diff options
Diffstat (limited to 'head.S')
| -rw-r--r-- | head.S | 51 |
1 files changed, 12 insertions, 39 deletions
@@ -62,53 +62,26 @@ _start: cld cli - - /* Set our own GDT and IDT, don't derive from IAFW */ - lgdtl %cs:gdtr - lidtl %cs:idtr - - /* Load segment registers per protected mode kernel entry requirement: - * CS=0x10, - * DS=ES=SS=FS=GS=0x18 - */ - ljmp $__BOOT_CS, $1f -1: + /* setup stack, because we are heading off to "C" */ + movl $STACK_OFFSET, %esp + calll bootstub + /* after call bootstub, GDT is set, IDT is clear + * eax contains 32-bit entry of bzImage + */ movl $__BOOT_DS, %ebx movl %ebx, %ds movl %ebx, %es movl %ebx, %fs movl %ebx, %gs movl %ebx, %ss - - /* setup stack, because we are heading off to "C" */ - movl $STACK_OFFSET, %esp - - /* bootstub() returns 32bit entry address of bzImage, stored in eax */ - calll bootstub - + ljmp $__BOOT_CS,$1f +1: /* tell kernel where is boot_param */ movl $(BOOT_PARAMS_OFFSET), %esi xor %ebp, %ebp xor %edi, %edi - xor %ebx, %ebx - - /* Jump to the 32-bit entrypoint */ - jmpl *%eax - - .balign 8 -gdt: - .quad 0 - .quad 0 - .quad GDT_ENTRY(0xc09b, 0, 0xfffff) - .quad GDT_ENTRY(0xc093, 0, 0xfffff) -gdtr: - .word 4*8-1 - .long gdt + mov %eax, %ecx + mov mb_magic, %eax + mov mb_info, %ebx - .balign 8 -idt: - .quad 0 - .quad 0 -idtr: - .word 2*8-1 - .long idt + jmpl *%ecx # Jump to the 32-bit entrypoint |