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Re: DECStation: Support for PMAZ-AA TC SCSI card?

To: "Maciej W. Rozycki" <macro@ds2.pg.gda.pl>
Subject: Re: DECStation: Support for PMAZ-AA TC SCSI card?
From: Ralf Baechle <ralf@oss.sgi.com>
Date: Mon, 22 Jul 2002 15:44:05 +0200
Cc: "Houten K.H.C. van (Karel)" <vhouten@kpn.com>, linux-mips@oss.sgi.com
In-reply-to: <Pine.GSO.3.96.1020722132706.2373A-100000@delta.ds2.pg.gda.pl>; from macro@ds2.pg.gda.pl on Mon, Jul 22, 2002 at 02:21:13PM +0200
References: <200207191708.TAA04858@sparta.research.kpn.com> <Pine.GSO.3.96.1020722132706.2373A-100000@delta.ds2.pg.gda.pl>
Sender: owner-linux-mips@oss.sgi.com
User-agent: Mutt/1.2.5.1i
On Mon, Jul 22, 2002 at 02:21:13PM +0200, Maciej W. Rozycki wrote:

>  I hope so.  I'm begging Ralf for about half a year, sigh...  The subject
> was beaten to death at the list and the feedback looked positive to me
> (after a few doubts were resolved), but Ralf seems to be unhappy with the
> changes due to some ia64 interactions (I'm still not sure which ones,
> though).  Ralf, could you please elaborate? 
> 
>  Otherwise, your case convinces me I should not care about purity or
> cross-platform consistency of code in this area, anymore.  I've been
> observing problems with interrupts due to the lack of iomem access
> synchronization already, but unlike for your PMAZ-A problem, their result
> was more of annoyance than instability.  Since stability is a priority,
> although reluctantly, I will rework the changes to apply to the DECstation
> code only, to keep others happy.  The interface won't change, apart from
> resolving namespace clashes.

We had some discussion with the IA64 guys at SGI on how to handle this
kind of I/O ordering issues.  We never came to a final conclusion but
the proposal was the introduction of separate memory barriers macros for
I/O stuff.  Anyway, I think for the moment we should go with your proposal.

  Ralf


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