From: Daniel Jacobowitz <dan@debian.org>
To: "Richard B. Johnson" <root@chaos.analogic.com>
Cc: Linux kernel <linux-kernel@vger.kernel.org>
Subject: Re: atomic_t (24 bits???)
Date: Tue, 25 Feb 2003 14:17:11 -0500 [thread overview]
Message-ID: <20030225191711.GA25331@nevyn.them.org> (raw)
In-Reply-To: <Pine.LNX.3.95.1030225140554.20186A-100000@chaos>
On Tue, Feb 25, 2003 at 02:11:11PM -0500, Richard B. Johnson wrote:
>
> In ../linux/include/asm/atomic.h, for versions 2.4.18 and
> above as far as I've checked, there are repeated warnings
> "Note that the guaranteed useful range of an atomic_t is
> only 24 bits."
>
> I fail to see any reason why as atomic_t is typdefed to a
> volatile int which, on ix86 seems to be 32 bits.
>
> Does anybody know if this is just some old comments from a
> previous atomic_t type of, perhaps, char[3]?
There are other platforms where you can't reliably use the whole word.
Some ARM atomic_t implementations are like this, although I don't know
if the one in the kernel is.
--
Daniel Jacobowitz
MontaVista Software Debian GNU/Linux Developer
next prev parent reply other threads:[~2003-02-25 19:07 UTC|newest]
Thread overview: 6+ messages / expand[flat|nested] mbox.gz Atom feed top
2003-02-25 19:11 atomic_t (24 bits???) Richard B. Johnson
2003-02-25 19:14 ` Roman Zippel
2003-02-25 19:31 ` Richard B. Johnson
2003-02-25 19:17 ` Daniel Jacobowitz [this message]
2003-02-25 19:31 ` Richard B. Johnson
2003-02-25 21:57 ` Russell King
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