From: Andi Kleen <andi@firstfloor.org>
To: Rik van Riel <riel@redhat.com>
Cc: Andi Kleen <andi@firstfloor.org>,
Andrew Vasquez <andrew.vasquez@qlogic.com>,
Christoph Hellwig <hch@infradead.org>,
linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] quiet down swiotlb warnings
Date: Fri, 1 Jun 2007 22:26:01 +0200 [thread overview]
Message-ID: <20070601202601.GM7217@one.firstfloor.org> (raw)
In-Reply-To: <46607F96.7060200@redhat.com>
On Fri, Jun 01, 2007 at 04:20:38PM -0400, Rik van Riel wrote:
> Andi Kleen wrote:
> >On Fri, Jun 01, 2007 at 01:00:49PM -0700, Andrew Vasquez wrote:
> >>yes, the card can support 64bit DMA transfers. but in this case the
> >>'required' DMA mask returned from dma_get_required_mask() states that a
> >>32bit mask would suffice.
> >
> >That's a bug in the kernel then that needs to be fixed. Find out
> >why it does that and change it. Don't fix the symptoms, fix the root cause.
>
> The system in question only has 2GB of memory.
>
> Why would it need to do 64 bit DMA?
It doesn't. But it definitely doesn't need swiotlb either.
Normally swiotlb doesn't even try to bounce when dma mask is <= end_pfn
so something must be very wrong in your kernel. It definitely isn't
a mainline kernel. If this happens in Xen then Xen just needs fixing --
it should not try to bounce when the normal kernel wouldn't.
-Andi
next prev parent reply other threads:[~2007-06-01 20:26 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2007-06-01 17:30 [PATCH] quiet down swiotlb warnings Rik van Riel
2007-06-01 19:01 ` Andi Kleen
2007-06-01 18:12 ` Christoph Hellwig
2007-06-01 18:18 ` Rik van Riel
2007-06-01 19:37 ` Andi Kleen
2007-06-01 19:38 ` Rik van Riel
2007-06-01 19:47 ` Andi Kleen
2007-06-01 20:00 ` Andrew Vasquez
2007-06-01 20:14 ` Andi Kleen
2007-06-01 20:20 ` Rik van Riel
2007-06-01 20:26 ` Andi Kleen [this message]
2007-06-02 15:21 ` Muli Ben-Yehuda
2007-06-02 16:47 ` Andi Kleen
2007-06-01 19:57 ` Christoph Hellwig
2007-06-01 18:16 ` Andrew Vasquez
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