kern/37866: Thinkpad T61 disk doesn't work in AHCI mode

[smb%cs.columbia.edu@localhost]

>Number:         37866
>Category:       kern
>Synopsis:       Thinkpad T61 disk doesn't work in AHCI mode
>Confidential:   no
>Severity:       serious
>Priority:       medium
>Responsible:    kern-bug-people
>State:          open
>Class:          sw-bug
>Submitter-Id:   net
>Arrival-Date:   Fri Jan 25 00:40:00 +0000 2008
>Originator:     Steven M. Bellovin
>Release:        NetBSD 4.99.49
>Organization:
Department of Computer Science, Columbia University
>Environment:
        
        
System: NetBSD yellowstone.machshav.com 4.99.49 NetBSD 4.99.49 (YELLOWSTONE) 
#0: Mon Jan 21 23:10:45 EST 2008 
smb%yellowstone.machshav.com@localhost:/usr/BUILD/obj/sys/arch/amd64/compile/YELLOWSTONE
 amd64
Architecture: x86_64
Machine: amd64
>Description:
        Much of the time, if I boot my machine with the disk set in the
        BIOS to AHCI mode, it doesn't see the whole disk.  This causes
        errors in finding the NetBSD partition and the root partition,
        and if you persist you'll overwrite random parts of the disk,
        including things outside of what NetBSD should be touching.

        It is not 100% reproducbile.  In tests today, it didn't happen
        if I rebooted from power-off; it did happen if I warm-booted.
        This suggests a bug in the initialization code.
>How-To-Repeat:
        See above.
>Fix:
        Set the disk to compatibility mode in the BIOS.

>Unformatted: