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Date:      Thu, 30 Sep 2010 23:45:51 +0300
From:      Andriy Gapon <avg@icyb.net.ua>
To:        Alexander Motin <mav@FreeBSD.org>
Cc:        FreeBSD-Current <freebsd-current@FreeBSD.org>
Subject:   Re: letting glabel recognise a media change
Message-ID:  <4CA4F6FF.5070402@icyb.net.ua>
In-Reply-To: <4CA4CCE3.9060408@FreeBSD.org>
References:  <4CA3BD7C.9080306@feral.com> <mailpost.1285845776.1043534.73790.mailing.freebsd.current@FreeBSD.cs.nctu.edu.tw> <4CA4CCE3.9060408@FreeBSD.org>

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on 30/09/2010 20:46 Alexander Motin said the following:
> Andriy Gapon wrote:
>> on 30/09/2010 01:28 Matthew Jacob said the following:
>>> If something like that was in place, I assure you that things would start to use
>>> it very quickly.
>>
>> I am not sure about this.
>> Because, e.g. I don't see an easy way to know that media is changed in scsi_cd
>> driver.  That is, without polling.  I don't consider polling to be an easy way for
>> a number of reasons.
> 
> SATA specification defines concept of Asynchronous Notification. It is
> already used by port multipliers to report about PHY events. It is also
> supposed to be used by CD drives to report media change. I haven't seen
> such devices yet, but hope they may appear sometimes.

Would this require some reverse-path from SIM driver to peripheral driver to
deliver a notification?  Do we have one?

> And even without AN support it would be nice to implement proper
> handling for SCSI "UA - media changed" errors within CAM. It still won't
> be perfect without using polling, but probably still something.

I agree.

-- 
Andriy Gapon



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