From nobody Mon May 19 08:24:20 2025 X-Original-To: dev-commits-src-all@mlmmj.nyi.freebsd.org Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2610:1c1:1:606c::19:1]) by mlmmj.nyi.freebsd.org (Postfix) with ESMTP id 4b19hN6H8Vz5wks4; Mon, 19 May 2025 08:24:20 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from mxrelay.nyi.freebsd.org (mxrelay.nyi.freebsd.org [IPv6:2610:1c1:1:606c::19:3]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256 client-signature RSA-PSS (4096 bits) client-digest SHA256) (Client CN "mxrelay.nyi.freebsd.org", Issuer "R11" (verified OK)) by mx1.freebsd.org (Postfix) with ESMTPS id 4b19hN1vXHz3ntb; Mon, 19 May 2025 08:24:20 +0000 (UTC) (envelope-from git@FreeBSD.org) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1747643060; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=uCKkS71WVND73aNS1o9aeH7JNidkvlGUMAPd08aVfPg=; b=XrND96+QHS6+JogMWyJo8NczwAgB27vD1+TyDeoj3w5sC8TzfKxHg+szWotkLYF2tos7WI AIncN/fCnkt+lbktwrFRZb6YIC+aZPxY3bTnSWo686qGh2o6BRR/zUqT+7IBwT1MRKWgI6 mO8vrGhrN57szn0iXEr3GBJ8vhM26Ots1Yq3N+NJpLUEFZYjuYDqZS1sYRYQSZg53e+BRh MM+6iyljvgD0XycoHFPn+uT5oQS8fKSarfOX9veu9bwQfZU92w0wOLkNMbuoSicENFp5WM /W1p5OG6P1cH0ZAFcn6q20TsQhuFqUCRiO/jSd69+ghqSCBBFa9bgFdBW5u2qQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=freebsd.org; s=dkim; t=1747643060; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding; bh=uCKkS71WVND73aNS1o9aeH7JNidkvlGUMAPd08aVfPg=; b=drfMrlAKZeFu6qMv+KbCvZai1hAjeM5QrMPX3BmMeGVaksOwY9kEX7bZrQKWOh+QEixaPW zjq8vzNZ5HR+Z13/rGeCPNjJwV6SlfOMQmUMnpqmLc4Gpow8EMbBz0aszZMRvRYVKRWq77 e5TOJ8fXwkLduw+RX8ONC1aV2lJ8ZwC6PfpQTYviRl3jOfI1RhguREEFqEffZ6GUhWGV4k GBLfzXU1Uwn1H1XXbQrwa5jitdnZAXdztMC54B24oRc2a1xtG4KfymvzGMTflaUwju61Y6 fzetmJTOfc+iuxqYM8sA25e1GjPBA+Dy1QN8veGc8AfxKjkCNmx8gaGwEmy9Pw== ARC-Seal: i=1; s=dkim; d=freebsd.org; t=1747643060; a=rsa-sha256; cv=none; b=FGL5inAlmCs2OVDIHdWxHqCKADPyPQCvr8tbmBSnGIByGNmIQOg7aZudTHGCUT6qqYXF33 m1cQRDijM0750DdKriuFrwYiwOuShW315DCPPn3vV/rs17Doo3fWjGDdvjZZdqDQhcZjcN UX3wImPQ4RYBoV9EOLCewhkHon9v51SP2WwQA1I6P5otAmr2bXg2MZ3a97NBsusJJTJHNW EU3b0qQtatHjl2pTFUspMGyjzjafFAgzi2jC/Xuau3nNbdV3RfdgriO7sOweKCnKEaCNH7 qO4tJj4p2dA0/mkFGr1Io0uExbQUaf8y1IVTgzjQXtZ1tcT1k8hORXmIfA20+g== ARC-Authentication-Results: i=1; mx1.freebsd.org; none Received: from gitrepo.freebsd.org (gitrepo.freebsd.org [IPv6:2610:1c1:1:6068::e6a:5]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (4096 bits) server-digest SHA256) (Client did not present a certificate) by mxrelay.nyi.freebsd.org (Postfix) with ESMTPS id 4b19hN16bJzwpT; Mon, 19 May 2025 08:24:20 +0000 (UTC) (envelope-from git@FreeBSD.org) Received: from gitrepo.freebsd.org ([127.0.1.44]) by gitrepo.freebsd.org (8.18.1/8.18.1) with ESMTP id 54J8OKNa098036; Mon, 19 May 2025 08:24:20 GMT (envelope-from git@gitrepo.freebsd.org) Received: (from git@localhost) by gitrepo.freebsd.org (8.18.1/8.18.1/Submit) id 54J8OKWF098033; Mon, 19 May 2025 08:24:20 GMT (envelope-from git) Date: Mon, 19 May 2025 08:24:20 GMT Message-Id: <202505190824.54J8OKWF098033@gitrepo.freebsd.org> To: src-committers@FreeBSD.org, dev-commits-src-all@FreeBSD.org, dev-commits-src-branches@FreeBSD.org From: Roger Pau =?utf-8?Q?Monn=C3=A9?= Subject: git: 7dc0a9fa76a8 - stable/14 - xen: improve man (4) page List-Id: Commit messages for all branches of the src repository List-Archive: https://lists.freebsd.org/archives/dev-commits-src-all List-Help: List-Post: List-Subscribe: List-Unsubscribe: X-BeenThere: dev-commits-src-all@freebsd.org Sender: owner-dev-commits-src-all@FreeBSD.org MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit X-Git-Committer: royger X-Git-Repository: src X-Git-Refname: refs/heads/stable/14 X-Git-Reftype: branch X-Git-Commit: 7dc0a9fa76a8df6dfaf26ff36a11aa9fe060a201 Auto-Submitted: auto-generated The branch stable/14 has been updated by royger: URL: https://cgit.FreeBSD.org/src/commit/?id=7dc0a9fa76a8df6dfaf26ff36a11aa9fe060a201 commit 7dc0a9fa76a8df6dfaf26ff36a11aa9fe060a201 Author: Roger Pau Monné AuthorDate: 2024-01-09 09:26:06 +0000 Commit: Roger Pau Monné CommitDate: 2025-05-19 08:23:04 +0000 xen: improve man (4) page Update the xen(4) man page to reflect the current support status. Reported by: kevans Reviewed by: bcr kevans imp Differential revision: https://reviews.freebsd.org/D43373 (cherry picked from commit 82126ef92fdb3c13a67ad44d33c0fe6ea479c01a) --- share/man/man4/xen.4 | 74 +++++++++++++++++++++++----------------------------- 1 file changed, 33 insertions(+), 41 deletions(-) diff --git a/share/man/man4/xen.4 b/share/man/man4/xen.4 index 6660ab3c268b..15312866dae6 100644 --- a/share/man/man4/xen.4 +++ b/share/man/man4/xen.4 @@ -26,19 +26,19 @@ .\" OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF .\" SUCH DAMAGE. .\" -.Dd April 30, 2015 +.Dd January 8, 2024 .Dt XEN 4 .Os .Sh NAME .Nm xen -.Nd Xen Hypervisor Guest (DomU) Support +.Nd Xen Hypervisor Support .Sh SYNOPSIS -To compile hardware-assisted virtualization (HVM) Xen guest support with -para-virtualized drivers into an amd64 or i386 kernel, -place the following lines in your kernel configuration file: -.Bd -ragged -offset indent -.Cd "options XENHVM" -.Cd "device xenpci" +FreeBSD supports running both as a Xen guest and host on amd64 hardware. +Guest support is limited to HVM and PVH modes, while host support is limited to +PVH mode only. +.Pp +Xen support is built by default in the i386 and amd64 GENERIC kernels; note +however that host mode is only available on amd64. .Ed .Sh DESCRIPTION The Xen Hypervisor allows multiple virtual machines to be run on a single @@ -52,20 +52,18 @@ to access resources such as virtual network interfaces and disk devices. .Pp With later instruction set extensions from AMD and Intel to support fully virtualizable instructions, unmodified virtual memory systems can also be -supported; this is referred to as hardware-assisted virtualization (HVM). +supported; this is referred to as hardware-assisted virtualization (HVM and PVH). HVM configurations may either rely on transparently emulated hardware peripherals, or para-virtualized drivers, which are aware of virtualization, and hence able to optimize certain behaviors to improve performance or semantics. +PVH configurations rely on para-virtualized drivers exclusively for IO. .Pp .Fx -supports hardware-assisted virtualization (HVM) on both i386 and amd64 -kernels. -.Pp Para-virtualized device drivers are required in order to support certain functionality, such as processing management requests, returning idle physical memory pages to the hypervisor, etc. -.Ss Xen DomU device drivers +.Ss Xen device drivers These para-virtualized drivers are supported: .Bl -hang -offset indent -width blkfront .It Nm balloon @@ -87,6 +85,10 @@ suspend, crash, and halt requests. Expose Xen events via the .Pa /dev/xen/evtchn special device. +.It Nm gntdev +Allow access to the grant table interface via the +.Pa /dev/xen/gntdev +special device. .It Nm netback Export local network interfaces to other Xen domains where they can be imported via @@ -94,35 +96,30 @@ imported via .It Nm netfront Import network interfaces from other Xen domains as local network interfaces, which may be used for IPv4, IPv6, etc. -.It Nm pcifront -Allow physical PCI devices to be passed through into a PV domain. +.It Nm privcmd +Allow issuing hypercalls via the +.Pa /dev/xen/privcmd +special device. +.It Nm timer +Implementation of a one-shot high resolution per-CPU timer using the hypercall +interface. +.It Nm acpi cpu +When running as a host forwards power management related information from ACPI +to the hypervisor for better performance management. .It Nm xenpci Represents the Xen PCI device, an emulated PCI device that is exposed to HVM domains. This device allows detection of the Xen hypervisor, and provides interrupt and shared memory services required to interact with the hypervisor. +.It Nm xenstore +Information storage space shared between domains. .El -.Ss Performance considerations -In general, PV drivers will perform better than emulated hardware, and are -the recommended configuration for HVM installations. -.Pp -Using a hypervisor introduces a second layer of scheduling that may limit the -effectiveness of certain -.Fx -scheduling optimisations. -Among these is adaptive locking, which is no longer able to determine whether -a thread holding a lock is in execution. -It is recommended that adaptive locking be disabled when using Xen: -.Bd -unfilled -offset indent -.Cd "options NO_ADAPTIVE_MUTEXES" -.Cd "options NO_ADAPTIVE_RWLOCKS" -.Cd "options NO_ADAPTIVE_SX" -.Ed .Sh HISTORY Support for .Nm first appeared in .Fx 8.1 . +Support for host mode was added in 11.0 . .Sh AUTHORS .An -nosplit .Fx @@ -133,15 +130,10 @@ and Further refinements were made by .An Justin Gibbs Aq Mt gibbs@FreeBSD.org , .An Adrian Chadd Aq Mt adrian@FreeBSD.org , +.An Colin Percival Aq Mt cperciva@FreeBSD.org , and -.An Colin Percival Aq Mt cperciva@FreeBSD.org . +.An Roger Pau Monné Aq Mt royger@FreeBSD.org . This manual page was written by -.An Robert Watson Aq Mt rwatson@FreeBSD.org . -.Sh BUGS -.Fx -is only able to run as a Xen guest (DomU) and not as a Xen host (Dom0). -.Pp -As of this release, Xen PV DomU support is not heavily tested; instability -has been reported during VM migration of PV kernels. -.Pp -Certain PV driver features, such as the balloon driver, are under-exercised. +.An Robert Watson Aq Mt rwatson@FreeBSD.org , +and +.An Roger Pau Monné Aq Mt royger@FreeBSD.org .