* Authors: Alexander Graf <agraf@suse.de>
*/
-#define NO_QEMU_PROTOS
-#include "../../hw/fw_cfg.h"
+#include "optionrom.h"
-#define BIOS_CFG_IOPORT_CFG 0x510
-#define BIOS_CFG_IOPORT_DATA 0x511
+#define BOOT_ROM_PRODUCT "multiboot loader"
#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 1 /* (_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 */
+#define GS_PROT_JUMP 0
+#define GS_GDT_DESC 6
+
+
+BOOT_ROM_START
run_multiboot:
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)
+ /* set up a long jump descriptor that is PC relative */
- /* fix the prot mode indirect jump to be 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
- mov %ebx, (prot_jump)
+ 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 */
- read_fw FW_CFG_INITRD_SIZE
+ mov %fs:48, %eax
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
+ /* 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
- /* 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
/* e820 */
movl $0x0000e820, %eax
/* 'SMAP' magic */
int $0x15
mmap_check_entry:
- /* last entry? then we're done */
+ /* Error or last entry already 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
+ /* 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
- /* %di = 4 + (entry_number * 24) */
- add $4, %di
- jmp mmap_loop
+
+ /* 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 %cs:gdt_desc
+ data32 lgdt %gs:GS_GDT_DESC
/* get us to protected mode now */
movl $1, %eax
/* the LJMP sets CS for us and gets us to 32-bit */
ljmp:
- data32 ljmp *%cs:prot_jump
+ data32 ljmp *%gs:GS_PROT_JUMP
prot_mode:
.code32
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_ADDR
+ read_fw FW_CFG_KERNEL_ENTRY
mov %eax, %ecx
/* EBX contains a pointer to the bootinfo struct */
/* Variables */
.align 4, 0
-old_int19: .long 0
-
prot_jump: .long prot_mode
.short 8
.short (5 * 8) - 1
.long gdt
-.align 512, 0
-_end:
-
+BOOT_ROM_END
projects / qemu.git / blobdiff