Thanks for the answer Laszlo.
I'll thake a look on these information.
Nice to know this question helped you too.
Thanks
Rafael R. Machado
2014-01-31 Laszlo Ersek <ler...@redhat.com>:
> On 01/31/14 11:39, Rafael Machado wrote:
> > Hi everyone.
> >
> > I have a question.
> > I need to read some ACPI tables data at UEFI.
> > As far as I could check, the only defined protocols to work with acpi
> > tables at uefi are related to install and unninstall a new table, but
> > how could I do to read a table already defined by the ACPI spec ?
> > For example read the information contained at the Differentiated System
> > Description Table (DSDT).
>
> You can install and uninstall tables with EFI_ACPI_TABLE_PROTOCOL.
> See UEFI 2.4a, 19 Protocols - ACPI Protocols.
>
> Apparently, you can locate and walk tables with EFI_ACPI_SDT_PROTOCOL.
> See Platform Init Vol.5, 9 ACPI System Description Table Protocol.
>
> In edk2, the reference implementation for both of these is provided by
> MdeModulePkg/Universal/Acpi/AcpiTableDxe. EFI_ACPI_SDT_PROTOCOL is only
> installed dependent on
> "gEfiMdeModulePkgTokenSpaceGuid.PcdInstallAcpiSdtProtocol".
>
> OVMF (for example) already builds in the driver, but for now we only use
> the EFI_ACPI_TABLE_PROTOCOL that the driver provides. If you want the
> other protocol too, you likely have to set said PCD to TRUE, in
> OvmfPkg/OvmfPkg*.dsc, under [PcdsFeatureFlag].
>
> Thanks for making me investigate this a little bit, especially
> EFI_ACPI_SDT_PROTOCOL. In OvmfPkg we might want to inspect, at some
> point, the ACPI tables that QEMU exports, and EFI_ACPI_SDT_PROTOCOL
> could be handy to navigate them.
>
> Laszlo
>
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