* other boot loaders like Grub
*/
+#define MB_INFO_SIZE 90
#define MB_INFO_FLAGS_OFFSET 0
#define MB_INFO_BOOT_DEVICE_OFFSET 12
#define MB_INFO_COMMAND_LINE_OFFSET 16
+#define CMDLINE_SIZE 256
/*
* We want to execute at 0x8000 (to be compatible with bootsector
* above 1MB. So we let Grub load us there and then relocate
* ourself to 0x8000
*/
-#define CMDLINE_BASE 0x7000
#define FREELDR_BASE 0x8000
#define INITIAL_BASE 0x200000
movw %dx,%ds
movw %dx,%es
+ /* Check for valid multiboot signature */
+ cmpl $MULTIBOOT_BOOTLOADER_MAGIC,%eax
+ jne mbfail
+
+ /* Store multiboot info in a safe place */
+ movl %ebx,%esi
+ movl $(mb_info + INITIAL_BASE - FREELDR_BASE),%edi
+ movl $MB_INFO_SIZE,%ecx
+ rep movsb
+
+ /* Save commandline */
+ movl MB_INFO_FLAGS_OFFSET(%ebx),%edx
+ testl $MB_INFO_FLAG_COMMAND_LINE,MB_INFO_FLAGS_OFFSET(%ebx)
+ jz mb3
+ movl MB_INFO_COMMAND_LINE_OFFSET(%ebx),%esi
+ movl $(cmdline + INITIAL_BASE - FREELDR_BASE),%edi
+ movl $CMDLINE_SIZE,%ecx
+mb2: lodsb
+ stosb
+ testb %al,%al
+ jz mb3
+ dec %ecx
+ jnz mb2
+mb3:
+
/* Copy to low mem */
movl $INITIAL_BASE,%esi
movl $FREELDR_BASE,%edi
/* Clear prefetch queue & correct CS,
* jump to low mem */
- ljmp $PMODE_CS, $mb2
-mb2:
+ ljmp $PMODE_CS, $mb4
+mb4:
/* Reload segment selectors */
movw $PMODE_DS,%dx
movw %dx,%ds
movw %dx,%ss
movl $STACK32ADDR,%esp
- /* Check for valid multiboot signature */
- cmpl $MULTIBOOT_BOOTLOADER_MAGIC,%eax
- jne mbfail
-
+ movl $mb_info,%ebx
/* See if the boot device was passed in */
movl MB_INFO_FLAGS_OFFSET(%ebx),%edx
testl $MB_INFO_FLAG_BOOT_DEVICE,%edx
- jz mb3
+ jz mb5
/* Retrieve boot device info */
movl MB_INFO_BOOT_DEVICE_OFFSET(%ebx),%eax
shrl $16,%eax
incb %al
movb %al,_i386BootPartition
movb %ah,_i386BootDrive
- jmp mb4
-mb3: /* No boot device known, assume first partition of first harddisk */
+ jmp mb6
+mb5: /* No boot device known, assume first partition of first harddisk */
movb $0x80,_i386BootDrive
movb $1,_i386BootPartition
-mb4:
-
- /* Check for a command line */
- xorl %eax,%eax
- testl $MB_INFO_FLAG_COMMAND_LINE,%edx
- jz mb6
- /* Copy command line to low mem*/
- movl MB_INFO_COMMAND_LINE_OFFSET(%ebx),%esi
- movl $CMDLINE_BASE,%edi
-mb5: lodsb
- stosb
- testb %al,%al
- jnz mb5
- movl $CMDLINE_BASE,%eax
mb6:
+ /* Check for command line */
+ mov $cmdline,%eax
+ testl $MB_INFO_FLAG_COMMAND_LINE,MB_INFO_FLAGS_OFFSET(%ebx)
+ jnz mb7
+ xorl %eax,%eax
+mb7:
/* GO! */
pushl %eax
EXTERN(_i386BootPartition)
.long 0
+
+.bss
+mb_info:
+ .fill MB_INFO_SIZE, 1, 0
+
+cmdline:
+ .fill CMDLINE_SIZE, 1, 0