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.Dd September 10, 2013
.Dt HYPER-V 4
.Os
.Sh NAME
.Nm hv_ata_pci_disengage
.Nd Hyper-V ATA PCI Disengage driver
.Sh SYNOPSIS
To compile this driver into the kernel, place the following lines in
the system kernel configuration file:
.Bd -ragged -offset indent
.Cd "device hyperv"
.Ed
.Sh DESCRIPTION
The
.Nm
driver prevents the native
.Fx
ATA driver from
loading in the presence of Hyper-V.
.Fx
guests running on Hyper-V can take advantage of the Hyper-V Storage
Virtual Consumer
.Pq Xr hv_storvsc 4
for using their IDE devices.
Since the ATA
driver serves IDE devices as well, there is a chance that the ATA driver may
interfere with the operations of
.Xr hv_storvsc 4 .
The
.Nm
driver avoids
conflicts between the ATA driver and
.Xr hv_storvsc 4
by disabling the ATA driver
when the
.Fx
guest is booting.
.Pp
A side effect of disabling the ATA driver is that CDROM may become
inoperational on
.Fx
guest partitions.
If CDROM access is a must then users may use
"set hw.ata.disk_enable=1" at boot time to prevent the ATA driver from being
disabled.
.Sh SEE ALSO
.Xr hv_netvsc 4 ,
.Xr hv_storvsc 4 ,
.Xr hv_utils 4 ,
.Xr hv_vmbus 4
.Sh HISTORY
Support for
.Nm
first appeared in
.Fx 10.0 .
The driver was developed through a joint effort between Citrix Incorporated,
Microsoft Corporation, and Network Appliance Incorporated.
.Sh AUTHORS
.An -nosplit
.Fx
support for
.Nm
was first added by
.An Microsoft BSD Integration Services Team Aq Mt bsdic@microsoft.com .