Subject: Re: Messages from new aic7xxx driver
To: Jason Thorpe <thorpej@nas.nasa.gov>
From: Justin T. Gibbs <gibbs@freefall.freebsd.org>
List: current-users
Date: 05/18/1996 21:26:38
>On Sun, 19 May 1996 02:44:35 +0900 
> Noriyuki Soda <soda@sra.co.jp> wrote:
>
> > Probably this problem should be fixed in MI SCSI level, not ahc driver 
> > level, as discussed in current-users. I think Charles or Jason is 
> > working to fix this. Not ?
>
>Well, Charles and I have both thought about it, but I'm not personally 
>actively working on it ... I have some other things much higher on my 
>TODO list...I don't know about charles...

Peter Dufault and I have started work on this, but due to my move
and the release cycle at work, I don't know when we'll finish.  The
finished work should be usable by NetBSD as well.

> > If not, or if correct fix takes time, we can avoid this specific problem 
> > by allocating memory in ahcattach(). (Though this is not correct fix, 
> > only workaround)

I don't know why NetBSD has problems allocating SCB space on demand.  Is
malloc(M_NOWAIT) likely to fail if used some time after boot?  There
is still no protection for calling malloc from an interrupt context as
well.  This is a separate problem to that of making it safe for a
resource request to fail from an interrupt context.

>Sometime during the release cycle for 1.2, we'll have to make a decision 
>whether or not putting in the work-around you suggest is appropriate as 
>a stop-gap, depending on whether or not the underlying problem of SCSI 
>resource allocation has been addressed.

There is also the change that FreeBSD put in that reduces the effects
of the problem by only setting SCSI_NOSLEEP when absolutely necessary.
FreeBSD still has the "Oops not queued" error message in its SCSI
system, but I haven't gotten one report of it happening in FreeBSD
yet.  It may be beneficial to use the same approach as a stop-gap
measure.

>----save the ancient forests - http://www.bayarea.net/~thorpej/forest/----
>Jason R. Thorpe                                       thorpej@nas.nasa.gov
>NASA Ames Research Center                               Home: 408.866.1912
>NAS: M/S 258-6                                          Work: 415.604.0935
>Moffett Field, CA 94035                                Pager: 415.428.6939

--
Justin T. Gibbs
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