Verify ebda segment looks sane before using during resume.
diff --git a/src/post.c b/src/post.c
index a642e18..97fe6ac 100644
--- a/src/post.c
+++ b/src/post.c
@@ -76,9 +76,9 @@
     struct bios_data_area_s *bda = MAKE_FLATPTR(SEG_BDA, 0);
     memset(bda, 0, sizeof(*bda));
 
-    int esize = DIV_ROUND_UP(sizeof(struct extended_bios_data_area_s), 1024);
+    int esize = EBDA_SIZE_START;
     SET_BDA(mem_size_kb, 640 - esize);
-    u16 eseg = FLATPTR_TO_SEG((640 - esize) * 1024);
+    u16 eseg = EBDA_SEGMENT_START;
     SET_BDA(ebda_seg, eseg);
 
     struct extended_bios_data_area_s *ebda = get_ebda_ptr();