Re: How to look up ACPI device node from DXE driver

[Evgeny Yakovlev <insoreiges@gmail.com>]

Thanks Laszlo! EFI_ACPI_SDT_PROTOCOL is indeed helpful.

2017-05-18 13:59 GMT+03:00 Laszlo Ersek <lersek@redhat.com>:

> On 05/16/17 14:55, Evgeny Yakovlev wrote:
> > I am writing a DXE driver for a paravirtualized HyperV storage device for
> > OvmfPkg. Host hypervisor exposes the presence of this device through ACPI
> > device node in DSDT. Specific AML path itself may be different from host
> to
> > host but device UID is always a string: "VMBus".
> >
> > I was hoping to be able to walk DSDT table in my DXE driver to locate
> this
> > device node and start publishing necessary protocols, but I am having
> > trouble figuring out how to do this, i.e. are there any support libraries
> > or protocols to traverse ACPI tables or how do I have to do that
> manually.
> > Will be glad for any advice, thanks.
>
> This is one of the goals that EFI_ACPI_SDT_PROTOCOL serves.
>
> The protocol is specified in Volume 5 of the PI spec.
>
> In edk2, the protocol is produced by
>
>   MdeModulePkg/Universal/Acpi/AcpiTableDxe
>
> when the
>
>   gEfiMdeModulePkgTokenSpaceGuid.PcdInstallAcpiSdtProtocol
>
> Feature PCD is set to TRUE.
>
> I think there are a handful (?) of protocol consumers in edk2 as well,
> for example in
>
>   QuarkPlatformPkg/Acpi/Dxe/AcpiPlatform/
>
> Thanks,
> Laszlo
>