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Clarifications of a number of points in xen.4, and some additional device

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driver information from gibbs@.

MFC after:	3 days
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Robert Watson 2010-12-17 01:30:56 +00:00
parent fa0951d63a
commit cd66b53aee
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=216497
1 changed files with 17 additions and 12 deletions
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29
share/man/man4/xen.4
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@ -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.