28 		status = inb(0x64);  in empty_8042()
29 		if (status == 0xff) {  in empty_8042()
37 			(void)inb(0x60);  in empty_8042()
40 			return 0;  in empty_8042()
48    used as a test is the int $0x80 vector, which should be safe. */
50 #define A20_TEST_ADDR	(4*0x80)
56 	int ok = 0;  in a20_test()
59 	set_fs(0x0000);  in a20_test()
60 	set_gs(0xffff);  in a20_test()
67 		ok = rdgs32(A20_TEST_ADDR+0x10) ^ ctr;  in a20_test()
94 	ireg.ax = 0x2401;  in enable_a20_bios()
95 	intcall(0x15, &ireg, NULL);  in enable_a20_bios()
102 	outb(0xd1, 0x64);	/* Command write */  in enable_a20_kbc()
105 	outb(0xdf, 0x60);	/* A20 on */  in enable_a20_kbc()
108 	outb(0xff, 0x64);	/* Null command, but UHCI wants it */  in enable_a20_kbc()
116 	port_a = inb(0x92);	/* Configuration port A */  in enable_a20_fast()
117 	port_a |=  0x02;	/* Enable A20 */  in enable_a20_fast()
118 	port_a &= ~0x01;	/* Do not reset machine */  in enable_a20_fast()
119 	outb(port_a, 0x92);  in enable_a20_fast()
123  * Actual routine to enable A20; return 0 on ok, -1 on failure
137 		       return 0;  in enable_a20()
139 	       /* Next, try the BIOS (INT 0x15, AX=0x2401) */  in enable_a20()
142 		       return 0;  in enable_a20()
148 		       return 0; /* BIOS worked, but with delayed reaction */  in enable_a20()
153 			       return 0;  in enable_a20()
159 		       return 0;  in enable_a20()