From owner-freebsd-mips@FreeBSD.ORG  Tue Oct  4 17:47:56 2011
Return-Path: <owner-freebsd-mips@FreeBSD.ORG>
Delivered-To: freebsd-mips@freebsd.org
Received: from mx1.freebsd.org (mx1.freebsd.org [IPv6:2001:4f8:fff6::34])
	by hub.freebsd.org (Postfix) with ESMTP id D8CA71065670;
	Tue,  4 Oct 2011 17:47:56 +0000 (UTC)
	(envelope-from c.jayachandran@gmail.com)
Received: from mail-wy0-f182.google.com (mail-wy0-f182.google.com
	[74.125.82.182])
	by mx1.freebsd.org (Postfix) with ESMTP id 18C958FC19;
	Tue,  4 Oct 2011 17:47:55 +0000 (UTC)
Received: by wyj26 with SMTP id 26so1088628wyj.13
	for <multiple recipients>; Tue, 04 Oct 2011 10:47:55 -0700 (PDT)
DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma;
	h=mime-version:sender:in-reply-to:references:date
	:x-google-sender-auth:message-id:subject:from:to:cc:content-type
	:content-transfer-encoding;
	bh=s94I4xWp3RdnYhIWZPboLE6AgTzzzlS+kMjZwA2LJqo=;
	b=ANQZfRPeilPBBicuQbiGMIgkc/m4g6xKpxG3PXTtDQ/V4jcY9lwFHbsfA5Aj2rbv+f
	nyY5EZsjNNfnH+PSOPd8uGxp38SBrxXBEQSl6s6cUFWzOpr4i2ATz/z4pggkUxN8Ep+X
	lMGHtWOV4GTG/ejBXMe1m/hWXjqLm0l8etqvU=
MIME-Version: 1.0
Received: by 10.216.14.201 with SMTP id d51mr1783461wed.56.1317750474859; Tue,
	04 Oct 2011 10:47:54 -0700 (PDT)
Sender: c.jayachandran@gmail.com
Received: by 10.216.29.78 with HTTP; Tue, 4 Oct 2011 10:47:54 -0700 (PDT)
In-Reply-To: <AC6674AB7BC78549BB231821ABF7A9AEB80CB1FE93@EMBX01-WF.jnpr.net>
References: <kor1ebmmdclae4u7bstwrc2c.1317741744919@email.android.com>
	<AC6674AB7BC78549BB231821ABF7A9AEB80CB1FE93@EMBX01-WF.jnpr.net>
Date: Tue, 4 Oct 2011 23:17:54 +0530
X-Google-Sender-Auth: bCVXIL3NSltuI3eXt7mp3cyeMFM
Message-ID: <CA+7sy7AncTdRDN88DaiPsBDc=PQ3N6UR9VAb7chOOp7XDXS=Sw@mail.gmail.com>
From: "Jayachandran C." <jchandra@freebsd.org>
To: Andrew Duane <aduane@juniper.net>
Content-Type: text/plain; charset=ISO-8859-1
Content-Transfer-Encoding: quoted-printable
Cc: Kostik Belousov <kostikbel@gmail.com>, Alexander Motin <mav@freebsd.org>,
	"freebsd-mips@freebsd.org" <freebsd-mips@freebsd.org>
Subject: Re: svn commit: r225892 - head/sys/mips/mips
X-BeenThere: freebsd-mips@freebsd.org
X-Mailman-Version: 2.1.5
Precedence: list
List-Id: Porting FreeBSD to MIPS <freebsd-mips.freebsd.org>
List-Unsubscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-mips>,
	<mailto:freebsd-mips-request@freebsd.org?subject=unsubscribe>
List-Archive: <http://lists.freebsd.org/pipermail/freebsd-mips>
List-Post: <mailto:freebsd-mips@freebsd.org>
List-Help: <mailto:freebsd-mips-request@freebsd.org?subject=help>
List-Subscribe: <http://lists.freebsd.org/mailman/listinfo/freebsd-mips>,
	<mailto:freebsd-mips-request@freebsd.org?subject=subscribe>
X-List-Received-Date: Tue, 04 Oct 2011 17:47:56 -0000

On Tue, Oct 4, 2011 at 9:34 PM, Andrew Duane <aduane@juniper.net> wrote:
> The MIPS manual volume 3 says there is a 3 cycle "typical" wait between a=
n MTC0 that messes with Status[IE] and an interrupted instruction. That haz=
ard doesn't seem to apply here, to any of the cases we have.
>
> I do have a question: in StartWaitSkip, the value of Status[IE] is being =
toggled, not cleared. Is that correct? Do we always guarantee that it will =
be set on entry here?

Interrupts have to be enabled in cpu_idle(), there is an assert in the
beginning of cpu_idle which checks this.

> I had also made a comment about the "PTR_ADDU k1, 16 =A0 =A0# skip over w=
ait" in MipsKernIntr; I think it would be safer (and clearer) to do "PTR_LA=
 =A0 =A0 =A0 =A0k1, EndWaitSkip" instead.

Loading an immediate address takes more instructions (esp in 64 bit)
adding 16 is just one instruction.  I should really add an KASSERT
somewhere to make sure that EndWaitSkip - StartWaitSkip is 16...

JC.