How to disable ata driver on Hyper-V

[Scott Long]

Hi,

There’s no direct way to disable a specific driver or specific instance of a driver.  There are ways to disable a particular PCI function, but I’m not sure if that’s what you want.  Are you looking to override the default ata driver with your own custom driver?  The way to do that is have your custom driver provide a higher priority return code from its dev_probe routine.  The way this works is that positive return codes indicate an error.  Negative return codes indicate a priority, with the numbers closer to zero being a higher priority.  Zero is the highest priority, but should be used only with great care.  The priority for the default ahci driver is BUS_PROBE_DEFAULT, which resolves to (-20).  You might consider using BUS_PROBE_VENDOR, which resolves to (-10).  By having your driver look at the PCI bus:device:function tuple, you can selectively override the default driver for specific hardware.

Scott

> On Aug 17, 2016, at 2:49 AM, Hongjiang Zhang via freebsd-scsi <freebsd-scsi at freebsd.org> wrote:
> 
> Hi all,
> 
> I'm want to disable the default ata driver for FreeBSD on Hyper-V. How to do that?
> 
> Thanks
> Hongjiang Zhang
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