PATCH: only throw away page zero when needed

[Johan Rydberg]

Hi,

Another fix for the PowerPC port.

2003-10-01  Johan Rydberg  <address@hidden>

        * wortel.c (serve_bootstrap_requests): Only throw away page
        zero if it list as conventinal in memory descriptors.

Index: wortel.c
===================================================================
RCS file: /cvsroot/hurd/hurd-l4/wortel/wortel.c,v
retrieving revision 1.18
diff -u -p -r1.18 wortel.c
--- wortel.c    25 Sep 2003 00:29:14 -0000      1.18
+++ wortel.c    1 Oct 2003 21:15:35 -0000
@@ -398,6 +398,8 @@ start_components (void)
 static void
 serve_bootstrap_requests (void)
 {
+  int i, get_page_zero = 0;
+
   /* The size of the region that we are currently trying to allocate
      for GET_MEM requests.  If this is smaller than L4_MIN_PAGE_SIZE,
      no more memory is available.  */
@@ -411,9 +413,17 @@ serve_bootstrap_requests (void)
   hurd_task_id_t server_task = (mod_idx < mods_count)
     ? l4_version (mods[mod_idx].main_thread) : 0;
 
-  /* Allocate a single page at address 0, because we don't want to
-     bother anybody with that silly page.  */
-  sigma0_get_fpage (l4_fpage (0, l4_min_page_size ()));
+  /* If a conventinal page with address 0 exists in the memory
+     descriptors, allocate it because we don't want to bother anybody 
+     with that silly page.  */
+  for (i = 0; i < loader_get_num_memory_desc (); i++)
+    {
+      l4_memory_desc_t memdesc = loader_get_memory_desc (i);
+      if (memdesc->low == 0)
+       get_page_zero = (memdesc->type == L4_MEMDESC_CONVENTIONAL);
+    }
+  if (get_page_zero)
+    sigma0_get_fpage (l4_fpage (0, l4_min_page_size ()));
 
   do
     {