Return-Path: <linux-kernel-owner+w=401wt.eu-S1755381AbYKKGMr@vger.kernel.org>
Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand
	id S1755381AbYKKGMr (ORCPT <rfc822;w@1wt.eu>);
	Tue, 11 Nov 2008 01:12:47 -0500
Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751859AbYKKGMj
	(ORCPT <rfc822;linux-kernel-outgoing>);
	Tue, 11 Nov 2008 01:12:39 -0500
Received: from mta23.gyao.ne.jp ([125.63.38.249]:51945 "EHLO mx.gate01.com"
	rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP
	id S1751111AbYKKGMi (ORCPT <rfc822;linux-kernel@vger.kernel.org>);
	Tue, 11 Nov 2008 01:12:38 -0500
Date: Tue, 11 Nov 2008 15:11:40 +0900
From: Paul Mundt <lethal@linux-sh.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: Hitoshi Mitake <h.mitake@gmail.com>, Hitoshi Mitake <mitake@clustcom.com>,
       Doug Thompson <norsk5@yahoo.com>, dougthompson@xmission.com,
       linux-kernel@vger.kernel.org, ktaka@clustcom.com,
       linux-arch@vger.kernel.org
Subject: Re: [PATCH 1/1] edac x38: new MC driver module
Message-ID: <20081111061140.GB32733@linux-sh.org>
Mail-Followup-To: Paul Mundt <lethal@linux-sh.org>,
	Andrew Morton <akpm@linux-foundation.org>,
	Hitoshi Mitake <h.mitake@gmail.com>,
	Hitoshi Mitake <mitake@clustcom.com>,
	Doug Thompson <norsk5@yahoo.com>, dougthompson@xmission.com,
	linux-kernel@vger.kernel.org, ktaka@clustcom.com,
	linux-arch@vger.kernel.org
References: <20081105222911.d76e7e1c.mitake@clustcom.com> <413709.12821.qm@web50106.mail.re2.yahoo.com> <20081106164641.ed369060.akpm@linux-foundation.org> <20081107152830.a42766f3.mitake@clustcom.com> <20081106223122.8a255211.akpm@linux-foundation.org> <20081107153824.0ec934e6.mitake@clustcom.com> <20081106231102.aab83cd4.akpm@linux-foundation.org> <a6b9f31a0811090710y17e956bawf20675d6678b145e@mail.gmail.com> <20081109112646.97c594b5.akpm@linux-foundation.org>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20081109112646.97c594b5.akpm@linux-foundation.org>
User-Agent: Mutt/1.5.13 (2006-08-11)
Sender: linux-kernel-owner@vger.kernel.org
List-ID: <linux-kernel.vger.kernel.org>
X-Mailing-List: linux-kernel@vger.kernel.org
Content-Length: 1584
Lines: 43

On Sun, Nov 09, 2008 at 11:26:46AM -0800, Andrew Morton wrote:
> (cc linux-arch)
> 
> > It seems that architectures that provide readq/writeq are
> > mips, parisc and x86 (and x86_64).
> > 
There are more than that, grep arch/*/include also.

In addition to mips, parisc, and x86, there is ia64, alpha, sh, and
sparc.

> #ifdef readq
> 
> Is a suitable way of determining whether the architecture implements
> readq and writeq.  It isn't pretty, but it will suffice.
> 
> A problem with it is that drivers will then do
> 
> #ifndef readq
> <provide a local implementation here>
> #endif
> 
> which rather sucks - we don't want lots of little private readq/writeq
> implementations all over the tree.
> 
> Perhaps it would be better to have a CONFIG_ARCH_HAS_READQ and to then
> disable these drivers on the architectures which don't provide
> readq/writeq support.
> 
However this is handled, we don't want a rehash of the read/writes{b,w,l} fiasco.

Allowing drivers to do their own local implementations of these things
has always been a complete disaster. A Kconfig option will at least take
care of having these craptastic ifdef lists for architectures in every
driver that rolls its own implementation.

Even a sub-optimal asm-generic version would be preferable, if the
semantics are well enough defined and consistently adhered to.
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@vger.kernel.org
More majordomo info at  http://vger.kernel.org/majordomo-info.html
Please read the FAQ at  http://www.tux.org/lkml/