Add a special command to load and start a bzImage on x86

Other architectures are supporting the uImage format used by barebox's 'bootm'
command. x86 does'nt. So, we need a special command to be able to boot the
x86 specific bzImage format.

Signed-off-by: Juergen Beisert <jbe@pengutronix.de>
Signed-off-by: Sascha Hauer <s.hauer@pengutronix.de>

1 files changed, 75 insertions, 0 deletions

diff --git a/arch/x86/lib/linux_start.S b/arch/x86/lib/linux_start.S
new file mode 100644
index 0000000000..fac2510d1c
--- /dev/null
+++ b/arch/x86/lib/linux_start.S
@@ -0,0 +1,75 @@
+/*
+ * Copyright (C) 2009 Juergen Beisert, Pengutronix
+ *
+ * Mostly stolen from the GRUB2 project
+ *  Copyright (C) 1999,2000,2001,2002,2003,2004,2005,2006,2007,2008  Free Software Foundation, Inc.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License as
+ * published by the Free Software Foundation; either version 2 of
+ * the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software
+ * Foundation, Inc., 59 Temple Place, Suite 330, Boston,
+ * MA 02111-1307 USA
+ *
+ */
+
+/**
+ * @file
+ * @brief Start the Linux real mode setup code
+ *
+ * Note: These functions are running in flat and real mode. Due to some
+ * other restrictions these routines must running from an address
+ * space below 0x10000
+ */
+
+/*
+ *   void bios_start_linux(unsigned segment)
+ *
+ */
+#ifndef DOXYGEN_SHOULD_SKIP_THIS
+
+	.section .boot.text.bios_start_linux, "ax"
+	.code32
+	.globl bios_start_linux
+	.type bios_start_linux, @function
+
+	.extern prot_to_real
+
+bios_start_linux:
+	/* 'prot_to_real' eats our eax content */
+	movl %eax, %ebx
+	addl $0x20, %eax
+	movw %ax, setup_seg
+
+	call prot_to_real
+
+	.code16
+
+	cli
+	/* all segment registers are using the same segment */
+	movw %bx, %ss
+	movw %bx, %ds
+	movw %bx, %es
+	movw %bx, %fs
+	movw %bx, %gs
+
+	/* stack for the setup code (end of heap) */
+	movw $0x9000, %sp
+
+	/* do an 'ljmp' and never return */
+	.byte	0xea
+	.word	0
+setup_seg:
+	.word	0
+
+	.code32
+
+#endif