stubdom: use PVFB so as to e.g. permit SDL display

This adds support in ioemu for PVFB frontend as stubdomain display.
This permits for instance to use SDL in dom0 to perform the eventual
display.

Signed-off-by: Samuel Thibault <samuel.thibault@eu.citrix.com>

1 files changed, 4 insertions, 8 deletions

diff --git a/extras/mini-os/fbfront.c b/extras/mini-os/fbfront.c
index bbe49b92a5..4f5041ab69 100644
--- a/extras/mini-os/fbfront.c
+++ b/extras/mini-os/fbfront.c
@@ -31,13 +31,6 @@ struct kbdfront_dev {
     char *nodename;
     char *backend;
 
-    char *data;
-    int width;
-    int height;
-    int depth;
-    int line_length;
-    int mem_length;
-
 #ifdef HAVE_LIBC
     int fd;
 #endif
@@ -316,7 +309,10 @@ struct fbfront_dev *init_fbfront(char *nodename, void *data, int width, int heig
     for (i = 0; mapped < mem_length && i < max_pd; i++) {
         unsigned long *pd = (unsigned long *) alloc_page();
         for (j = 0; mapped < mem_length && j < PAGE_SIZE / sizeof(unsigned long); j++) {
-            pd[j] = virt_to_mfn((unsigned long) data + mapped);
+            /* Trigger CoW */
+            * ((char *)data + mapped) = 0;
+            barrier();
+            pd[j] = virtual_to_mfn((unsigned long) data + mapped);
             mapped += PAGE_SIZE;
         }
         for ( ; j < PAGE_SIZE / sizeof(unsigned long); j++)