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2005-07-17 Yoshinori Okuji <okuji@enbug.org>

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* conf/i386-pc.rmk (pxeboot_img_LDFLAGS): The text address should
	be 0x7C00 instead of 0x8000.

	* boot/i386/pc/pxeboot.S: Rewritten.

	* kern/i386/pc/startup.S (gate_a20_try_bios): No need to specify
	EXT_C.
	(gate_a20_check_state): Read a byte from 0x108000. Invert the
	result.
This commit is contained in:
okuji 2005-07-16 22:06:33 +00:00
parent 654fc59fe4
commit ebedfd0003
5 changed files with 44 additions and 35 deletions
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26
kern/i386/pc/startup.S
View file

@ -396,7 +396,7 @@ gate_a20_test_current_state:
gate_a20_try_bios:
/* second, try a BIOS call */
pushl %ebp
call EXT_C(prot_to_real)
call prot_to_real
.code16
movw $0x2400, %ax
@ -405,7 +405,7 @@ gate_a20_try_bios:
incw %ax
1: int $0x15
DATA32 call EXT_C(real_to_prot)
DATA32 call real_to_prot
.code32
popl %ebp
@ -413,7 +413,7 @@ gate_a20_try_bios:
cmpb %al, %dl
jnz gate_a20_try_keyboard_controller
ret
gate_a20_flush_keyboard_buffer:
inb $0x64
andb $0x02, %al
@ -449,7 +449,7 @@ gate_a20_try_keyboard_controller:
movb $0xff, %al
outb $0x64
call gate_a20_flush_keyboard_buffer
call gate_a20_check_state
cmpb %al, %dl
jnz gate_a20_try_system_control_port_a
@ -484,32 +484,36 @@ gate_a20_check_state:
pushl %ebx
pushl %ecx
xorl %eax, %eax
/* compare the byte at 0x2000 with that at 0x102000 */
/* compare the byte at 0x8000 with that at 0x108000 */
movl $GRUB_BOOT_MACHINE_KERNEL_ADDR, %ebx
pushl %ebx
/* save the original byte in CL */
movb (%ebx), %cl
/* store the value at 0x102000 in AL */
/* store the value at 0x108000 in AL */
addl $0x100000, %ebx
movb (%ebx), %al
/* try to set one less value at 0x2000 */
/* try to set one less value at 0x8000 */
popl %ebx
movb %al, %ch
decb %ch
movb %ch, (%ebx)
/* serialize */
outb $0x80
outb $0x80
/* store the value at 0x2000 in CH */
outb %al, $0x80
outb %al, $0x80
/* obtain the value at 0x108000 in CH */
pushl %ebx
addl $0x100000, %ebx
movb (%ebx), %ch
/* this result is 1 if A20 is on or 0 if it is off */
subb %ch, %al
xorb $1, %al
/* restore the original */
popl %ebx
movb %cl, (%ebx)
popl %ecx
popl %ebx
ret
#include "lzo1x.S"