A possible approach to the IDE shadow problem

[Alan Cox <alan@redhat.com>]

Some IDE devices don't decode master/slave (notably PCMCIA CF stuff), other
stuff has flash and disk mixed. Either assumption is broken so the kernel
sometimes double detects devices like microdrives. 

It occurred to me there may be a very easy way to fix this, so this patch
is for comment [Linus don't apply it yet 8)]


diff -u --new-file --recursive --exclude-from /usr/src/exclude linux-2.6.7/drivers/ide/ide-probe.c 2.6.7-ac/drivers/ide/ide-probe.c
--- linux-2.6.7/drivers/ide/ide-probe.c	2004-06-16 21:11:35.907453312 +0100
+++ 2.6.7-ac/drivers/ide/ide-probe.c	2004-06-16 21:19:28.422620088 +0100
@@ -749,6 +749,16 @@
 		ide_drive_t *drive = &hwif->drives[unit];
 		drive->dn = (hwif->channel ? 2 : 0) + unit;
 		(void) probe_for_drive(drive);
+		if (drive->present && hwif->present && unit == 1)
+		{
+			if(strcmp(hwif->drives[0].id->model, drive->id->model) == 0 &&
+			   strcmp(drive->id->model, "UNKNOWN") && /* Don't do this for non ATA or for noprobe */
+			   strncmp(hwif->drives[0].id->serial_no, drive->id->serial_no, 20) == 0)
+			{
+				printk(KERN_WARNING "ide-probe: ignoring undecoded slave\n");
+				drive->present = 0;
+			}
+		}
 		if (drive->present && !hwif->present) {
 			hwif->present = 1;
 			if (hwif->chipset != ide_4drives ||