From owner-freebsd-current@FreeBSD.ORG  Thu May  6 09:08:27 2004
Return-Path: <owner-freebsd-current@FreeBSD.ORG>
Delivered-To: freebsd-current@freebsd.org
Received: from mx1.FreeBSD.org (mx1.freebsd.org [216.136.204.125])
	by hub.freebsd.org (Postfix) with ESMTP id ABEC216A4CF
	for <current@FreeBSD.org>; Thu,  6 May 2004 09:08:27 -0700 (PDT)
Received: from mailout1.pacific.net.au (mailout1.pacific.net.au [61.8.0.84])
	by mx1.FreeBSD.org (Postfix) with ESMTP id 06A1D43D54
	for <current@FreeBSD.org>; Thu,  6 May 2004 09:08:27 -0700 (PDT)
	(envelope-from bde@zeta.org.au)
Received: from mailproxy2.pacific.net.au (mailproxy2.pacific.net.au
	[61.8.0.87])i46G834u004826;	Fri, 7 May 2004 02:08:03 +1000
Received: from gamplex.bde.org (katana.zip.com.au [61.8.7.246])
	i46G80HW012618;	Fri, 7 May 2004 02:08:01 +1000
Date: Fri, 7 May 2004 02:07:59 +1000 (EST)
From: Bruce Evans <bde@zeta.org.au>
X-X-Sender: bde@gamplex.bde.org
To: Mark Santcroos <marks@ripe.net>
In-Reply-To: <20040506120541.GA1131@laptop.6bone.nl>
Message-ID: <20040507015534.D21163@gamplex.bde.org>
References: <20040505195425.GA2559@laptop.6bone.nl>
	<409948A7.1040100@DeepCore.dk><20040506120541.GA1131@laptop.6bone.nl>
MIME-Version: 1.0
Content-Type: TEXT/PLAIN; charset=US-ASCII
cc: current@FreeBSD.org
cc: S?ren Schmidt <sos@DeepCore.dk>
Subject: Re: ATA_FLUSHCACHE failing
X-BeenThere: freebsd-current@freebsd.org
X-Mailman-Version: 2.1.1
Precedence: list
List-Id: Discussions about the use of FreeBSD-current
	<freebsd-current.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>,
	<mailto:freebsd-current-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-current>
List-Post: <mailto:freebsd-current@freebsd.org>
List-Help: <mailto:freebsd-current-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-current>,
	<mailto:freebsd-current-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Thu, 06 May 2004 16:08:27 -0000

On Thu, 6 May 2004, Mark Santcroos wrote:

> On Thu, May 06, 2004 at 09:36:31PM +1000, Bruce Evans wrote:
> > Panic dumps cannot use either device interrupts or timeouts, not to
> > mention normal locks, since panics may occur in almost any context;
> > in particular they may occur with all interrupts masked and important
> > locks in a bad state.  Immediate mode must be used, but it doesn't
> > seem to be, and a comment says that it is only used for other things:
>
> My eye felt on the same code and comments!
>
> But if this is indeed the problem, why isn't everyone experiencing this
> issue?

The work in some contexts.  E.g., when the panic is in MPSAFE syscall
context.

> Stated differently, are there problems with using ATA_IMMEDIATE_MODE?

Don't know.  I thought that ata aleady used immediate mode for i/o
(write only), and seem to remember it breaking once before when the
immediate bit got lost.  Relatively recent use of queues and semaphores
complicated things.  See the wd driver in RELENG_[34] for how easy it
used to be do the i/o directly.

Bruce