ACPI mediated Hotplug?

[Krishna Yenduri]

Hi Folks,

 I have a AWS instance (m4.large) running FreeBSD 11.0-STABLE-amd64-2017-04-20.
 The system came up with a primary interface ixv0. Per pciconf -

 ixv0 at pci0:0:3:0:       class=0x020000 card=0x00000000 chip=0x10ed8086 rev=0x01 hdr=0x00
    vendor     = 'Intel Corporation'
    device     = '82599 Ethernet Controller Virtual Function'
    class      = network
    subclass   = ethernet


 I attached another network interface while the system is up. But, it does
 not show up in the pciconf -l output. Doing
        # devctl rescan pci0
 causes it to appear.

 I want to make the interface appear automatically rather
 than having to run the devctl command. BTW, this works on Linux.
 Is there a way to use the ACPI framework in FreeBSD so
 that the Hotplug happens automatically?

 DTracing shows that adding a new interface triggers calls to
 AcpiEvSciXruptHandler and AcpiEvAsynchExecuteGpeMethod.
 Is it safe to add a hook in to pci_rescan_method() from these
 routines? Any pointers to the ACPI<->FreeBSD kernel interface
 are much appreciated.

Thanks,
-Krishna