. 修正bug。(issues #157)

stage2/asm.S

@@ -2493,13 +2493,12 @@ int13_new_ss:		.word	0
 	/* if sectors per track > 1, this is force geometry screw. */
 
 	movw	%cs:2(%bp), %ax		/* AL=Hmax, AH=Smax */
-//	testb	$62, %ah	/* Sectors > 1 means force geom, this -- */
-	testb	$63, %ah	/* Sectors > 1 means force geom, this -- */
+	testb	$62, %ah	/* Sectors > 1 means force geom, this -- */
 	jnz	drive_emulation	/* -- also leads to drive emulation */
 
 	/* ignore geom and directly map a whole drive */
 
-//1:
+1:
 	/* bit 7 of the TO_S is for in-situ primary partition(alter MBR) */
 
 	/* bits of AH:
@@ -2511,7 +2510,8 @@ int13_new_ss:		.word	0
 	 * and if AH=1, it is a normal disk access.
 	 */
 //	cmpb	$1, %ah
-//	je	1f
+	testb	$0xc0, %ah
+	je	1f
 	call	restricted_map
 1:
 	/* map a whole drive, normal access */