tile: expect new initramfs name from hypervisor file system

commit ff7f3efb upstream.

The current Tilera boot infrastructure now provides the initramfs
to Linux as a Tilera-hypervisor file named "initramfs", rather than
"initramfs.cpio.gz", as before.  (This makes it reasonable to use
other compression techniques than gzip on the file without having to
worry about the name causing confusion.)  Adapt to use the new name,
but also fall back to checking for the old name.

Cc'ing to stable so that older kernels will remain compatible with
newer Tilera boot infrastructure.
Signed-off-by: Chris Metcalf <cmetcalf@tilera.com>
[bwh: Backported to 3.2: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

arch/tile/kernel/setup.c

@@ -914,7 +914,7 @@ void __cpuinit setup_cpu(int boot)
 #ifdef CONFIG_BLK_DEV_INITRD
 
 static int __initdata set_initramfs_file;
-static char __initdata initramfs_file[128] = "initramfs.cpio.gz";
+static char __initdata initramfs_file[128] = "initramfs";
 
 static int __init setup_initramfs_file(char *str)
 {
@@ -928,9 +928,9 @@ static int __init setup_initramfs_file(char *str)
 early_param("initramfs_file", setup_initramfs_file);
 
 /*
- * We look for an additional "initramfs.cpio.gz" file in the hvfs.
- * If there is one, we allocate some memory for it and it will be
- * unpacked to the initramfs after any built-in initramfs_data.
+ * We look for a file called "initramfs" in the hvfs.  If there is one, we
+ * allocate some memory for it and it will be unpacked to the initramfs.
+ * If it's compressed, the initd code will uncompress it first.
  */
 static void __init load_hv_initrd(void)
 {
@@ -940,10 +940,16 @@ static void __init load_hv_initrd(void)
 
 	fd = hv_fs_findfile((HV_VirtAddr) initramfs_file);
 	if (fd == HV_ENOENT) {
-		if (set_initramfs_file)
+		if (set_initramfs_file) {
 			pr_warning("No such hvfs initramfs file '%s'\n",
 				   initramfs_file);
-		return;
+			return;
+		} else {
+			/* Try old backwards-compatible name. */
+			fd = hv_fs_findfile((HV_VirtAddr)"initramfs.cpio.gz");
+			if (fd == HV_ENOENT)
+				return;
+		}
 	}
 	BUG_ON(fd < 0);
 	stat = hv_fs_fstat(fd);