[POWERPC] Automatically lmb_reserve() initrd

At present, when an initrd is passed to the kernel used flat device
tree properties, the memory the initrd occupies must also be reserved
in the flat tree's reserve map, or the kernel may overwrite it.  That
makes life more complicated than it could be for the bootwrapper.

This patch makes the kernel automatically reserve the initrd's space.
That in turn requires parsing the initrd parameters earlier than they
are currently, in early_init_dt_scan_chosen() instead of
check_for_initrd().

Signed-off-by: David Gibson <dwg@au1.ibm.com>
Signed-off-by: Paul Mackerras <paulus@samba.org>

arch/powerpc/kernel/prom.c

@@ -719,6 +719,7 @@ static int __init early_init_dt_scan_chosen(unsigned long node,
 					    const char *uname, int depth, void *data)
 {
 	unsigned long *lprop;
+	u32 *prop;
 	unsigned long l;
 	char *p;
 
@@ -760,6 +761,22 @@ static int __init early_init_dt_scan_chosen(unsigned long node,
                crashk_res.end = crashk_res.start + *lprop - 1;
 #endif
 
+#ifdef CONFIG_BLK_DEV_INITRD
+	DBG("Looking for initrd properties... ");
+	prop = of_get_flat_dt_prop(node, "linux,initrd-start", &l);
+	if (prop) {
+		initrd_start = (unsigned long)__va(of_read_ulong(prop, l/4));
+		prop = of_get_flat_dt_prop(node, "linux,initrd-end", &l);
+		if (prop) {
+			initrd_end = (unsigned long)__va(of_read_ulong(prop, l/4));
+			initrd_below_start_ok = 1;
+		} else {
+			initrd_start = 0;
+		}
+	}
+	DBG("initrd_start=0x%lx  initrd_end=0x%lx\n", initrd_start, initrd_end);
+#endif /* CONFIG_BLK_DEV_INITRD */
+
 	/* Retreive command line */
  	p = of_get_flat_dt_prop(node, "bootargs", &l);
 	if (p != NULL && l > 0)
@@ -926,6 +943,12 @@ static void __init early_reserve_mem(void)
 	self_size = initial_boot_params->totalsize;
 	lmb_reserve(self_base, self_size);
 
+#ifdef CONFIG_BLK_DEV_INITRD
+	/* then reserve the initrd, if any */
+	if (initrd_start && (initrd_end > initrd_start))
+		lmb_reserve(__pa(initrd_start), initrd_end - initrd_start);
+#endif /* CONFIG_BLK_DEV_INITRD */
+
 #ifdef CONFIG_PPC32
 	/* 
 	 * Handle the case where we might be booting from an old kexec

arch/powerpc/kernel/setup-common.c

@@ -304,26 +304,8 @@ struct seq_operations cpuinfo_op = {
 void __init check_for_initrd(void)
 {
 #ifdef CONFIG_BLK_DEV_INITRD
-	const unsigned int *prop;
-	int len;
-
-	DBG(" -> check_for_initrd()\n");
-
-	if (of_chosen) {
-		prop = get_property(of_chosen, "linux,initrd-start", &len);
-		if (prop != NULL) {
-			initrd_start = (unsigned long)
-				__va(of_read_ulong(prop, len / 4));
-			prop = get_property(of_chosen,
-					"linux,initrd-end", &len);
-			if (prop != NULL) {
-				initrd_end = (unsigned long)
-					__va(of_read_ulong(prop, len / 4));
-				initrd_below_start_ok = 1;
-			} else
-				initrd_start = 0;
-		}
-	}
+	DBG(" -> check_for_initrd()  initrd_start=0x%lx  initrd_end=0x%lx\n",
+	    initrd_start, initrd_end);
 
 	/* If we were passed an initrd, set the ROOT_DEV properly if the values
 	 * look sensible. If not, clear initrd reference.