From owner-freebsd-scsi  Sun Jul 13 16:47:31 1997
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To: "Justin T. Gibbs" <gibbs@plutotech.com>
cc: Simon Shapiro <Shimon@i-Connect.Net>, filo@yahoo.com,
        freebsd-SCSI@FreeBSD.ORG
Subject: Re: problems with reboot 
In-reply-to: Your message of "Sun, 13 Jul 1997 09:55:37 MDT."
             <199707131555.JAA25833@pluto.plutotech.com> 
From: David Greenman <dg@root.com>
Reply-To: dg@root.com
Date: Sun, 13 Jul 1997 16:47:48 -0700
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>>>There is an issue with FreeBSD shutdown not waiting for the DPt to flush
>>>caches as it should.
>>
>>   Should be easy to fix by adding a shutdown routine to the driver that waits
>>for the flushes to complete.
>>
>>-DG
>>
>>David Greenman
>>Core-team/Principal Architect, The FreeBSD Project
>
>If we're not waiting for the last close to complete, that is a bug
>that should be fixed.  I believe that Simon added a syncronize
>cache command into sdclose which should address the DPT issue so
>long as it actually gets performed and we wait for it to complete.
>The syncronize cache command may be required for other disk devices
>as well, and a generic solution is always better than a controller
>specific one.

   The shutdown code waits for all buffers to be flushed, but the code has no
way of knowing if the controller actually committed the data to disk. If a
disk controller indicates I/O completion/success before the data is actually
written to disk, then it seems to me that forcing the cache flush would be
a controller specific operation. Yes?

-DG

David Greenman
Core-team/Principal Architect, The FreeBSD Project