Changeset 82107 in vbox

Timestamp:

Nov 22, 2019 6:32:44 PM (5 years ago)

Author:

vboxsync

svn:sync-xref-src-repo-rev:

134916

Message:

EFI/Firmware/CpuGdt.c: Revert previous patch and add explanation why AllocateReservedPool() should be used instead of AllocateRuntimePool()

File:

• trunk/src/VBox/Devices/EFI/Firmware/UefiCpuPkg/CpuDxe/CpuGdt.c (modified) (1 diff)

trunk/src/VBox/Devices/EFI/Firmware/UefiCpuPkg/CpuDxe/CpuGdt.c

@@ -128 +128 @@
   IA32_DESCRIPTOR gdtPtr;
 
-#ifndef VBOX
   //
   // Allocate Runtime Data for the GDT
   //
+#ifndef VBOX
   gdt = AllocateRuntimePool (sizeof (GdtTemplate) + 8);
+#else
+  /*
+   * Apples bootloader boot.efi for at least OS X Tiger, Leopard and Snow Leopard
+   * relocates runtime regions which doesn't make sense for the GDT as the GDTR is not
+   * updated and would point to invalid memory. Allocate the memory as reserved to hopefully
+   * keep the bootloaders hands off of it, see also OvmfPkg/PlatformPei/Platform.c
+   * (search for PeiServicesAllocatePages()) for a more detailed explanation of a
+   * related bug in Apples bootloader.
+   */
+  gdt = AllocateReservedPool (sizeof (GdtTemplate) + 8);
+#endif
   ASSERT (gdt != NULL);
   gdt = ALIGN_POINTER (gdt, 8);
-#else
-   /*
-    * With previous versions of the EDK2 changing AllocateRuntimePool to AllocateReservedPool
-    * was enough to get earlier mac OS versions (Tiger up until at least Snow Leopard) not overwriting the GDT
-    * when freeing not required EFI memory ranges anymore.
-    * With the current version however the memory map (memmap command in EFI shell) returned to boot.efi
-    * will have the Runtime flag always cleared no matter what. boot.efi overwrites the memory and
-    * the VM triple faults because of the invalid GDT.
-    * Using the AllocatePages() method with EfiRuntimeServicesData works around that and the GDT memory
-    * has the proper Runtime flag set so boot.efi will leave it alone.
-    */
-  EFI_STATUS Status;
-  EFI_PHYSICAL_ADDRESS PhysicalAddress = SIZE_4GB - 1;
-  Status = gBS->AllocatePages(AllocateMaxAddress,
-                              EfiRuntimeServicesData,
-                              1,
-                              &PhysicalAddress);
-  ASSERT(!EFI_ERROR(Status));
-  gdt = ALIGN_POINTER ((void *)(UINTN)PhysicalAddress, 8);
-#endif
 
   //