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From: "Bryan O'Sullivan" <bos@serpentine.com>
To: Roland Dreier <rdreier@cisco.com>
Cc: Bill Waddington <william.waddington@beezmo.com>,
	linux-kernel@vger.kernel.org
Subject: Re: Flushing writes to PCI devices
Date: Thu, 21 Sep 2006 14:04:00 -0700	[thread overview]
Message-ID: <1158872640.1996.9.camel@chalcedony.pathscale.com> (raw)
In-Reply-To: <adavenhgcpw.fsf@cisco.com>

On Thu, 2006-09-21 at 13:56 -0700, Roland Dreier wrote:
>     Bryan> Yes.  If your device requires that writes to some locations
>     Bryan> in MMIO space be performed in a specific order, you must
>     Bryan> explicitly do this in your driver.  Intel CPUs will flush
>     Bryan> posted writes out of order, for example.
> 
> Really?  Just normal posted PCI writes without using MTRRs or
> write-combining or anything like that?

No, not normal writes, but if you're writing to an area where you've
enabled write combining, it will happen (but not IIRC on AMD x86_64
CPUs).  Sorry for the lack of clarity.

	<b


  reply	other threads:[~2006-09-21 21:04 UTC|newest]

Thread overview: 10+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <fa.gbsNbubc34pqWPOxWCntrwUyt68@ifi.uio.no>
2006-09-20 18:28 ` Flushing writes to PCI devices Alan Stern
2006-09-20 19:10   ` linux-os (Dick Johnson)
     [not found]   ` <fa.V4O8HKrhUddxYm5+ixVbyZzPybE@ifi.uio.no>
2006-09-20 19:41     ` Bill Waddington
2006-09-20 20:17       ` linux-os (Dick Johnson)
2006-09-21 18:14       ` Bryan O'Sullivan
2006-09-21 18:45         ` Alan Cox
2006-09-21 20:56         ` Roland Dreier
2006-09-21 21:04           ` Bryan O'Sullivan [this message]
2006-09-20 22:39   ` Alan Cox
2006-09-20 23:22 ` Robert Hancock

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