xen, vga: add API for registering the framebuffer

Xen currently uses the name of a memory region to determine whether it
is the framebuffer.  Replace with an explicit API.

Signed-off-by: Avi Kivity <avi@redhat.com>

hw/vga.c

@@ -28,6 +28,7 @@
 #include "vga_int.h"
 #include "pixel_ops.h"
 #include "qemu-timer.h"
+#include "xen.h"
 
 //#define DEBUG_VGA
 //#define DEBUG_VGA_MEM
@@ -2222,6 +2223,7 @@ void vga_common_init(VGACommonState *s, int vga_ram_size)
     s->is_vbe_vmstate = 0;
 #endif
     memory_region_init_ram(&s->vram, NULL, "vga.vram", vga_ram_size);
+    xen_register_framebuffer(&s->vram);
     s->vram_ptr = memory_region_get_ram_ptr(&s->vram);
     s->vram_size = vga_ram_size;
     s->get_bpp = vga_get_bpp;

hw/xen.h

@@ -49,6 +49,9 @@ void xen_ram_alloc(ram_addr_t ram_addr, ram_addr_t size,
                    struct MemoryRegion *mr);
 #endif
 
+struct MemoryRegion;
+void xen_register_framebuffer(struct MemoryRegion *mr);
+
 #if defined(CONFIG_XEN) && CONFIG_XEN_CTRL_INTERFACE_VERSION < 400
 #  define HVM_MAX_VCPUS 32
 #endif

xen-all.c

@@ -33,6 +33,7 @@
 #endif
 
 static MemoryRegion ram_memory, ram_640k, ram_lo, ram_hi;
+static MemoryRegion *framebuffer;
 
 /* Compatibility with older version */
 #if __XEN_LATEST_INTERFACE_VERSION__ < 0x0003020a
@@ -982,3 +983,8 @@ void destroy_hvm_domain(void)
         xc_interface_close(xc_handle);
     }
 }
+
+void xen_register_framebuffer(MemoryRegion *mr)
+{
+    framebuffer = mr;
+}

xen-stub.c

@@ -44,3 +44,7 @@ int xen_init(void)
 {
     return -ENOSYS;
 }
+
+void xen_register_framebuffer(MemoryRegion *mr)
+{
+}