Testing CAM wrapper for ata(4) controller drivers

Alexander Motin mav at FreeBSD.org
Sun Dec 13 00:20:51 UTC 2009

Juergen Lock wrote:
> In article <4B20EDD2.5000102 at FreeBSD.org> you write:
>> Andriy Gapon wrote:
>>> on 10/12/2009 01:07 Alexander Best said the following:
>>>> ah. i see. thanks for the hint. sorry mav for blaming ATA_CAM. ;) would be
>>>> nice if this would be fixed at some point. i believe the problem also applies
>>>> to tape drives, usb memory card readers, etc.? so generally speaking: any
>>>> devices which allow new media insertion, but don't disconnect/re-attach
>>>> from/to CAM.
>>> Yes, we need to get some notification that media is changed and then trigger geom
>>> action.  Right now there is no notification from hardware in most cases and there
>>> is no support for handling that in drivers, AFAIK.  Maybe ahci driver starts to
>>> add support for that.  So either something needs to poll media for changes or a
>>> user has to trigger some action explicitly.  No magic.
>> Both ahci and siis drivers already have SATA Asynchronous Notifications
>> support, that was especially made to do that. Now AN used to receive
>> messages from PMP about fan-out ports physical events and working fine.
>> What is needed: SATA ATAPI device with AN support (haven't checked if
>> there are ones on the market), enable these messages, improve cd driver
>> to make some useful activity (have no idea how) on such events.
> Doesn't scsi have `unit attention' to notify media changes?  Or does
> that not work as expected with atapi?

Haven't checked. Will try it tomorrow. But any way it require device
polling. SATA AN same time is device-initiated real-time event.

Alexander Motin

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