File grub-0.97-gate-a20.patch of Package grub
diff -ur grub-0.97.orig/stage2/asm.S grub-0.97/stage2/asm.S --- grub-0.97.orig/stage2/asm.S 2009-11-12 16:35:33.000000000 -0500 +++ grub-0.97/stage2/asm.S 2009-11-12 17:39:23.000000000 -0500 @@ -1622,36 +1622,57 @@ */ ENTRY(gateA20) + pushl %ebx + pushl %edx + call testA20 + jnz 1f + call A20_BIOS + call testA20 + jnz 1f + call A20_PORT92 + call testA20 + jnz 1f + call A20_KBDCTL + call testA20 + jnz 1f + movl $0,%eax + jmp 2f +1: + movl $-1,%eax +2: + popl %edx + popl %ebx + ret + +testA20: + movl 0x500,%eax + movl 0x100500,%ebx + notl %eax + movl %eax,0x100500 + cmpl %eax,0x500 + pushfl + movl %ebx,0x100500 + notl %eax + movl %eax,0x500 + popfl + ret + +A20_BIOS: /* first, try a BIOS call */ - pushl %ebp - movl 8(%esp), %edx call EXT_C(prot_to_real) .code16 - movw $0x2400, %ax - testw %dx, %dx - jz 1f - incw %ax + movw $0x2401, %ax 1: stc int $0x15 - jnc 2f - - /* set non-zero if failed */ - movb $1, %ah - - /* save the status */ -2: movb %ah, %dl DATA32 call EXT_C(real_to_prot) .code32 - - popl %ebp - testb %dl, %dl - jnz 3f ret -3: /* +A20_PORT92: + /* * try to switch gateA20 using PORT92, the "Fast A20 and Init" * register */ @@ -1661,20 +1682,18 @@ cmpb $0xff, %al jz 6f - /* set or clear bit1, the ALT_A20_GATE bit */ - movb 4(%esp), %ah - testb %ah, %ah - jz 4f + /* set bit1, the ALT_A20_GATE bit */ orb $2, %al - jmp 5f -4: and $0xfd, %al + /* and $0xfd, %al */ /* clear the INIT_NOW bit; don't accidently reset the machine */ -5: and $0xfe, %al + and $0xfe, %al outb %al, %dx +6: + ret - -6: /* use keyboard controller */ +A20_KBDCTL: + /* use keyboard controller */ pushl %eax call gloop1 @@ -1684,18 +1703,11 @@ gloopint1: inb $K_STATUS - cmpb $0xff, %al - jz gloopint1_done andb $K_IBUF_FUL, %al jnz gloopint1 -gloopint1_done: movb $KB_OUTPUT_MASK, %al - cmpb $0, 0x8(%esp) - jz gdoit - orb $KB_A20_ENABLE, %al -gdoit: outb $K_RDWR call gloop1 @@ -1710,8 +1722,6 @@ gloop1: inb $K_STATUS - cmpb $0xff, %al - jz gloop2ret andb $K_IBUF_FUL, %al jnz gloop1
