[PATCH] uClinux bits for /dev/zero

uClinux ports can't use mmu tricks for reading /dev/zero due to the
lack of one.  similarly it can't mmap /dev/zero.

diff --git a/drivers/char/mem.c b/drivers/char/mem.c
index 129bce3a0d73820b235499c85f19fa22008dbad6..c1ca48f798e0d092df2f98936a7c2d534b411c5c 100644 (file)
--- a/drivers/char/mem.c
+++ b/drivers/char/mem.c
@@ -377,6 +377,7 @@ static ssize_t write_null(struct file * file, const char * buf,
        return count;
 }
 
+#ifdef CONFIG_MMU
 /*
  * For fun, we are using the MMU for this.
  */
@@ -476,6 +477,29 @@ static int mmap_zero(struct file * file, struct vm_area_struct * vma)
                return -EAGAIN;
        return 0;
 }
+#else /* CONFIG_MMU */
+static ssize_t read_zero(struct file * file, char * buf, 
+                        size_t count, loff_t *ppos)
+{
+       unsigned long left;
+
+       if (!count)
+               return 0;
+
+       for (left = count; left > 0; left--, buf++) {
+               if (put_user(0, buf))
+                       return -EFAULT;
+               cond_resched();
+       }
+
+       return count;
+}
+
+static int mmap_zero(struct file * file, struct vm_area_struct * vma)
+{
+       return -ENOSYS;
+}
+#endif /* CONFIG_MMU */
 
 static ssize_t write_full(struct file * file, const char * buf,
                          size_t count, loff_t *ppos)