memdisk: Fix INT 0x13, AH==0x15 disk drive probe

The function might return CF==0 ("success"), but could
include AH==0 ("no such drive").  This is the case on
at least a number of Dell models.  Now we check AH, too.

Signed-off-by: Shao Miller <shao.miller@yrdsb.edu.on.ca>

diff --git a/memdisk/dskprobe.c b/memdisk/dskprobe.c
index 8c2f27b..84400a8 100644 (file)
--- a/memdisk/dskprobe.c
+++ b/memdisk/dskprobe.c
@@ -72,7 +72,7 @@ static int probe_int13h_15h(uint8_t drive, com32sys_t * regs)
 
     memset(regs, 0, sizeof *regs);
     probe_any(0x15, drive, regs);
-    present = !(regs->eflags.l & 1);
+    present = !(regs->eflags.l & 1) && regs->eax.b[1];
     dskprobe_printf("  AH15: CF%d AH%02x\n", regs->eflags.l & 1,
                    regs->eax.b[1]);
     return present;