$FreeBSD: releng/11.0/share/man/man4/hv_ata_pci_disengage.4 276259 2014-12-26 22:30:18Z bapt $ Copyright (c) 2012 Microsoft Corp. All rights reserved. Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following conditions are met: 1. Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer. 2. Redistributions in binary form must reproduce the above copyright ...
NAMEhv_ata_pci_disengage - Hyper-V ATA PCI Disengage driver
SYNOPSISTo compile this driver into the kernel, place the following lines in the system kernel configuration file:
DESCRIPTIONThe sysctl Cm net.inet.tcp.syncookies 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 (hv_storvsc4 ) 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_storvsc4. The sysctl Cm net.inet.tcp.syncookies driver avoids conflicts between the ATA driver and hv_storvsc4 by disabling the ATA driver when the Fx guest is booting.
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.