Date: Fri, 17 Dec 2010 01:30:56 +0000 (UTC) From: Robert Watson <rwatson@FreeBSD.org> To: src-committers@freebsd.org, svn-src-all@freebsd.org, svn-src-head@freebsd.org Subject: svn commit: r216497 - head/share/man/man4 Message-ID: <201012170130.oBH1Uuos016660@svn.freebsd.org>
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Author: rwatson Date: Fri Dec 17 01:30:56 2010 New Revision: 216497 URL: http://svn.freebsd.org/changeset/base/216497 Log: Clarifications of a number of points in xen.4, and some additional device driver information from gibbs@. MFC after: 3 days Modified: head/share/man/man4/xen.4 Modified: head/share/man/man4/xen.4 ============================================================================== --- head/share/man/man4/xen.4 Thu Dec 16 23:28:20 2010 (r216496) +++ head/share/man/man4/xen.4 Fri Dec 17 01:30:56 2010 (r216497) @@ -86,17 +86,18 @@ the amd64 architecture, and require Para-virtualized device drivers are required in order to support certain functionality, such as processing management requests, returning idle physical memory pages to the hypevisor, etc. -.Ss Para-virtualized drivers +.Ss Xen DomU device drivers Adding .Cd "options xenpci" -to the kernel configuration enables the Xen para-virtualized drivers: +to the kernel configuration enables the Xen administrative or +para-virtualized drivers: .Bl -hang -offset indent -width blkfront .It Nm balloon Allow physical memory pages to be returned to the hypervisor as a result of manual tuning or automatic policy. .It Nm blkback -Exports local block devices to other Xen domains where they can then be -imported via +Exports local block devices or files to other Xen domains where they can +then be imported via .Nm blkfront . .It Nm blkfront Import block devices from other Xen domains as local block devices, to be @@ -118,13 +119,16 @@ imported via Import network interfaces from other Xen domains as local network interfaces, which may be used for IPv4, IPv6, etc. .It Nm pcifront -No description. +Allow physical PCI devices to be passed through into a PV domain. .It Nm xenpci -No description. +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. .El -.Ss Performance +.Ss Performance considerations In general, PV drivers will perform better than emulated hardware, and are -the recommended configuration. +the recommended configuration for HVM installations. .Pp Using a hypervisor introduces a second layer of scheduling that may limit the effectiveness of certain @@ -168,7 +172,8 @@ amd64. .Pp Para-virtualized drivers under hardware-assisted virtualization (HVM) kernel are only supported on amd64, not i386. -.P -As of this release, Xen DomU support is not heavily tested; instability has -been reported during VM migration of PV kernels, and certain PV driver -features, such as the balloon driver, are under-exercised. +.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.
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