Date: 13 Oct 1999 11:22:35 +0000 From: Randell Jesup <rjesup@wgate.com> To: "Justin T. Gibbs" <gibbs@plutotech.com>, Gerard Roudier <groudier@club-internet.fr>, scsi@FreeBSD.ORG Subject: Re: Driver for GDT6517RD RAID controller Message-ID: <ybuzoxny078.fsf@jesup.eng.tvol.net.jesup.eng.tvol.net> In-Reply-To: "Justin T. Gibbs"'s message of "Tue, 12 Oct 1999 17:45:03 -0600" References: <199910122345.RAA03158@caspian.plutotech.com>
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"Justin T. Gibbs" <gibbs@caspian.plutotech.com> writes:
>In this scenario you can return BUSY status. The scenario I want to
>avoid is that you have run out of controller resources to actually
>tell the controller to return BUSY status. There are controllers
>(like the aic7xxx chips) where having pending accept ccbs does
>not consume any controller resources, but outstanding continue target
>I/O or scsi I/O operations do.
Really?
> If you expend all of your resources
>on active, but disconnected, transactions and a selection without
>disconnect occurs, you are deadlocked if you can't ensure the peripheral
>driver that will handle the selection has controller resources to play
>with.
Which resources are those? This seems very strange to me - I
can't imagine what resources would be required in order to return BUSY
that might not be available. Even if that's true, it sounds like a problem
with the driver design.
Thanks for the info though; I never would have expected that
a driver might _not_ be able to return BUSY...
--
Randell Jesup, Worldgate Communications, ex-Scala, ex-Amiga OS team ('88-94)
rjesup@wgate.com
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