[issue1648] AHCI driver reports FIS structure fails

Matthew Dillon dillon at apollo.backplane.com
Mon Jan 11 21:28:00 PST 2010

:Edward O'Callaghan <eocallaghan at auroraux.org> added the comment:
:Everything is detected on that machine and seems to be working fine, just
:thought I would report the messages, they looked nasty.

    It's ok.  What it is doing is probing for a port multiplier.  The only
    way one can determine if a port multiplier is on the port is to
    probe target 15, and of course this will fail if there is no port

    The probing has to be done whether or not a device is probed on
    target 0, because when a PM is attached target 0 represents slot #0
    behind the PM.

    Basically Intel screwed the standard up to try to make it easier for
    BIOS writers to boot from devices behind a port multiplier.  Even worse,
    there is no safe value for timing-out a software reset command (in fact,
    on some chipsets if you timeout the command too quickly the chipset
    will brick), so the entire probe sequence runs a lot slower then it
    needs to if Intel hadn't messed up the standard.

					Matthew Dillon 
					<dillon at backplane.com>

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