diff --git a/common/hw-gfx-gma-config_helpers.ads b/common/hw-gfx-gma-config_helpers.ads
index e684f22..1dc2390 100644
--- a/common/hw-gfx-gma-config_helpers.ads
+++ b/common/hw-gfx-gma-config_helpers.ads
@@ -50,6 +50,6 @@
             Rotated_Width (FB) <= Port_Cfg.Mode.H_Visible and
             Rotated_Height (FB) <= Port_Cfg.Mode.V_Visible and
             (FB.Offset = VGA_PLANE_FRAMEBUFFER_OFFSET or
-             FB.Height <= FB.V_Stride));
+             FB.Height + FB.Start_Y <= FB.V_Stride));
 
 end HW.GFX.GMA.Config_Helpers;
diff --git a/common/hw-gfx-gma-pipe_setup.adb b/common/hw-gfx-gma-pipe_setup.adb
index e2d2567..5c6df37 100644
--- a/common/hw-gfx-gma-pipe_setup.adb
+++ b/common/hw-gfx-gma-pipe_setup.adb
@@ -162,7 +162,7 @@
               (Registers.Register_State,
                Controller,
                FB)),
-      Pre => FB.Height <= FB.V_Stride
+      Pre => FB.Height + FB.Start_Y <= FB.V_Stride
    is
       -- FIXME: setup correct format, based on framebuffer RGB format
       Format : constant Word32 := 6 * 2 ** 26;
@@ -177,11 +177,13 @@
             Height : constant Pos16 := Rotated_Height (FB);
          begin
             if Rotation_90 (FB) then
-               Stride            := Word32 (FB_Pitch (FB.V_Stride, FB));
-               Offset            := Word32 (FB.V_Stride - FB.Height);
+               Stride   := Word32 (FB_Pitch (FB.V_Stride, FB));
+               Offset   := Shift_Left (Word32 (FB.Start_X), 16) or
+                           Word32 (FB.V_Stride - FB.Height - FB.Start_Y);
             else
-               Stride            := Word32 (FB_Pitch (FB.Stride, FB));
-               Offset            := 0;
+               Stride   := Word32 (FB_Pitch (FB.Stride, FB));
+               Offset   := Shift_Left (Word32 (FB.Start_Y), 16) or
+                           Word32 (FB.Start_X);
             end if;
             Registers.Write
               (Register    => Controller.PLANE_CTL,
@@ -211,9 +213,17 @@
            (Controller.DSPSTRIDE, Word32 (Pixel_To_Bytes (FB.Stride, FB)));
          Registers.Write (Controller.DSPSURF, FB.Offset and 16#ffff_f000#);
          if Config.Has_DSP_Linoff then
-            Registers.Write (Controller.DSPLINOFF, 0);
+            Registers.Write
+              (Register => Controller.DSPLINOFF,
+               Value    => Word32 (Pixel_To_Bytes
+                             (FB.Start_Y * FB.Stride + FB.Start_X, FB)));
+            Registers.Write (Controller.DSPTILEOFF, 0);
+         else
+            Registers.Write
+              (Register => Controller.DSPTILEOFF,
+               Value    => Shift_Left (Word32 (FB.Start_Y), 16) or
+                           Word32 (FB.Start_X));
          end if;
-         Registers.Write (Controller.DSPTILEOFF, 0);
       end if;
    end Setup_Hires_Plane;
 
@@ -237,7 +247,7 @@
                (Framebuffer)),
       Pre =>
          Framebuffer.Offset = VGA_PLANE_FRAMEBUFFER_OFFSET or
-         Framebuffer.Height <= Framebuffer.V_Stride
+         Framebuffer.Height + Framebuffer.Start_Y <= Framebuffer.V_Stride
    is
       use type Word8;
 
diff --git a/common/hw-gfx-gma-pipe_setup.ads b/common/hw-gfx-gma-pipe_setup.ads
index 35d9e87..3ef5dcf 100644
--- a/common/hw-gfx-gma-pipe_setup.ads
+++ b/common/hw-gfx-gma-pipe_setup.ads
@@ -28,7 +28,7 @@
          Rotated_Width (Framebuffer) <= Port_Cfg.Mode.H_Visible and
          Rotated_Height (Framebuffer) <= Port_Cfg.Mode.V_Visible and
          (Framebuffer.Offset = VGA_PLANE_FRAMEBUFFER_OFFSET or
-          Framebuffer.Height <= Framebuffer.V_Stride);
+          Framebuffer.Height + Framebuffer.Start_Y <= Framebuffer.V_Stride);
 
    procedure Off (Pipe : Pipe_Index);
 
diff --git a/common/hw-gfx-gma.adb b/common/hw-gfx-gma.adb
index 6f4594b..0e2c835 100644
--- a/common/hw-gfx-gma.adb
+++ b/common/hw-gfx-gma.adb
@@ -723,6 +723,21 @@
         (Primary     => "Primary  ",
          Secondary   => "Secondary",
          Tertiary    => "Tertiary ");
+
+      subtype Tiling_Name is String (1 .. 7);
+      type Tiling_Name_Array is array (Tiling_Type) of Tiling_Name;
+      Tilings : constant Tiling_Name_Array :=
+        (Linear   => "Linear ",
+         X_Tiled  => "X_Tiled",
+         Y_Tiled  => "Y_Tiled");
+
+      subtype Rotation_Name is String (1 .. 11);
+      type Rotation_Name_Array is array (Rotation_Type) of Rotation_Name;
+      Rotations : constant Rotation_Name_Array :=
+        (No_Rotation => "No_Rotation",
+         Rotated_90  => "Rotated_90 ",
+         Rotated_180 => "Rotated_180",
+         Rotated_270 => "Rotated_270");
    begin
       Debug.New_Line;
       Debug.Put_Line ("CONFIG =>");
@@ -736,15 +751,28 @@
          Debug.Put_Line
            ("     (Port => " & Port_Names (Configs (Pipe).Port) & ",");
          Debug.Put_Line ("      Framebuffer =>");
-         Debug.Put ("        (Width  => ");
+         Debug.Put ("        (Width     => ");
          Debug.Put_Int32 (Configs (Pipe).Framebuffer.Width);
          Debug.Put_Line (",");
-         Debug.Put ("         Height => ");
+         Debug.Put ("         Height    => ");
          Debug.Put_Int32 (Configs (Pipe).Framebuffer.Height);
          Debug.Put_Line (",");
-         Debug.Put ("         Stride => ");
+         Debug.Put ("         Start_X   => ");
+         Debug.Put_Int32 (Configs (Pipe).Framebuffer.Start_X);
+         Debug.Put_Line (",");
+         Debug.Put ("         Start_Y   => ");
+         Debug.Put_Int32 (Configs (Pipe).Framebuffer.Start_Y);
+         Debug.Put_Line (",");
+         Debug.Put ("         Stride    => ");
          Debug.Put_Int32 (Configs (Pipe).Framebuffer.Stride);
          Debug.Put_Line (",");
+         Debug.Put ("         V_Stride  => ");
+         Debug.Put_Int32 (Configs (Pipe).Framebuffer.V_Stride);
+         Debug.Put_Line (",");
+         Debug.Put ("         Tiling    => ");
+         Debug.Put_Line (Tilings (Configs (Pipe).Framebuffer.Tiling) & ",");
+         Debug.Put ("         Rotation  => ");
+         Debug.Put_Line (Rotations (Configs (Pipe).Framebuffer.Rotation) & ",");
          Debug.Put ("         Offset => ");
          Debug.Put_Word32 (Configs (Pipe).Framebuffer.Offset);
          Debug.Put_Line (",");
diff --git a/common/hw-gfx-gma.ads b/common/hw-gfx-gma.ads
index 77def8e..c35c687 100644
--- a/common/hw-gfx-gma.ads
+++ b/common/hw-gfx-gma.ads
@@ -177,14 +177,14 @@
    Tile_Rows : constant array (Tiling_Type) of Pos32 :=
      (Linear => 1, X_Tiled => 8, Y_Tiled => 32);
 
-   function FB_Pitch (Px : Pixel_Type; FB : Framebuffer_Type) return Natural is
-     (Natural (Div_Round_Up
-        (Pixel_To_Bytes (Px, FB), Tile_Width (FB.Tiling) * 4)));
+   function FB_Pitch (Px : Pos_Pixel_Type; FB : Framebuffer_Type) return Natural
+      is (Natural (Div_Round_Up
+           (Pixel_To_Bytes (Px, FB), Tile_Width (FB.Tiling) * 4)));
 
    function Valid_Stride (FB : Framebuffer_Type) return Boolean is
-     (FB.Width <= FB.Stride and
+     (FB.Width + FB.Start_X <= FB.Stride and
       Pixel_To_Bytes (FB.Stride, FB) mod (Tile_Width (FB.Tiling) * 4) = 0 and
-      FB.Height <= FB.V_Stride and
+      FB.Height + FB.Start_Y <= FB.V_Stride and
       FB.V_Stride mod Tile_Rows (FB.Tiling) = 0);
 
 end HW.GFX.GMA;
diff --git a/common/hw-gfx.ads b/common/hw-gfx.ads
index 5d8ae59..1ab2518 100644
--- a/common/hw-gfx.ads
+++ b/common/hw-gfx.ads
@@ -21,11 +21,13 @@
 package HW.GFX is
 
    -- such that the count of pixels in any framebuffer may fit
-   subtype Pixel_Type is Pos32 range 1 .. 8192 * 8192;
+   subtype Pixel_Type is Int32 range 0 .. 8192 * 8192;
+   subtype Pos_Pixel_Type is Pixel_Type range 1 .. Pixel_Type'Last;
 
    -- Allow same range for width and height (for rotated framebuffers)
    subtype Width_Type  is Pos32 range 1 .. 8192;
    subtype Height_Type is Pos32 range 1 .. 8192;
+   subtype Pos_Type    is Int32 range 0 .. 4095;
 
    Auto_BPC : constant := 5;
    subtype BPC_Type    is Int64 range Auto_BPC .. 16;
@@ -39,6 +41,8 @@
    record
       Width    : Width_Type;
       Height   : Height_Type;
+      Start_X  : Pos_Type;
+      Start_Y  : Pos_Type;
       BPC      : BPC_Type;
       Stride   : Width_Type;
       V_Stride : Height_Type;
@@ -56,13 +60,15 @@
      (if Rotation_90 (FB) then Pos16 (FB.Width) else Pos16 (FB.Height));
 
    function Pixel_To_Bytes (Pixel : Pixel_Type; FB : Framebuffer_Type)
-      return Pos32 is (Pixel * Pos32 (FB.BPC) / (8 / 4));
+      return Int32 is (Pixel * Pos32 (FB.BPC) / (8 / 4));
    function FB_Size (FB : Framebuffer_Type) return Pos32 is
      (Pixel_To_Bytes (FB.Stride * FB.V_Stride, FB));
 
    Default_FB : constant Framebuffer_Type := Framebuffer_Type'
      (Width    => 1,
       Height   => 1,
+      Start_X  => 0,
+      Start_Y  => 0,
       BPC      => 8,
       Stride   => 1,
       V_Stride => 1,
diff --git a/gfxtest/hw-gfx-gma-gfx_test.adb b/gfxtest/hw-gfx-gma-gfx_test.adb
index cb09c63..833240f 100644
--- a/gfxtest/hw-gfx-gma-gfx_test.adb
+++ b/gfxtest/hw-gfx-gma-gfx_test.adb
@@ -14,6 +14,9 @@
 is
    pragma Disable_Atomic_Synchronization;
 
+   Start_X : constant := 0;
+   Start_Y : constant := 0;
+
    package Dev is new PCI.Dev (PCI.Address'(0, 2, 0));
 
    type GTT_PTE_Type is mod 2 ** (Config.GTT_PTE_Size * 8);
@@ -105,6 +108,12 @@
       end loop;
    end Restore_Screen;
 
+   function Drawing_Width (FB : Framebuffer_Type) return Natural is
+     (Natural (FB.Width + 2 * Start_X));
+
+   function Drawing_Height (FB : Framebuffer_Type) return Natural is
+     (Natural (FB.Height + 2 * Start_Y));
+
    function Corner_Fill
      (X, Y  : Natural;
       FB    : Framebuffer_Type;
@@ -112,9 +121,9 @@
       return Pixel_Type
    is
       Xrel : constant Integer :=
-        (if X < 32 then X else X - (Natural (FB.Width) - 32));
+        (if X < 32 then X else X - (Drawing_Width (FB) - 32));
       Yrel : constant Integer :=
-        (if Y < 32 then Y else Y - (Natural (FB.Height) - 32));
+        (if Y < 32 then Y else Y - (Drawing_Height (FB) - 32));
 
       function Color (Idx : Natural) return Pixel_Type is
         (case (Idx + Pipe_Index'Pos (Pipe)) mod 4 is
@@ -138,8 +147,8 @@
    is
       use type HW.Byte;
 
-      Xp : constant Natural := X * 256 / Natural (Framebuffer.Width);
-      Yp : constant Natural := Y * 256 / Natural (Framebuffer.Height);
+      Xp : constant Natural := X * 256 / Drawing_Width (Framebuffer);
+      Yp : constant Natural := Y * 256 / Drawing_Height (Framebuffer);
       Xn : constant Natural := 255 - Xp;
       Yn : constant Natural := 255 - Yp;
 
@@ -166,22 +175,22 @@
 
       function Top_Test (X, Y : Natural) return Boolean
       is
-         C     : constant Natural := Natural (Framebuffer.Width) / 2;
-         S_Y   : constant Natural := 3 * Y / 2;
+         C     : constant Natural := Drawing_Width (Framebuffer) / 2;
+         S_Y   : constant Natural := 3 * (Y - Start_Y) / 2;
          Left  : constant Integer := X - C + S_Y;
          Right : constant Integer := X - C - S_Y;
       begin
          return
-            Y < 12 and
+            (Y - Start_Y) < 12 and
             ((-1 <= Left and Left <= 0) or
              (0 <= Right and Right <= 1));
       end Top_Test;
    begin
-      for Y in 0 .. Natural (Framebuffer.Height) - 1 loop
+      for Y in 0 .. Drawing_Height (Framebuffer) - 1 loop
          Offset := Offset_Y;
-         for X in 0 .. Natural (Framebuffer.Width) - 1 loop
-            if (X < 32 or X >= Natural (Framebuffer.Width) - 32) and
-               (Y < 32 or Y >= Natural (Framebuffer.Height) - 32)
+         for X in 0 .. Drawing_Width (Framebuffer) - 1 loop
+            if (X < 32 or X >= Drawing_Width (Framebuffer) - 32) and
+               (Y < 32 or Y >= Drawing_Height (Framebuffer) - 32)
             then
                P := Corner_Fill (X, Y, Framebuffer, Pipe);
             elsif Framebuffer.Rotation /= No_Rotation and then
@@ -206,25 +215,31 @@
       Rotation : in     Rotation_Type;
       Offset   : in out Word32)
    is
+      Width : constant Width_Type := Width_Type (Mode.H_Visible);
+      Height : constant Height_Type := Height_Type (Mode.V_Visible);
    begin
       Offset := (Offset + FB_Align - 1) and not (FB_Align - 1);
       if Rotation = Rotated_90 or Rotation = Rotated_270 then
          FB :=
-           (Width    => Width_Type (Mode.V_Visible),
-            Height   => Height_Type (Mode.H_Visible),
+           (Width    => Width_Type (Height),
+            Height   => Height_Type (Width),
+            Start_X  => Start_X,
+            Start_Y  => Start_Y,
             BPC      => 8,
-            Stride   => Div_Round_Up (Pos32 (Mode.V_Visible), 32) * 32,
-            V_Stride => Div_Round_Up (Pos32 (Mode.H_Visible), 32) * 32,
+            Stride   => Div_Round_Up (Pos32 (Height + 2 * Start_X), 32) * 32,
+            V_Stride => Div_Round_Up (Pos32 (Width + 2 * Start_Y), 32) * 32,
             Tiling   => Y_Tiled,
             Rotation => Rotation,
             Offset   => Offset + Word32 (GTT_Rotation_Offset) * GTT_Page_Size);
       else
          FB :=
-           (Width    => Width_Type (Mode.H_Visible),
-            Height   => Width_Type (Mode.V_Visible),
+           (Width    => Width,
+            Height   => Height,
+            Start_X  => Start_X,
+            Start_Y  => Start_Y,
             BPC      => 8,
-            Stride   => Div_Round_Up (Pos32 (Mode.H_Visible), 16) * 16,
-            V_Stride => Height_Type (Mode.V_Visible),
+            Stride   => Div_Round_Up (Width + 2 * Start_X, 16) * 16,
+            V_Stride => Height + 2 * Start_Y,
             Tiling   => Linear,
             Rotation => Rotation,
             Offset   => Offset);