Rework tiny-x vesa driver for shadowing and multiple screen support. Allow

    enable to fail and avoid crashing

hw/kdrive/src/kshadow.c

+/*
+ * $Id$
+ *
+ * Copyright © 1999 Keith Packard
+ *
+ * Permission to use, copy, modify, distribute, and sell this software and its
+ * documentation for any purpose is hereby granted without fee, provided that
+ * the above copyright notice appear in all copies and that both that
+ * copyright notice and this permission notice appear in supporting
+ * documentation, and that the name of Keith Packard not be used in
+ * advertising or publicity pertaining to distribution of the software without
+ * specific, written prior permission.  Keith Packard makes no
+ * representations about the suitability of this software for any purpose.  It
+ * is provided "as is" without express or implied warranty.
+ *
+ * KEITH PACKARD DISCLAIMS ALL WARRANTIES WITH REGARD TO THIS SOFTWARE,
+ * INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS, IN NO
+ * EVENT SHALL KEITH PACKARD BE LIABLE FOR ANY SPECIAL, INDIRECT OR
+ * CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE,
+ * DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER
+ * TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+ * PERFORMANCE OF THIS SOFTWARE.
+ */
+
+#include "kdrive.h"
+
+Bool
+KdShadowScreenInit (KdScreenInfo *screen)
+{
+    void    *buf;
+
+    buf = shadowAlloc (screen->width, screen->height, screen->fb[0].bitsPerPixel);
+    screen->fb[0].frameBuffer = buf;
+    screen->fb[0].byteStride = BitmapBytePad (screen->width * screen->fb[0].bitsPerPixel);
+    screen->fb[0].pixelStride = screen->fb[0].byteStride * 8 / screen->fb[0].bitsPerPixel;
+    screen->dumb = TRUE;
+    return TRUE;
+}
+
+Bool
+KdShadowInitScreen (ScreenPtr pScreen, ShadowUpdateProc update, ShadowWindowProc window)
+{
+    KdScreenPriv(pScreen);
+
+    return shadowInit (pScreen, update, window);
+}