From ec88061ec82d3ebf6a83d562d17583b70e32ce13 Mon Sep 17 00:00:00 2001
From: Laszlo Ersek <lersek@redhat.com>
Date: Mon, 3 Mar 2014 08:41:08 +0000
Subject: [PATCH] OvmfPkg: QemuVideoDxe: filter BOCHS modes vs. available frame
 buffer size

In the next patch we'll add many new BOCHS modes, some of which require
large frame buffers.

The size of the QXL VGA compatibility framebuffer can be changed with the

  -global qxl-vga.vgamem_mb=$NUM_MB

QEMU option.

If $NUM_MB would exceed 32, then the following two QEMU options are
necessary instead:

  -global qxl-vga.vgamem_mb=$NUM_MB         \
  -global qxl-vga.ram_size_mb=$((NUM_MB*2))

because the compatibility framebuffer can't cover more than half of PCI
BAR #0. The latter defaults to 64MB in size, and is controlled by
"ram_size_mb".

Contributed-under: TianoCore Contribution Agreement 1.0
Signed-off-by: Laszlo Ersek <lersek@redhat.com>
Reviewed-by: Jordan Justen <jordan.l.justen@intel.com>

git-svn-id: https://svn.code.sf.net/p/edk2/code/trunk/edk2@15288 6f19259b-4bc3-4df7-8a09-765794883524
---
 OvmfPkg/QemuVideoDxe/Initialize.c | 52 ++++++++++++++++++++-----------
 1 file changed, 34 insertions(+), 18 deletions(-)

diff --git a/OvmfPkg/QemuVideoDxe/Initialize.c b/OvmfPkg/QemuVideoDxe/Initialize.c
index af3b6af47c..80e9b3a936 100644
--- a/OvmfPkg/QemuVideoDxe/Initialize.c
+++ b/OvmfPkg/QemuVideoDxe/Initialize.c
@@ -200,7 +200,7 @@ QemuVideoCirrusModeSetup (
     ModeData ++ ;
     VideoMode ++;
   }
-  Private->MaxMode = QEMU_VIDEO_CIRRUS_MODE_COUNT;
+  Private->MaxMode = ModeData - Private->ModeData;
 
   return EFI_SUCCESS;
 }
@@ -222,10 +222,19 @@ QemuVideoBochsModeSetup (
   QEMU_VIDEO_PRIVATE_DATA  *Private
   )
 {
+  UINT32                                 AvailableFbSize;
   UINT32                                 Index;
   QEMU_VIDEO_MODE_DATA                   *ModeData;
   QEMU_VIDEO_BOCHS_MODES                 *VideoMode;
 
+  //
+  // fetch available framebuffer size
+  //
+  AvailableFbSize  = BochsRead (Private, VBE_DISPI_INDEX_VIDEO_MEMORY_64K);
+  AvailableFbSize *= SIZE_64KB;
+  DEBUG ((EFI_D_VERBOSE, "%a: AvailableFbSize=0x%x\n", __FUNCTION__,
+    AvailableFbSize));
+
   //
   // Setup Video Modes
   //
@@ -238,25 +247,32 @@ QemuVideoBochsModeSetup (
   ModeData = Private->ModeData;
   VideoMode = &QemuVideoBochsModes[0];
   for (Index = 0; Index < QEMU_VIDEO_BOCHS_MODE_COUNT; Index ++) {
-    ModeData->InternalModeIndex = Index;
-    ModeData->HorizontalResolution          = VideoMode->Width;
-    ModeData->VerticalResolution            = VideoMode->Height;
-    ModeData->ColorDepth                    = VideoMode->ColorDepth;
-    ModeData->RefreshRate                   = 60;
-    DEBUG ((EFI_D_INFO,
-      "Adding Mode %d as Bochs Internal Mode %d: %dx%d, %d-bit, %d Hz\n",
-      (INT32) (ModeData - Private->ModeData),
-      ModeData->InternalModeIndex,
-      ModeData->HorizontalResolution,
-      ModeData->VerticalResolution,
-      ModeData->ColorDepth,
-      ModeData->RefreshRate
-      ));
-
-    ModeData ++ ;
+    UINTN RequiredFbSize;
+
+    ASSERT (VideoMode->ColorDepth % 8 == 0);
+    RequiredFbSize = (UINTN) VideoMode->Width * VideoMode->Height *
+                     (VideoMode->ColorDepth / 8);
+    if (RequiredFbSize <= AvailableFbSize) {
+      ModeData->InternalModeIndex    = Index;
+      ModeData->HorizontalResolution = VideoMode->Width;
+      ModeData->VerticalResolution   = VideoMode->Height;
+      ModeData->ColorDepth           = VideoMode->ColorDepth;
+      ModeData->RefreshRate          = 60;
+      DEBUG ((EFI_D_INFO,
+        "Adding Mode %d as Bochs Internal Mode %d: %dx%d, %d-bit, %d Hz\n",
+        (INT32) (ModeData - Private->ModeData),
+        ModeData->InternalModeIndex,
+        ModeData->HorizontalResolution,
+        ModeData->VerticalResolution,
+        ModeData->ColorDepth,
+        ModeData->RefreshRate
+        ));
+
+      ModeData ++ ;
+    }
     VideoMode ++;
   }
-  Private->MaxMode = QEMU_VIDEO_BOCHS_MODE_COUNT;
+  Private->MaxMode = ModeData - Private->ModeData;
 
   return EFI_SUCCESS;
 }
-- 
2.39.2