Subject: Re: volatile variable
From: Robert Love <rml@tech9.net>
To: root@chaos.analogic.com
Cc: David Woodhouse <dwmw2@infradead.org>,
       Dinesh Gandhewar <dinesh_gandhewar@rediffmail.com>,
       mlist-linux-kernel@nntp-server.caltech.edu
In-Reply-To: <Pine.LNX.4.53.0308110944350.17240@chaos>
References: <20030801105706.30523.qmail@webmail28.rediffmail.com>
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	 <1060608783.19194.13.camel@passion.cambridge.redhat.com>
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Date: Mon, 11 Aug 2003 10:07:02 -0700
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On Mon, 2003-08-11 at 07:06, Richard B. Johnson wrote:

> The regparm(0) atttibute tells gcc that schedule() will get any/all
> of its parameters in registers. Since schedule() receives no parameters,
> that means that, as far as gcc is concerned, it cannot modify
> anything. That said, this may be a bug or it may have been added
> to work around some gcc bug. But, nevertheless, as the declaration
> stands, schedule() will never modify anything because somebody told
> gcc it won't.

No, regparm(0) means "zero parameters in registers", so everything is to
be found on the stack.

Also, the notion of functions as compiler barriers has nothing to do
with arguments. It has to do with global variables and pointers from
who-knows-where.

All functions are compile barriers, regardless of regparm() magic or the
number of parameters, with the exception of functions with the gcc
'pure' keyword.

Also, sleep_on() is deprecated and bad. Thanks for trolling today.

	Robert Love


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