1 files changed, 83 insertions, 0 deletions
diff --git a/OvmfPkg/PlatformHasAcpiDtDxe/PlatformHasAcpiDtDxe.c b/OvmfPkg/PlatformHasAcpiDtDxe/PlatformHasAcpiDtDxe.c
new file mode 100644
index 0000000000..952d9bfc1f
--- /dev/null
+++ b/OvmfPkg/PlatformHasAcpiDtDxe/PlatformHasAcpiDtDxe.c
@@ -0,0 +1,83 @@
+/** @file
+  Decide whether the firmware should expose an ACPI- and/or a Device Tree-based
+  hardware description to the operating system.
+
+  Copyright (c) 2017, Red Hat, Inc.
+
+  SPDX-License-Identifier: BSD-2-Clause-Patent
+**/
+
+#include <Guid/PlatformHasAcpi.h>
+#include <Guid/PlatformHasDeviceTree.h>
+#include <Library/BaseLib.h>
+#include <Library/DebugLib.h>
+#include <Library/PcdLib.h>
+#include <Library/QemuFwCfgLib.h>
+#include <Library/UefiBootServicesTableLib.h>
+
+EFI_STATUS
+EFIAPI
+PlatformHasAcpiDt (
+  IN EFI_HANDLE        ImageHandle,
+  IN EFI_SYSTEM_TABLE  *SystemTable
+  )
+{
+  EFI_STATUS            Status;
+  FIRMWARE_CONFIG_ITEM  FwCfgItem;
+  UINTN                 FwCfgSize;
+
+  //
+  // If we fail to install any of the necessary protocols below, the OS will be
+  // unbootable anyway (due to lacking hardware description), so tolerate no
+  // errors here.
+  //
+  if ((MAX_UINTN == MAX_UINT64) &&
+      !PcdGetBool (PcdForceNoAcpi) &&
+      !EFI_ERROR (
+         QemuFwCfgFindFile (
+           "etc/table-loader",
+           &FwCfgItem,
+           &FwCfgSize
+           )
+         ))
+  {
+    //
+    // Only make ACPI available on 64-bit systems, and only if QEMU generates
+    // (a subset of) the ACPI tables.
+    //
+    Status = gBS->InstallProtocolInterface (
+                    &ImageHandle,
+                    &gEdkiiPlatformHasAcpiGuid,
+                    EFI_NATIVE_INTERFACE,
+                    NULL
+                    );
+    if (EFI_ERROR (Status)) {
+      goto Failed;
+    }
+
+    return Status;
+  }
+
+  //
+  // Expose the Device Tree otherwise.
+  //
+  Status = gBS->InstallProtocolInterface (
+                  &ImageHandle,
+                  &gEdkiiPlatformHasDeviceTreeGuid,
+                  EFI_NATIVE_INTERFACE,
+                  NULL
+                  );
+  if (EFI_ERROR (Status)) {
+    goto Failed;
+  }
+
+  return Status;
+
+Failed:
+  ASSERT_EFI_ERROR (Status);
+  CpuDeadLoop ();
+  //
+  // Keep compilers happy.
+  //
+  return Status;
+}