Introduce Virtio-loopback epsilon release:

Epsilon release introduces a new compatibility layer which make virtio-loopback
design to work with QEMU and rust-vmm vhost-user backend without require any
changes.

Signed-off-by: Timos Ampelikiotis <t.ampelikiotis@virtualopensystems.com>
Change-Id: I52e57563e08a7d0bdc002f8e928ee61ba0c53dd9

1 files changed, 232 insertions, 0 deletions

diff --git a/pc-bios/optionrom/multiboot.S b/pc-bios/optionrom/multiboot.S
new file mode 100644
index 000000000..181a4b03a
--- /dev/null
+++ b/pc-bios/optionrom/multiboot.S
@@ -0,0 +1,232 @@
+/*
+ * Multiboot Option ROM
+ *
+ * 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, see <http://www.gnu.org/licenses/>.
+ *
+ * Copyright Novell Inc, 2009
+ *   Authors: Alexander Graf <agraf@suse.de>
+ */
+
+#include "optionrom.h"
+
+#define BOOT_ROM_PRODUCT "multiboot loader"
+
+#define MULTIBOOT_MAGIC		0x2badb002
+
+#define GS_PROT_JUMP		0
+#define GS_GDT_DESC		6
+
+
+BOOT_ROM_START
+
+run_multiboot:
+
+	cli
+	cld
+
+	mov		%cs, %eax
+	shl		$0x4, %eax
+
+	/* set up a long jump descriptor that is PC relative */
+
+	/* move stack memory to %gs */
+	mov		%ss, %ecx
+	shl		$0x4, %ecx
+	mov		%esp, %ebx
+	add		%ebx, %ecx
+	sub		$0x20, %ecx
+	sub		$0x30, %esp
+	shr		$0x4, %ecx
+	mov		%cx, %gs
+
+	/* now push the indirect jump descriptor there */
+	mov		(prot_jump), %ebx
+	add		%eax, %ebx
+	movl		%ebx, %gs:GS_PROT_JUMP
+	mov		$8, %bx
+	movw		%bx, %gs:GS_PROT_JUMP + 4
+
+	/* fix the gdt descriptor to be PC relative */
+	movw		(gdt_desc), %bx
+	movw		%bx, %gs:GS_GDT_DESC
+	movl		(gdt_desc+2), %ebx
+	add		%eax, %ebx
+	movl		%ebx, %gs:GS_GDT_DESC + 2
+
+	xor		%eax, %eax
+	mov		%eax, %es
+
+	/* Read the bootinfo struct into RAM */
+	read_fw_blob_dma(FW_CFG_INITRD)
+
+	/* FS = bootinfo_struct */
+	read_fw		FW_CFG_INITRD_ADDR
+	shr		$4, %eax
+	mov		%ax, %fs
+
+	/* Account for the EBDA in the multiboot structure's e801
+	 * map.
+	 */
+	int		$0x12
+	cwtl
+	movl		%eax, %fs:4
+
+	/* ES = mmap_addr */
+	mov 		%fs:48, %eax
+	shr		$4, %eax
+	mov		%ax, %es
+
+	/* Initialize multiboot mmap structs using int 0x15(e820) */
+	xor		%ebx, %ebx
+	/* Start storing mmap data at %es:0 */
+	xor		%edi, %edi
+
+mmap_loop:
+	/* The multiboot entry size has offset -4, so leave some space */
+	add		$4, %di
+	/* entry size (mmap struct) & max buffer size (int15) */
+	movl		$20, %ecx
+	/* e820 */
+	movl		$0x0000e820, %eax
+	/* 'SMAP' magic */
+	movl		$0x534d4150, %edx
+	int		$0x15
+
+mmap_check_entry:
+	/* Error or last entry already done? */
+	jb		mmap_done
+
+mmap_store_entry:
+	/* store entry size */
+	/* old as(1) doesn't like this insn so emit the bytes instead:
+	movl		%ecx, %es:-4(%edi)
+	*/
+	.dc.b		0x26,0x67,0x66,0x89,0x4f,0xfc
+
+	/* %edi += entry_size, store as mbs_mmap_length */
+	add		%ecx, %edi
+	movw		%di, %fs:0x2c
+
+	/* Continuation value 0 means last entry */
+	test		%ebx, %ebx
+	jnz		mmap_loop
+
+mmap_done:
+	/* Calculate upper_mem field: The amount of memory between 1 MB and
+	   the first upper memory hole. Get it from the mmap. */
+	xor		%di, %di
+	mov		$0x100000, %edx
+upper_mem_entry:
+	cmp		%fs:0x2c, %di
+	je		upper_mem_done
+	add		$4, %di
+
+	/* Skip if type != 1 */
+	cmpl		$1, %es:16(%di)
+	jne		upper_mem_next
+
+	/* Skip if > 4 GB */
+	movl		%es:4(%di), %eax
+	test		%eax, %eax
+	jnz		upper_mem_next
+
+	/* Check for contiguous extension (base <= %edx < base + length) */
+	movl		%es:(%di), %eax
+	cmp		%eax, %edx
+	jb		upper_mem_next
+	addl		%es:8(%di), %eax
+	cmp		%eax, %edx
+	jae		upper_mem_next
+
+	/* If so, update %edx, and restart the search (mmap isn't ordered) */
+	mov		%eax, %edx
+	xor		%di, %di
+	jmp		upper_mem_entry
+
+upper_mem_next:
+	addl		%es:-4(%di), %edi
+	jmp		upper_mem_entry
+
+upper_mem_done:
+	sub		$0x100000, %edx
+	shr		$10, %edx
+	mov		%edx, %fs:0x8
+
+real_to_prot:
+	/* Load the GDT before going into protected mode */
+lgdt:
+	data32 lgdt	%gs:GS_GDT_DESC
+
+	/* get us to protected mode now */
+	movl		$1, %eax
+	movl		%eax, %cr0
+
+	/* the LJMP sets CS for us and gets us to 32-bit */
+ljmp:
+	data32 ljmp	*%gs:GS_PROT_JUMP
+
+prot_mode:
+.code32
+
+	/* initialize all other segments */
+	movl		$0x10, %eax
+	movl		%eax, %ss
+	movl		%eax, %ds
+	movl		%eax, %es
+	movl		%eax, %fs
+	movl		%eax, %gs
+
+	/* Read the kernel and modules into RAM */
+	read_fw_blob_dma(FW_CFG_KERNEL)
+
+	/* Jump off to the kernel */
+	read_fw		FW_CFG_KERNEL_ENTRY
+	mov		%eax, %ecx
+
+	/* EBX contains a pointer to the bootinfo struct */
+	read_fw		FW_CFG_INITRD_ADDR
+	movl		%eax, %ebx
+
+	/* EAX has to contain the magic */
+	movl		$MULTIBOOT_MAGIC, %eax
+ljmp2:
+	jmp		*%ecx
+
+/* Variables */
+.align 4, 0
+prot_jump:	.long prot_mode
+		.short 8
+
+.align 4, 0
+gdt:
+	/* 0x00 */
+.byte	0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00, 0x00
+
+	/* 0x08: code segment (base=0, limit=0xfffff, type=32bit code exec/read, DPL=0, 4k) */
+.byte	0xff, 0xff, 0x00, 0x00, 0x00, 0x9a, 0xcf, 0x00
+
+	/* 0x10: data segment (base=0, limit=0xfffff, type=32bit data read/write, DPL=0, 4k) */
+.byte	0xff, 0xff, 0x00, 0x00, 0x00, 0x92, 0xcf, 0x00
+
+	/* 0x18: code segment (base=0, limit=0x0ffff, type=16bit code exec/read/conf, DPL=0, 1b) */
+.byte	0xff, 0xff, 0x00, 0x00, 0x00, 0x9e, 0x00, 0x00
+
+	/* 0x20: data segment (base=0, limit=0x0ffff, type=16bit data read/write, DPL=0, 1b) */
+.byte	0xff, 0xff, 0x00, 0x00, 0x00, 0x92, 0x00, 0x00
+
+gdt_desc:
+.short	(5 * 8) - 1
+.long	gdt
+
+BOOT_ROM_END