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Date: Sat, 05 Sep 2009 09:16:41 +0300
From: Alexander Motin <mav@FreeBSD.org>
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To: John Baldwin <jhb@freebsd.org>
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Cc: svn-src-head@freebsd.org, svn-src-all@freebsd.org,
	Scott Long <scottl@samsco.org>, src-committers@freebsd.org,
	Ivan Voras <ivoras@freebsd.org>
Subject: Re: svn commit: r196777 - head/sys/dev/ahci
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John Baldwin wrote:
> On Thursday 03 September 2009 3:45:07 pm Ivan Voras wrote:
>> But ciss doesn't reference it at all so either it deviously assumes it
>> or is independent of it.
> 
> Actually, it may be much worse, it may be that the author of ciss(4) new that 
> ciss(4)'s largest supported I/O size was larger than 128k so they didn't 
> bother handling the limit at all giving the false impression the hardware has 
> no limit.

In cases of ATA and CAM infrastructures it was is so, that if driver
does not sets max_iosize or maxio respectively, it uses DFLTPHYS. So
problem is only about non-ATA/CAM RAIDs or cases where wrong value could
be specified explicitly.

ciss(4) driver was explicitly limited to 64K, until somebody could
review it's capabilities.

-- 
Alexander Motin