---
name: "hv_ata_pci_disengage"
section: "4freebsd"
platform: "linux"
package: "freebsd-manpages"
version: "11.0-1"
release: "Debian 9 (Stretch)"
platforms: ["linux"]
url: "https://new.carta.tech/hv_ata_pci_disengage"
---

# hv\_ata\_pci\_disengage(4freebsd)

Hyper-V ATA PCI Disengage driver

## NAME

**hv\_ata\_pci\_disengage** – Hyper-V ATA PCI Disengage driver

## SYNOPSIS

To compile this driver into the kernel, place the following lines in the system kernel configuration file:

**device hyperv**

## DESCRIPTION

The **hv\_ata\_pci\_disengage** driver prevents the native FreeBSD ATA driver from loading in the presence of Hyper-V. FreeBSD guests running on Hyper-V can take advantage of the Hyper-V Storage Virtual Consumer ([hv\_storvsc(4)](/hv_storvsc/4.md)) 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 [hv\_storvsc(4)](/hv_storvsc/4.md). The **hv\_ata\_pci\_disengage** driver avoids conflicts between the ATA driver and [hv\_storvsc(4)](/hv_storvsc/4.md) by disabling the ATA driver when the FreeBSD guest is booting.

A side effect of disabling the ATA driver is that CDROM may become inoperational on FreeBSD 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.

## SEE ALSO

[hv\_netvsc(4)](/hv_netvsc/4.md), [hv\_storvsc(4)](/hv_storvsc/4.md), [hv\_utils(4)](/hv_utils/4.md), [hv\_vmbus(4)](/hv_vmbus/4.md)

## HISTORY

Support for **hv\_ata\_pci\_disengage** first appeared in FreeBSD 10.0. The driver was developed through a joint effort between Citrix Incorporated, Microsoft Corporation, and Network Appliance Incorporated.

## AUTHORS

FreeBSD support for **hv\_ata\_pci\_disengage** was first added by Microsoft BSD Integration Services Team ⟨*bsdic@microsoft.com*⟩.