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
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20070601202601.GM7217@one.firstfloor.org \
--to=andi@firstfloor.org \
--cc=andrew.vasquez@qlogic.com \
--cc=hch@infradead.org \
--cc=linux-kernel@vger.kernel.org \
--cc=riel@redhat.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is an external index of several public inboxes,
see mirroring instructions on how to clone and mirror
all data and code used by this external index.