From: Timur Tabi <timur@freescale.com>
To: Michael Barkowski <michaelbarkowski@ruggedcom.com>
Cc: linuxppc-dev@ozlabs.org
Subject: Re: Is volatile always verboten for FSL QE structures?
Date: Fri, 02 Oct 2009 09:46:31 -0500 [thread overview]
Message-ID: <4AC61247.1030507@freescale.com> (raw)
In-Reply-To: <4AC60AD8.8030509@ruggedcom.com>
Michael Barkowski wrote:
> Just wondering - is there a case where using volatile for UCC parameter RAM for example will not work, or is the use of I/O accessors everywhere an attempt to be portable to other architectures?
'volatile' just doesn't really do what you think it should do. The PowerPC architecture is too complicated w.r.t. ordering of reads and writes. In other words, you can't trust it.
No one should be using 'volatile' to access I/O registers.
--
Timur Tabi
Linux kernel developer at Freescale
next prev parent reply other threads:[~2009-10-02 14:46 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2009-10-02 14:14 Is volatile always verboten for FSL QE structures? Michael Barkowski
2009-10-02 14:46 ` Timur Tabi [this message]
2009-10-02 16:41 ` Kumar Gala
2009-10-02 16:57 ` Michael Barkowski
2009-10-02 18:08 ` Guillaume Knispel
2009-10-03 9:55 ` Simon Richter
2009-10-03 11:20 ` Benjamin Herrenschmidt
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