Re: [PATCH] x86: Remove readq()/writeq() on 32-bit

From: "H. Peter Anvin" <hpa@zytor.com>
To: Jeff Garzik <jeff@garzik.org>
Cc: Hitoshi Mitake <h.mitake@gmail.com>,
	Roland Dreier <rdreier@cisco.com>, Ingo Molnar <mingo@elte.hu>,
	David Miller <davem@davemloft.net>,
	Linus Torvalds <torvalds@linux-foundation.org>,
	tglx@linutronix.de, rpjday@crashcourse.ca,
	linux-kernel@vger.kernel.org
Subject: Re: [PATCH] x86: Remove readq()/writeq() on 32-bit
Date: Wed, 13 May 2009 14:54:01 -0700	[thread overview]
Message-ID: <4A0B4179.1000504@zytor.com> (raw)
In-Reply-To: <4A0B3BF3.1050804@garzik.org>

Jeff Garzik wrote:
>>>
>> I have personally dealt with at least one device who'd want to opt out
>> of a standard readq/writeq (it's not in-tree because it never shipped,
>> unfortunately.)  Doing the opt-in headers seems like a reasonable thing
>> to do to me, but perhaps I'm just being overly paranoid.
> 
> Isn't that a variant of "punish all sane hardware, because bizarre 
> unshipped hardware exists"?
> 
> IMO the best fix is to document existing readq assumptions, and 
> standardize that definition on other platforms.
> 
> The burden of special casing for bizarre hardware should not fall on 
> /sane/ drivers and hardware, who should be the ones opting _out_ of the 
> standard regime.
> 

It sort of is, but it's also a case of "explicitly documenting your
assumptions".  You have do admit that having to #include a single extra
header file is hardly a hardship.

	-hpa