svn commit: r216497 - head/share/man/man4
rwatson at FreeBSD.org
Fri Dec 17 01:30:56 UTC 2010
Date: Fri Dec 17 01:30:56 2010
New Revision: 216497
Clarifications of a number of points in xen.4, and some additional device
driver information from gibbs at .
MFC after: 3 days
--- 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
.Cd "options xenpci"
-to the kernel configuration enables the Xen para-virtualized drivers:
+to the kernel configuration enables the Xen administrative or
.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
+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
+Allow physical PCI devices to be passed through into a PV domain.
.It Nm xenpci
+Represents the Xen PCI device, an emulated PCI device that is exposed to
+This device allows detection of the Xen hypervisor, and provides interrupt
+and shared memory services required to interact with the hypervisor.
+.Ss Performance considerations
In general, PV drivers will perform better than emulated hardware, and are
-the recommended configuration.
+the recommended configuration for HVM installations.
Using a hypervisor introduces a second layer of scheduling that may limit the
effectiveness of certain
@@ -168,7 +172,8 @@ amd64.
Para-virtualized drivers under hardware-assisted virtualization (HVM) kernel
are only supported on amd64, not i386.
-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.
+As of this release, Xen PV DomU support is not heavily tested; instability
+has been reported during VM migration of PV kernels.
+Certain PV driver features, such as the balloon driver, are under-exercised.
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