--- wikisrc/ports/xen/howto.mdwn 2015/03/05 14:04:55 1.95 +++ wikisrc/ports/xen/howto.mdwn 2016/12/20 03:50:04 1.104 @@ -49,7 +49,8 @@ specific PCI devices can be made availab of the dom0. This can be useful to let a domU run X11, or access some network interface or other peripheral. -NetBSD used to support Xen2; this has been removed. +NetBSD 6 and earlier supported Xen 2; support was removed fro NetBSD +7. Xen 2 has been removed from pkgsrc. Prerequisites ------------- @@ -81,19 +82,39 @@ xenkernel and xentools. We will refer o but note that both packages must be installed together and must have matching versions. -xenkernel3 and xenkernel33 provide Xen 3.1 and 3.3. These no longer -receive security patches and should not be used. Xen 3.1 supports PCI -passthrough. Xen 3.1 supports non-PAE on i386. - -xenkernel41 provides Xen 4.1. This is no longer maintained by Xen, -but as of 2014-12 receives backported security patches. It is a -reasonable although trailing-edge choice. +xenkernel3 provides Xen 3.1. It is no longer maintained by Xen, and the last applied security patch was in +2011. Thus, it should not be used. It supports PCI passthrough, +which is why people use it anyway. Xen 3.1 supports i386, both PAE and +non-PAE. + +xenkernel33 provides Xen 3.3. It is no longer maintained by Xen, and +the last applied security patch was in 2012. Thus, it should not be +used. Xen 3.3 supports i386, but only in PAE mode. There are no good +reasons to run this version. + +xenkernel41 provides Xen 4.1. It is no longer maintained by Xen, but +as of 2016-11 received backported security patches. Xen 4.1 supports +i386, but only in PAE mode. There are no good reasons to run this +version. + +xenkernel42 provides Xen 4.2. It is no longer maintained by Xen, but +as of 2016-11 received backported security patches. Xen 4.2 supports +i386, but only in PAE mode. The only reason to run this is if you +need to use xm instead of xl, or if you need to run an i386 dom0 +(because your hardware is i386 only). + +xenkernel45 provides Xen 4.5. It is no longer maintained by Xen, but +as of 2016-11 it received security patches. Xen 4.5 requires an amd64 +dom0, but domUs can be amd64 or i386 PAE. TODO: It is either a +conservative choice or somewhat old. + +xenkernel45 provides Xen 4.6. It is new to pkgsrc in 2016-05. It is +no longer maintained by Xen, but as of 2016-11 it received security +patches. Xen 4.6 requires an amd64 dom0, but domUs can be amd64 or +i386 PAE. TODO: It is either a somewhat aggressive choice or the +standard choice -xenkernel42 provides Xen 4.2. This is maintained by Xen, but old as -of 2014-12. - -xenkernel45 provides Xen 4.5. This is new to pkgsrc as of 2015-01 and -not yet recommended for other than experimental/testing use. +See also the [Xen Security Advisory page](http://xenbits.xen.org/xsa/). Ideally newer versions of Xen will be added to pkgsrc. @@ -128,19 +149,28 @@ Architecture ------------ Xen itself can run on i386 or amd64 machines. (Practically, almost -any computer where one would want to run Xen supports amd64.) If -using an i386 NetBSD kernel for the dom0, PAE is required (PAE -versions are built by default). While i386 dom0 works fine, amd64 is -recommended as more normal. +any computer where one would want to run Xen today supports amd64.) + +Xen, the dom0 kernel, and each domU kernel can be either i386 or +amd64. When building a xenkernel package, one obtains i386 on an i386 +host, and amd64 on an amd64 host. If the xen kernel is i386, then the +dom0 kernel and all domU kernels must be i386. With an amd64 xen +kernel, an amd64 dom0 kernel is known to work, and an i386 dom0 kernel +should in theory work. An amd64 xen/dom0 is known to support both +i386 and amd64 domUs. + +i386 dom0 and domU kernels must be PAE (except for Xen 3.1); these are +built by default. (Note that emacs (at least) fails if run on i386 +with PAE when built without, and vice versa, presumably due to bugs in +the undump code.) + +Because of the above, the standard approach is to use amd64 for the +dom0. Xen 4.2 is the last version to support i386 as a host. TODO: Clarify -if this is about the CPU having to be amd64, or about the dom0 kernel -having to be amd64. +if this is about the CPU, the xen kernel, or the dom0 kernel having to +be amd64. -One can then run i386 domUs and amd64 domUs, in any combination. If -running an i386 NetBSD kernel as a domU, the PAE version is required. -(Note that emacs (at least) fails if run on i386 with PAE when built -without, and vice versa, presumably due to bugs in the undump code.) Stability --------- @@ -357,67 +387,47 @@ Xen logs will be in /var/log/xen. Now, you have a system that will boot Xen and the dom0 kernel, but not do anything else special. Make sure that you have rebooted into Xen. There will be no domUs, and none can be started because you still have -to configure the dom0 tools. The daemons which should be run vary -with Xen version and with whether one is using xm or xl. Note that -xend is for supporting "xm", and should only be used if you plan on -using "xm". Do NOT enable xend if you plan on using "xl" as it will -cause problems. Running xl without xencommons=YES (and starting it) -will result in a hang (so don't do that; follow the HOWTO!). +to configure the dom0 daemons. -The installation of NetBSD should already have created devices for xen -(xencons, xenevt), but if they are not present, create them: - - cd /dev && sh MAKEDEV xen +The daemons which should be run vary with Xen version and with whether +one is using xm or xl. The Xen 3.1 and 3.3 packages use xm. Xen 4.1 +and higher packages use xl. While is is possible to use xm with some +4.x versions (TODO: 4.1 and 4.2?), the pkgsrc-provided rc.d scripts do +not support this as of 2014-12-26, and thus the HOWTO does not support +it either. (Make sure your packages are reasonably recent.) -TODO: Give 3.1 advice (or remove it from pkgsrc). - -For 3.3 (and thus xm), add to rc.conf (but note that you should have -installed 4.1 or 4.2): +For "xm" (3.1 and 3.3), you should enable xend and xenbackendd (but +note that you should be using 4.x): xend=YES xenbackendd=YES -For 4.1 (and thus xm; xl is believed not to work well), add to rc.conf: - - xencommons=YES - xend=YES - -(If you are using xentools41 from before 2014-12-26, change -rc.d/xendomains to use xm rather than xl.) - -For 4.2 with xm, add to rc.conf +For "xl" (4.x), you should enabled xend and xencommons (xenstored). +Trying to boot 4.x without xencommons=YES will result in a hang; it is +necessary to hig ^C on the console to let the machine finish booting. +TODO: explain why xend is installed by the package. xencommons=YES - xend=YES - -For 4.2 with xl, add to rc.conf: - - xencommons=YES - TODO: explain if there is a xend replacement -For 4.5 (and thus with xl), add to rc.conf: +The installation of NetBSD should already have created devices for xen +(xencons, xenevt), but if they are not present, create them: - xencommons=YES - TODO: explain if there is a xend replacement + cd /dev && sh MAKEDEV xen TODO: Recommend for/against xen-watchdog. After you have configured the daemons and either started them (in the order given) or rebooted, use xm or xl to inspect Xen's boot messages, -available resources, and running domains. An example with xm follows: +available resources, and running domains. An example with xl follows: - # xm dmesg + # xl dmesg [xen's boot info] - # xm info + # xl info [available memory, etc.] - # xm list + # xl list Name Id Mem(MB) CPU State Time(s) Console Domain-0 0 64 0 r---- 58.1 -With xl, the commands are the same, and the output may be slightly -different. TODO: add example output for xl before the xm example, -after confirming on 4.2 and resolving the TODO about rc.conf. - ### Issues with xencommons xencommons starts xenstored, which stores data on behalf of dom0 and @@ -502,7 +512,7 @@ section. TODO: actually do this and fix it if necessary. -Updating Xen versions +Upgrading Xen versions --------------------- Updating Xen is conceptually not difficult, but can run into all the @@ -510,10 +520,36 @@ issues found when installing Xen. Assum remove the xenkernel41 and xentools41 packages and install the xenkernel42 and xentools42 packages. Copy the 4.2 xen.gz to /. -Ensure that the contents of /etc/rc.d/xen* are correct. Enable the -correct set of daemons. Ensure that the domU config files are valid -for the new version. +Ensure that the contents of /etc/rc.d/xen* are correct. Specifically, +they must match the package you just installed and not be left over +from some previous installation. + +Enable the correct set of daemons; see the configuring section above. +(Upgrading from 3.x to 4.x without doing this will result in a hang.) + +Ensure that the domU config files are valid for the new version. +Specifically: remove autorestart=True, and ensure that disks are +specified with numbers as the second argument, as the examples above +show, and not NetBSD device names. + +Hardware known to work +---------------------- + +Arguably, this section is misplaced, and there should be a page of +hardware that runs NetBSD/amd64 well, with the mostly-well-founded +assumption that NetBSD/xen runs fine on any modern hardware that +NetBSD/amd64 runs well on. Until then, we give motherboard/CPU/RAM +triples to aid those choosing a motherboard. Note that Xen systems +usually do not run X, so a listing here does not imply that X works at +all. + + Supermicro X9SRL-F, Xeon E5-1650 v2, 96 GiB ECC + Supermicro ??, Atom C2758 (8 core), 32 GiB ECC + ASUS M5A78L-M/USB3 AM3+ microATX, AMD Piledriver X8 4000MHz, 16 GiB ECC + +Older hardware: + Intel D915GEV, Pentium4 CPU 3.40GHz, 4GB 533MHz Synchronous DDR2 Running Xen under qemu ----------------------