OvmfPkg/XenPlatformPei: Reserve VGA memory region, to boot Linux

Linux panic if the VGA region isn't reserved.

When Linux is booted on EFI system, it expects the memory at 0xa0000 to
_not_ be conventional memory. Otherwise a variable isn't initialised
properly and Linux panic when a virtual console/terminal is asked to be
created.

See for more detail:
https://lists.xenproject.org/archives/html/xen-devel/2019-03/msg02139.html

Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=1689
Signed-off-by: Anthony PERARD <anthony.perard@citrix.com>
Acked-by: Laszlo Ersek <lersek@redhat.com>
Message-Id: <20190813113119.14804-25-anthony.perard@citrix.com>

1 files changed, 16 insertions, 0 deletions

diff --git a/OvmfPkg/XenPlatformPei/Xen.c b/OvmfPkg/XenPlatformPei/Xen.c
index c4506def9a..c41fecdc48 100644
--- a/OvmfPkg/XenPlatformPei/Xen.c
+++ b/OvmfPkg/XenPlatformPei/Xen.c
@@ -294,6 +294,12 @@ XenPublishRamRegions (
   Status = XenGetE820Map (&E820Map, &E820EntriesCount);

   ASSERT_EFI_ERROR (Status);

 

+  AddMemoryBaseSizeHob (0, 0xA0000);

+  //

+  // Video memory + Legacy BIOS region, to allow Linux to boot.

+  //

+  AddReservedMemoryBaseSizeHob (0xA0000, BASE_1MB - 0xA0000, TRUE);

+

   LapicBase = PcdGet32 (PcdCpuLocalApicBaseAddress);

   LapicEnd = LapicBase + SIZE_1MB;

   AddIoMemoryRangeHob (LapicBase, LapicEnd);

@@ -312,6 +318,16 @@ XenPublishRamRegions (
     Base = ALIGN_VALUE (Entry->BaseAddr, (UINT64)EFI_PAGE_SIZE);

     End = (Entry->BaseAddr + Entry->Length) & ~(UINT64)EFI_PAGE_MASK;

 

+    //

+    // Ignore the first 1MB, this is handled before the loop.

+    //

+    if (Base < BASE_1MB) {

+      Base = BASE_1MB;

+    }

+    if (Base >= End) {

+      continue;

+    }

+

     switch (Entry->Type) {

     case EfiAcpiAddressRangeMemory:

       AddMemoryRangeHob (Base, End);