1 files changed, 97 insertions, 0 deletions
diff --git a/payloads/libpayload/arch/i386/head.S b/payloads/libpayload/arch/i386/head.S
new file mode 100644
index 0000000000..db18a5195f
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+++ b/payloads/libpayload/arch/i386/head.S
@@ -0,0 +1,97 @@
+/*
+ * This file is part of the libpayload project.
+ *
+ * Copyright (C) 2008 Advanced Micro Devices, Inc.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. The name of the author may not be used to endorse or promote products
+ *    derived from this software without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+	.code32
+	.global _entry, _leave
+	.text
+	.align 4
+
+/*
+ * Our entry point - assume that the CPU is in 32 bit protected mode and
+ * all segments are in a flat model. That's our operating mode, so we won't
+ * change anything.
+ */
+_entry:
+	call _init
+
+	/* We're back - go back to the bootloader. */
+	ret
+
+	.align 4
+
+#define MB_MAGIC 0x1BADB002
+#define MB_FLAGS 0x00010003
+
+mb_header:
+	.long MB_MAGIC
+	.long MB_FLAGS
+	.long -(MB_MAGIC + MB_FLAGS)
+	.long mb_header
+	.long _start
+	.long _edata
+	.long _end
+	.long _init
+
+/*
+ * This function saves off the previous stack and switches us to our
+ * own execution environment.
+ */
+_init:
+	/* No interrupts, please. */
+	cli
+
+	/* Store current stack pointer. */
+	movl %esp, %esi
+
+	/* Store EAX and EBX */
+
+	movl %eax,loader_eax
+	movl %ebx,loader_ebx
+
+	/* Setup new stack. */
+	movl $_stack, %ebx
+
+	movl %ebx, %esp
+
+	/* Save old stack pointer. */
+	pushl %esi
+
+	/* Let's rock. */
+	call start_main
+
+	/* %eax has the return value - pass it on unmolested */
+_leave:
+	/* Get old stack pointer. */
+	popl %ebx
+
+	/* Restore old stack. */
+	movl %ebx, %esp
+
+	/* Return to the original context. */
+	ret