2 * $NetBSD: gatea20.c,v 1.2 1997/10/29 00:32:49 fvdl Exp $
3 * $FreeBSD: src/sys/boot/i386/libi386/gatea20.c,v 1.4 2003/08/25 23:28:31 obrien Exp $
4 * $DragonFly: src/sys/boot/i386/libi386/Attic/gatea20.c,v 1.3 2003/11/10 06:08:36 dillon Exp $
7 /* extracted from freebsd:sys/i386/boot/biosboot/io.c */
10 #include <machine/cpufunc.h>
12 #include <bootstrap.h>
16 #define K_RDWR 0x60 /* keyboard data & cmds (read/write) */
17 #define K_STATUS 0x64 /* keyboard status */
18 #define K_CMD 0x64 /* keybd ctlr command (write-only) */
20 #define K_OBUF_FUL 0x01 /* output buffer full */
21 #define K_IBUF_FUL 0x02 /* input buffer full */
23 #define KC_CMD_WIN 0xd0 /* read output port */
24 #define KC_CMD_WOUT 0xd1 /* write output port */
25 #define KB_A20 0x9f /* enable A20,
27 enable output buffer full interrupt
32 * Gate A20 for high memory
34 static unsigned char x_20 = KB_A20;
37 __asm("pushfl ; cli");
41 while (inb(K_STATUS) & K_IBUF_FUL);
42 while (inb(K_STATUS) & K_OBUF_FUL)
45 outb(K_CMD, KC_CMD_WOUT);
47 while (inb(K_STATUS) & K_IBUF_FUL);
50 while (inb(K_STATUS) & K_IBUF_FUL);