From: olof@lixom.net (Olof Johansson)
To: Jake Moilanen <moilanen@austin.ibm.com>
Cc: linuxppc-dev@ozlabs.org, paulus@samba.org
Subject: Re: [PATCH] DMA 4GB boundary protection
Date: Fri, 2 Mar 2007 16:27:48 -0600 [thread overview]
Message-ID: <20070302222748.GA1206@lixom.net> (raw)
In-Reply-To: <1172872183.5310.145.camel@goblue>
On Fri, Mar 02, 2007 at 03:49:43PM -0600, Jake Moilanen wrote:
> There are many adapters which can not handle DMAing acrosss any 4 GB
> boundary. For instance the latest Emulex adapters.
>
> This normally is not an issue as firmware gives us dma-windows under
> 4gigs. However, some of the new System-P boxes have dma-windows above
> 4gigs, and this present a problem.
>
> I propose fixing it in the IOMMU allocation instead of making each
> driver protect against it as it is more efficient, and won't require
> changing every driver which has not considered this issue.
Sorry, but you need to fix the drivers. They might be used on a system
without an IOMMU, or with direct mapping. It's particularily likely in
the case of DAC-capable devices, and that's the only case for which you
can cross a 4GB boundary in the first place.
-Olof
next prev parent reply other threads:[~2007-03-02 22:16 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-03-02 21:49 [PATCH] DMA 4GB boundary protection Jake Moilanen
2007-03-02 22:27 ` Olof Johansson [this message]
2007-03-03 8:27 ` Benjamin Herrenschmidt
2007-03-03 23:25 ` Olof Johansson
2007-03-04 5:17 ` Christoph Hellwig
2007-03-04 5:52 ` Olof Johansson
2007-03-03 23:29 ` Olof Johansson
2007-03-03 23:32 ` Segher Boessenkool
2007-03-03 23:57 ` Olof Johansson
2007-03-21 21:05 ` Jake Moilanen
2007-03-21 21:39 ` Olof Johansson
2007-03-22 17:53 ` Olof Johansson
2007-03-22 17:47 ` Jake Moilanen
2007-03-22 22:52 ` Segher Boessenkool
2007-03-27 20:10 ` Jake Moilanen
2007-03-27 20:55 ` Benjamin Herrenschmidt
2007-03-27 23:48 ` Paul Mackerras
2007-03-28 15:56 ` Olof Johansson
2007-03-28 18:17 ` Jake Moilanen
2007-03-28 23:23 ` Benjamin Herrenschmidt
2007-03-29 13:44 ` Jake Moilanen
2007-03-29 14:52 ` Olof Johansson
2007-03-29 21:54 ` Benjamin Herrenschmidt
2007-04-23 12:22 ` Paul Mackerras
2007-04-24 3:07 ` Olof Johansson
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