S390: ccw firmware: Add start assembly

We want to write most of our code in C, so add a small assembly
stub that jumps straight into C code for us to continue booting.

Signed-off-by: Alexander Graf <agraf@suse.de>

diff --git a/pc-bios/s390-ccw/start.S b/pc-bios/s390-ccw/start.S
new file mode 100644 (file)
index 0000000..c2b9a19
--- /dev/null
+++ b/pc-bios/s390-ccw/start.S
@@ -0,0 +1,16 @@
+/*
+ * First stage boot loader for virtio devices. The compiled output goes
+ * into the pc-bios directory of qemu.
+ *
+ * Copyright (c) 2013 Alexander Graf <agraf@suse.de>
+ *
+ * This work is licensed under the terms of the GNU GPL, version 2 or (at
+ * your option) any later version. See the COPYING file in the top-level
+ * directory.
+ */
+
+        .globl _start
+_start:
+
+larl   %r15, stack + 0x8000    /* Set up stack */
+j      main                    /* And call C */