diff options
Diffstat (limited to 'pc-bios')
| -rw-r--r-- | pc-bios/optionrom/multiboot.S | 209 |
1 files changed, 209 insertions, 0 deletions
diff --git a/pc-bios/optionrom/multiboot.S b/pc-bios/optionrom/multiboot.S new file mode 100644 index 0000000000..d0eec26a6a --- /dev/null +++ b/pc-bios/optionrom/multiboot.S @@ -0,0 +1,209 @@ +/* + * 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, write to the Free Software + * Foundation, 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA. + * + * Copyright Novell Inc, 2009 + * Authors: Alexander Graf <agraf@suse.de> + */ + +#define NO_QEMU_PROTOS +#include "../../hw/fw_cfg.h" + +#define BIOS_CFG_IOPORT_CFG 0x510 +#define BIOS_CFG_IOPORT_DATA 0x511 + +#define MULTIBOOT_MAGIC 0x2badb002 + +/* Read a variable from the fw_cfg device. + Clobbers: %edx + Out: %eax */ +.macro read_fw VAR + mov $\VAR, %ax + mov $BIOS_CFG_IOPORT_CFG, %dx + outw %ax, (%dx) + mov $BIOS_CFG_IOPORT_DATA, %dx + inb (%dx), %al + shl $8, %eax + inb (%dx), %al + shl $8, %eax + inb (%dx), %al + shl $8, %eax + inb (%dx), %al + bswap %eax +.endm + +.code16 +.text + .global _start +_start: + .short 0xaa55 + .byte (_end - _start) / 512 + push %eax + push %ds + + /* setup ds so we can access the IVT */ + xor %ax, %ax + mov %ax, %ds + + /* save old int 19 */ + mov (0x19*4), %eax + mov %eax, %cs:old_int19 + + /* install our int 19 handler */ + movw $int19_handler, (0x19*4) + mov %cs, (0x19*4+2) + + pop %ds + pop %eax + lret + +int19_handler: + /* DS = CS */ + movw %cs, %ax + movw %ax, %ds + + /* fall through */ + +run_multiboot: + + cli + cld + + mov %cs, %eax + shl $0x4, %eax + + /* fix the gdt descriptor to be PC relative */ + mov (gdt_desc+2), %ebx + add %eax, %ebx + mov %ebx, (gdt_desc+2) + + /* fix the prot mode indirect jump to be PC relative */ + mov (prot_jump), %ebx + add %eax, %ebx + mov %ebx, (prot_jump) + + /* FS = bootinfo_struct */ + read_fw FW_CFG_INITRD_ADDR + shr $4, %eax + mov %ax, %fs + + /* ES = mmap_addr */ + read_fw FW_CFG_INITRD_SIZE + shr $4, %eax + mov %ax, %es + + /* Initialize multiboot mmap structs using int 0x15(e820) */ + xor %ebx, %ebx + /* mmap start after first size */ + movl $4, %edi + +mmap_loop: + /* entry size (mmap struct) & max buffer size (int15) */ + movl $20, %ecx + /* store entry size */ + movl %ecx, %es:-4(%edi) + /* e820 */ + movl $0x0000e820, %eax + /* 'SMAP' magic */ + movl $0x534d4150, %edx + int $0x15 + +mmap_check_entry: + /* last entry? then we're done */ + jb mmap_done + and %bx, %bx + jz mmap_done + /* valid entry, so let's loop on */ + +mmap_store_entry: + /* %ax = entry_number * 24 */ + mov $24, %ax + mul %bx + mov %ax, %di + movw %di, %fs:0x2c + /* %di = 4 + (entry_number * 24) */ + add $4, %di + jmp mmap_loop + +mmap_done: +real_to_prot: + /* Load the GDT before going into protected mode */ +lgdt: + data32 lgdt %cs: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 *%cs: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 + + /* Jump off to the kernel */ + read_fw FW_CFG_KERNEL_ADDR + 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 +old_int19: .long 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 + +.align 512, 0 +_end: + |