i386 doesn't have this bug?

quoted text
> the boot loader passes a variable that identifies the disk its
> booting off made up of a bunch of fields like adapter, controller,
> disk, and partition offsets, plus a table of all the disks it can
> see which includes this id and a checksum.
> 
> the kernel goes through and checksums the disks and then maps that
> back to the id associated with that disk, and then compares some
> of the fields in those ids against the boot disks id to figure out
> which disk its on.
> 
> the problem is we overflow one of those fields (the disk id one).
> since the other fields are set to 0 by the boot loader, this doesnt
> really matter that much. however, since those fields are now
> significant because of the overflow, we should compare them too.
> 
> this prevents sd16 being matched as the boot disk after sd0 on my
> system with 25 disks attached.
> 
> sorry if this explanation sucks.
> 
> ok?
> 
> Index: dkcsum.c
> ===================================================================
> RCS file: /cvs/src/sys/arch/amd64/amd64/dkcsum.c,v
> retrieving revision 1.15
> diff -u -p -r1.15 dkcsum.c
> --- dkcsum.c	10 Dec 2008 23:41:19 -0000	1.15
> +++ dkcsum.c	2 Dec 2010 05:08:25 -0000
> @@ -71,10 +71,13 @@ dkcsumattach(void)
>  
>  #ifdef DEBUG
>  	printf("dkcsum: bootdev=%#x\n", bootdev);
> -	for (bdi = bios_diskinfo; bdi->bios_number != -1; bdi++)
> -		if (bdi->bios_number & 0x80)
> -			printf("dkcsum: BIOS drive %#x checksum is %#x\n",
> -			    bdi->bios_number, bdi->checksum);
> +	for (bdi = bios_diskinfo; bdi->bios_number != -1; bdi++) {
> +		if (bdi->bios_number & 0x80) {
> +			printf("dkcsum: BIOS drive %#x bsd_dev=%#x "
> +			    "checksum=%#x\n", bdi->bios_number, bdi->bsd_dev,
> +			    bdi->checksum);
> +		}
> +	}
>  #endif
>  	pribootdev = altbootdev = 0;
>  
> @@ -180,7 +183,9 @@ dkcsumattach(void)
>  		 */
>  
>  		/* B_TYPE dependent hd unit counting bootblocks */
> -		if ((B_TYPE(bootdev) == B_TYPE(hit->bsd_dev)) &&
> +		if ((B_ADAPTOR(bootdev) == B_ADAPTOR(hit->bsd_dev)) &&
> +		    (B_CONTROLLER(bootdev) == B_CONTROLLER(hit->bsd_dev)) &&
> +		    (B_TYPE(bootdev) == B_TYPE(hit->bsd_dev)) &&
>  		    (B_UNIT(bootdev) == B_UNIT(hit->bsd_dev))) {
>  			int type, ctrl, adap, part, unit;