--- 2.3.47/ipc/shm.c	Wed Mar  1 10:33:26 2000
+++ make48/ipc/shm.c	Wed Mar  1 12:54:49 2000
@@ -11,6 +11,7 @@
  * HIGHMEM support, Ingo Molnar <mingo@redhat.com>
  * avoid vmalloc and make shmmax, shmall, shmmni sysctl'able,
  *                         Christoph Rohland <hans-christoph.rohland@sap.com>
+ * Shared /dev/zero support, Kanoj Sarcar <kanoj@sgi.com>
  */
 
 #include <linux/config.h>
@@ -1100,3 +1101,24 @@
 	return len;
 }
 #endif
+
+int map_zero_setup(struct vm_area_struct *vma)
+{
+        int shmid;
+	struct shmid_kernel *shp;
+
+	down(&shm_ids.sem);
+	shmid = newseg(IPC_PRIVATE, S_IRWXUGO, vma->vm_end - vma->vm_start);
+        up(&shm_ids.sem);
+        if (shmid < 0)
+                return shmid;
+
+        if (!(shp = shm_lock (shmid)))
+                BUG();
+        shp->shm_perm.mode |= SHM_DEST;
+        shm_unlock (shmid);
+	vma->vm_private_data = shp;
+	vma->vm_ops = &shm_vm_ops;
+	shm_open (vma);
+	return 0;
+}