel under Xen, rather than GENERIC without Xen. -TODO: Recommend for/against xen-watchdog. - Once the reboot is done, use `xl` to inspect Xen's boot messages, available resources, and running domains. For example: @@ -216,16 +227,7 @@ the state when the new xenstored starts. make this work, one should not expect to be able to restart xenstored (and thus xencommons). There is currently no reason to expect that this will get fixed any time soon. - -## anita (for testing NetBSD) - -With the setup so far, one should be able to run -anita (see pkgsrc/misc/py-anita) to test NetBSD releases, by doing (as -root, because anita must create a domU): - -[[!template id=programlisting text=""" -anita --vmm=xl test file:///usr/obj/i386/ -"""]] +\todo Confirm if this is still true in 2020. ## Xen-specific NetBSD issues @@ -241,6 +243,16 @@ options as GENERIC. While it is debatab bug, users should be aware of this and can simply add missing config items if desired. +Finally, there have been occasional reports of trouble with X11 +servers in NetBSD as a dom0. + +## Updating Xen in a dom0 + +Basically, update the xenkernel and xentools packages and copy the new +Xen kernel into place, and reboot. This procedure should be usable to +update to a new Xen release, but the reader is reminded that having a +non-Xen boot methods was recommended earlier. + ## Updating NetBSD in a dom0 This is just like updating NetBSD on bare hardware, assuming the new @@ -251,43 +263,17 @@ and adjusts `/etc`. Note that one must update both the non-Xen kernel typically used for rescue purposes and the DOM0 kernel used with Xen. -## Converting from grub to /boot +## anita (for testing NetBSD) -These instructions were used to convert a system from -grub to /boot. The system was originally installed in February of -2006 with a RAID1 setup and grub to boot Xen 2, and has been updated -over time. Before these commands, it was running NetBSD 6 i386, Xen -4.1 and grub, much like the message linked earlier in the grub -section. +With a NetBSD dom0, even without any domUs, one should be able to run +anita (see pkgsrc/misc/py-anita) to test NetBSD releases, by doing (as +root, because anita must create a domU): [[!template id=programlisting text=""" -# Install MBR bootblocks on both disks. -fdisk -i /dev/rwd0d -fdisk -i /dev/rwd1d -# Install NetBSD primary boot loader (/ is FFSv1) into RAID1 components. -installboot -v /dev/rwd0d /usr/mdec/bootxx_ffsv1 -installboot -v /dev/rwd1d /usr/mdec/bootxx_ffsv1 -# Install secondary boot loader -cp -p /usr/mdec/boot / -# Create boot.cfg following earlier guidance: -menu=Xen:load /netbsd-XEN3PAE_DOM0.gz console=pc;multiboot /xen.gz dom0_mem=512M -menu=Xen.ok:load /netbsd-XEN3PAE_DOM0.ok.gz console=pc;multiboot /xen.ok.gz dom0_mem=512M -menu=GENERIC:boot -menu=GENERIC single-user:boot -s -menu=GENERIC.ok:boot netbsd.ok -menu=GENERIC.ok single-user:boot netbsd.ok -s -menu=Drop to boot prompt:prompt -default=1 -timeout=30 -"""]] - -## Upgrading Xen versions - -Minor version upgrades are trivial. Just rebuild/replace the -xenkernel version and copy the new xen.gz to `/` (where `/boot.cfg` -references it), and reboot. +anita --vmm=xl test file:///usr/obj/i386/ +"""]] -#Unprivileged domains (domU) +# Unprivileged domains (domU) This section describes general concepts about domUs. It does not address specific domU operating systems or how to install them. The @@ -329,6 +315,8 @@ are stored in files and Xen attaches the dom0 on domain creation. The system treats xbd0 as the boot device without needing explicit configuration. +There is not type line; that implicitly defines a pv domU. + By convention, domain config files are kept in `/usr/pkg/etc/xen`. Note that "xl create" takes the name of a config file, while other commands take the name of a domain. @@ -397,11 +385,7 @@ Note that NetBSD by default creates only than 4 total virtual disks at a time, run e.g. "./MAKEDEV vnd4" in the dom0. -Note that NetBSD by default creates only xbd[0123]. If you need more -virtual disks in a domU, run e.g. "./MAKEDEV xbd4" in the domU. - -Virtual Networking ------------------- +## Virtual Networking Xen provides virtual Ethernets, each of which connects the dom0 and a domU. For each virtual network, there is an interface "xvifN.M" in @@ -433,8 +417,7 @@ The MAC address specified is the one use domain. The interface in dom0 will use this address XOR'd with 00:00:00:01:00:00. Random MAC addresses are assigned if not given. -Starting domains automatically ------------------------------- +## Starting domains automatically To start domains `domU-netbsd` and `domU-linux` at boot and shut them down cleanly on dom0 shutdown, add the following in rc.conf: @@ -443,14 +426,14 @@ down cleanly on dom0 shutdown, add the f xendomains="domU-netbsd domU-linux" """]] -# Creating a domU +# domU setup for specific systems Creating domUs is almost entirely independent of operating system. We -have already presented the basics of config files. Note that you must -have already completed the dom0 setup so that "xl list" works. +have already presented the basics of config files in the previous system. + +Of course, this section presumes that you have a working dom0. -Creating a NetBSD PV domU --------------------------- +## Creating a NetBSD PV domU See the earlier config file, and adjust memory. Decide on how much storage you will provide, and prepare it (file or LVM). @@ -459,14 +442,14 @@ While the kernel will be obtained from t file should be present in the domU as /netbsd so that tools like savecore(8) can work. (This is helpful but not necessary.) -The kernel must be specifically for Xen and for use as a domU. The -i386 and amd64 provide the following kernels: +The kernel must be specifically built for Xen, to use PV interfacesas +a domU. NetBSD release builds provide the following kernels: i386 XEN3PAE_DOMU amd64 XEN3_DOMU This will boot NetBSD, but this is not that useful if the disk is -empty. One approach is to unpack sets onto the disk outside of xen +empty. One approach is to unpack sets onto the disk outside of Xen (by mounting it, just as you would prepare a physical disk for a system you can't run the installer on). @@ -486,11 +469,11 @@ line should be used in the config file. After booting the domain, the option to install via CDROM may be selected. The CDROM device should be changed to `xbd1d`. -Once done installing, "halt -p" the new domain (don't reboot or halt, +Once done installing, "halt -p" the new domain (don't reboot or halt: it would reload the INSTALL_XEN3_DOMU kernel even if you changed the config file), switch the config file back to the XEN3_DOMU kernel, and start the new domain again. Now it should be able to use "root on -xbd0a" and you should have a, functional NetBSD domU. +xbd0a" and you should have a functional NetBSD domU. TODO: check if this is still accurate. When the new domain is booting you'll see some warnings about *wscons* @@ -522,8 +505,10 @@ not really a Xen-specific issue, but bec obtained from the dom0, it is far more likely to be out of sync or missing with Xen.) -Creating a Linux domU ---------------------- +Note that NetBSD by default creates only xbd[0123]. If you need more +virtual disks in a domU, run e.g. "./MAKEDEV xbd4" in the domU. + +## Creating a Linux domU Creating unprivileged Linux domains isn't much different from unprivileged NetBSD domains, but there are some details to know. @@ -577,15 +562,13 @@ Use type='pvh'. \todo Explain where the kernel comes from. -Creating a Solaris domU ------------------------ +## Creating a Solaris domU See possibly outdated [Solaris domU instructions](/ports/xen/howto-solaris/). -PCI passthrough: Using PCI devices in guest domains ---------------------------------------------------- +## PCI passthrough: Using PCI devices in guest domains NB: PCI passthrough only works on some Xen versions and as of 2020 it is not clear that it works on any version in pkgsrc. Reports @@ -658,9 +641,20 @@ note that only the "xpci" lines are unus cd* at scsibus? target ? lun ? # SCSI CD-ROM drives -# Specific Issues +# Miscellaneous Information + +## Nesting under Linux KVM + +It is possible to run a Xen and a NetBSD dom0 under Linux KVM. One +can enable virtio in the dom0 for greater speed. + +## Other nesting + +In theory, any full emulation should be able to run Xen and a NetBSD +dom0. The HOWTO does not currently have information about Xen XVM +mode, nvmm, qemu, Virtualbox, etc. -## domU +## NetBSD 5 as domU [NetBSD 5 is known to panic.](http://mail-index.netbsd.org/port-xen/2018/04/17/msg009181.html) (However, NetBSD 5 systems should be updated to a supported version.)