diff --git a/share/man/man4/xen.4 b/share/man/man4/xen.4 index 57adc8aba246..6470635e391c 100644 --- a/share/man/man4/xen.4 +++ b/share/man/man4/xen.4 @@ -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.