--- /dev/null
+/*
+ * 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(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(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
Code Review / kvmfornfv.git / blobdiff