diff options
Diffstat (limited to 'i386/i386at/boothdr.S')
| -rw-r--r-- | i386/i386at/boothdr.S | 37 |
1 files changed, 37 insertions, 0 deletions
diff --git a/i386/i386at/boothdr.S b/i386/i386at/boothdr.S index 45cd599f..567851e4 100644 --- a/i386/i386at/boothdr.S +++ b/i386/i386at/boothdr.S @@ -39,6 +39,19 @@ boot_hdr: #endif /* __ELF__ */ boot_entry: + /* use segmentation to offset ourself. */ + lgdt boot_gdt_descr - KERNELBASE + ljmp $8,$0f +0: + movw $0,%ax + movw %ax,%ds + movw %ax,%es + movw %ax,%fs + movw %ax,%gs + movw $16,%ax + movw %ax,%ds + movw %ax,%es + movw %ax,%ss /* Switch to our own interrupt stack. */ movl $_intstack+INTSTACK_SIZE,%esp @@ -80,3 +93,27 @@ iplt_done: .comm _intstack,INTSTACK_SIZE +.align 16 + .word 0 +boot_gdt_descr: + .word 3*8+7 + .long boot_gdt - KERNELBASE +.align 16 +boot_gdt: + /* 0 */ + .quad 0 + /* boot CS = 8 */ + .word 0xffff + .word (-KERNELBASE) & 0xffff + .byte ((-KERNELBASE) >> 16) & 0xff + .byte 0x9a + .byte 0xcf + .byte ((-KERNELBASE) >> 24) & 0xff + /* boot DS = 8 */ + .word 0xffff + .word (-KERNELBASE) & 0xffff + .byte ((-KERNELBASE) >> 16) & 0xff + .byte 0x92 + .byte 0xcf + .byte ((-KERNELBASE) >> 24) & 0xff + |